Compressor Motor - Part 1 - Soft Starter
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- Опубліковано 5 вер 2024
- We've run our Max-Air 90 off grid power, but it's 7.5 hp Baldor L1509T motor struggles on our 10kw generator. So we try out a Stellar SR35 series, 52A, 110-240 VAC at 1-phase soft starter.
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"Trickin Pickin" preformed by Doug Waterman
We've run our Max-Air 90 off grid power, but it's 7.5 hp Baldor L1509T motor struggles on our 10kw generator. So we try out a Stellar SR35 series, 52A, 110-240 VAC at 1-phase soft starter.
If your going to use a VFD why not flip to a 3 phase motor? The startup would be easier as there is internal stuff your fighting in the motor if single phase Ie: the startup cap/circuit.
Keep fighting the good fight! This work isnt as glamerous as building the boat, but its just as impressive to watch you blaze this trail!
Why would you go to a 220v compressor if you're not going to be doing commercial diving anyway? There's many 110v, gas and diesel options for tank compressors out there. Remember the golden rule, Simple, efficient, effective, dependable. You don't want to be troubleshooting while you're out.
@@ligarsystm good idea. maybe a slightly higher hp motor at the same time to reduce the ir losses in the motor too. some compressors have the ability to relieve the chamber pressure during startup, similar to a diesel engine jake braking. maybe there is a bolt in the cylinder head that can have a relief valve installed that you can throttle once the compressor is spinning at full speed.
It only becomes 2 phase if you have a neutral+ 2 phases. Is the unloader valve working? Usually compressors are open to atmosphere for start up to take the load off the motor and allow the flywheel to get up to speed then the valve shuts.
Compression release valve. If you install a valve at the output of the compressor head. with the compressor venting it will spin easily. Open valve, turrn on compresser. Once it is turning fast, then close the valve.
Reading through the comments, you seem to think there is no load on the compressor at start, but the motor not spinning and the belt flexing says otherwise. If it was just internal friction, that motor would spin it easily. An unloaded compressor should spin by hand.
Exactly, there needs to be modified unloading for a slower startup. Otherwise it's always trying to compress air even during startup. I would try this before spending on anything else.
I totally agree with this. You need an unloader valve to allow the motor to reach full speed before compressing air. A manual dump valve would even do to keep it simple
Multi stage compressor, It would need several unloader valves between the cylinders.
As it is now the final stage is unloaded.
Agreed. I have already looked at parts online and, if you really wanted to, you can automate the start up by using a delay timer and a normally open solenoid valve to drain air. Have the timer set for turning on after the motor is at full speed, and when the timer is done it will send power to the solenoid and make it stop draining air.
@@devinholland2189 Shouldn't unloading the first stage cylinder be enough (assuming it's large enough to buffer the start)?
In the HVAC industry they use adjustable pulleys. If you can get away with one (might have downsides that stops it in this application) you can tune the speed vs torque.
Dough, you can confirm all of this information, including the locked rotor current on the manufacturer's plate on the motor. Cheapest and easiest solution is probably just buy a smaller scuba air compressor that has a motor on it with under a locked rotor current of less than 42A at 240 VAC, then sell this beast off. Keep the soft start for what ever solution you end up using.
Ok, I took a look at my actual motors class textbook and ran a locked rotor current calculation for the type of motor commonly used for positive displacement pumps, which is what an air compressor is. Assuming a NEMA type "C" motor, the locked rotor current comes to 80.96A, at 240 nominal, that's 17.28 kW. That generator is never going to be able to start that motor from a locked rotor state. It just physically doesn't have the power. Grid power can supply a lot more amperage, even through a breaker, for brief periods above what the circuit is rated for since you have Megawatts of power available off the grid.
You could try using a clutch pack, which still might not work and would be a hard to replace wear item. Changing the pulleys might be a solution. Plan on using a stronger belt that is wider or an additional belt so you don't have belt slipping or premature breakage. Another option would be to have a hydraulic starting assist motor that decouples as the electric motor spins up since it it just the locked rotor state that is causing the problem, but that is added complexity and expense. Ideally, you need more current, just for the startup of the pump. It is a pity that you can't boost the starting current from the charged batteries you have because they can discharge current very fast and would get you over the locked rotor with only a small total Watt hour draw. With the batteries added, you have the total energy onboard Seeker to get that motor started. It just needs to be in the right form and routed there.
An option would be a variable frequency drive that supported simultaneous AC and DC power input and was rated for the additional 7kW for start up you are short, just for the soft start phase of the startup, then the generator would be supplying it exclusively. Such a drive is going to cost a couple to several thousand dollars US, so I don't think it is economical to use. With more information on the details of your entire power setup and how it is wired, I might be able to come up with a more viable solution, but that would involve having physical access to the wiring or an accurate wiring diagram and the exact models and configuration you have for Seeker's power systems. This is the shortcoming of the video only documentation you have since I would need to watch all the raw video to know how everything is wired and configured, going through who knows how many days of video, when a wiring diagram could just be linked to as a document.
Yes, I could figure this out in a day or less if I was onsite, but I am a bit far away to do that and with my father just returning home from the hospital, I can't leave home right now. I would suggest you see if there are any industrially trained electrical engineers or electricians in the fans that can come by and do this work.
Low voltage 3-phase (240) is available in either a "Y" configuration or with a wild leg or stinger 'Delta configuration}, the two are not interchangeable. If you're checking existing power the "Y" will be 120v to ground on all three legs. The Delta will test 120 to ground/120 to ground/ 240 to ground. Both systems check 240v testing leg to leg.
Make sure your equipment and supply are compatible, mistakes can be costly.
Should have paid more attention in electrical 101 class ⚡
Is there any advantage to this what is to me a weird system as here everything is 3phase Y 400v 50hz either available as such or split into 3x 230v to neutral?
As i understand it, yours saves a slight amount of copper in inductors due to the higher frequency, but here the wires only have to be half as thick in the first place, due to twice the voltage and safety is the same if you got an RCD.
@@hernerweisenberg7052 I can't answer. I'm merely a carpenter who had to learn enough to install and service my equipment. I'm not an electrician or an engineer.
@@tode5675 "merely"
Don't sell yourself to cheap man, carpentry is a science/art of its own :D
@@tode5675 Those mixed system just strike me as weird and antiquated. Imagine how much money you could make if you switch to the 230/400v system and could rip out and sell half of all electro-copper installed in the US. Little hard to do ofc since you would also have to replace every electric and electronic device in the country xD
I always wondered why single-phase 240 wasn’t considered “2-phase.” I did a little reading and, if memory serves, it’s because it really is one single phase on the transmission lines, but because of where they tap the secondary transformer windings, you get two legs that are 180 degrees out of phase. It’s sometimes called “split-phase.” 3-phase power is actually transmitted as three separate phases. Apparently there used to be true 2-phase power in use in certain parts of the United States. Also, most 3-phase now days is balanced (all three legs 120 degrees out of phase), high/wild/bastard leg isn’t used much anymore.
Hard start capacitors used on refrigeration compressors, usually remedy starting issues on loaded single phase motors.
Was thinking same thing. They are used on residential AC units and commercial three phase AC compressors.
It likely already has some inside the motor case, but upgrading them would help and would also correct the power factor, effectively lowering the needed current for starting.
Right on, run or start caps wired in with the compressor load.
@@ThAtGuY-u9d The genset unlike mains has a much lower power ratio this means there's just not enough power at any time to properly start the motor, there needs to be a controlled unloading on the first stage so the motor has the least amount of resistance during startup. once it reaches a steady state the unloader can be released. There's no amount of capacitance you can use to solve this issue, this only works on certain situations and its still seen as a brute force "solution". You can add as many capacitance as you want it won't work when the genset is limited to 1/10th of you typical current input. I suggest to fully unload the motor until it reaches the operating speed, even then once the compressor is loaded there may not be enough power available to fully start the compression cycle on this particular unit, with this particular setup. Basically the shoe is too small for the foot.
Quit blaming "things you have no control over" for things you clearly had control over. Letting go of things only helps when you really are helpless.
You are becoming everything you taught us not to be.
Interesting philosophy. Not for me, but I hope it brings you some happiness.
A few thoughts. The engine on the genny isn't bogging at all. I'm pretty sure you could pull all the power you want out of a generator until the current gets so high windings can't handle it or the engine stalls.
Run the voltage drop #s onnline and see what you come up with. If conductors are marginal the voltage drop could be killing everything. If the voltage drops too much the coil on your contactor in the control panel is dropping out which disconnects the motor momentarily also not helping the situation.
Try to manually hold in the contacts on the motor starter so the motor can actually get continuous power.
Another thing I've done is put the motor on a hinge with a lever so you can engage the belts slowly like on a lawn mower bascally a elcheapo clutch.
As mentioned by others add a capacitor bank with a voltage potential relay. When the voltage drops on startup it engages the extra start capacitors. Then as the voltage comes back up the relay opens removing them from the circuit.
Lastly figure out how to make the compressor unload and run continuous after its running. That motor isn't going to love frequent start stop cycles at those high amperages.
I sure like that plant stand at the end where you showcased projects you're working on. Very, very pretty!
Nice walk. I would try bigger start capacitor and some running capacitors as well.
I guess you have the bleed valves open Doug, it is the last stage in the comp which does all the end work. My 300 bar single phase I leave the wet stack open then close it to start making air.
However as you know your 10k genny is not like grid power.
My comp was micro bore but I swapped it to 1/4" bore fittings.
More power Igor
Contactor is kicking out, if you hold the contactor in manually (with a screwdriver or etc) it should pull through. What voltage regulator is on the generator? Under freq roll off is maybe set too high, the voltage drop seems excessive for 58hz, even if its shunt excited. Other options would be to power the contactor from a seperate source, such as a DC coil on the contactor, increase generator rpm to give it more room for droop, or some thing to increase excitation, a PMG or powering thr AVR off a seperate powrr source. Not sure what the setup is on your particular gen... Lots of different ways to solve it though.
Source: 15 years starting big pumpjack motors on generator
i was looking forward to this posting as i have a soft start mech to fit to a fairground ride. thanks Doug....
A single prop, no thrusters... how do you plan on staying on station or docking when no tug is available? Seems like you never had a boat before....
Trying to start that motor looks like me finding out my workshop wont run on our supply and no matter what i do now its going to cost. If only VFD and start capacitors could fix voltage drop/amp increase/line loss the calculations hurt sometimes haha
Also generators are meant to run at about 80% load so running a 10kw motor on a 10kw generator wont work
Lots of options to fix your current problem so sure you will get there :)
A REALLY old memory from 8th grade shop class says part of the reason for the different power legs being out of phase helped motors keep turning once they start. two phase is great, 3 phase even better. I also seem to remember an experiment where it wasn't out of phase and the motor ran like crap.
Are both legs of your 220 actually out of phase with each other? It runs fine on grid, but not on generator. Would think it's more of a power source problem, not a compressor motor problem.
They are. You can see it on the volt meter. The way the generator is wound, they have to be.
Three phase is a compromise between power transfer efficiency and the cost of the wiring to transmit it. It is also able to start induction motors without additional windings (shaded pole) or large capacitors while also being able to reverse a motor by just swapping two of the phases.
I noticed when you started the generator, the display said 238V 50HZ. If the motor for your compressor is rated for 60HZ, it will have 20% less HP when running on 50HZ power. There could be a setting on the generator to make 60HZ power, or like you already mentioned, a smaller pulley on the motor may compensate for the reduction in power.
If you change out the drive pulley for a smaller one, to reduce the starting load, as suggested, you can probably increase the run frequency of the soft starter to compensate for the speed reduction. Most inverters/soft starters can do this but I'm not familiar with that brand/model.
Agree with others making sure there is an unloader valve at the compressor head. Also beware that if you spin the compressor slower the flywheel will have less inertia and will provide less cooling via the fan blades, may cause problems but impossible to know until you test it.
You are right about the smaller pulley. The pre filter drain kept open on startup will also help a tiny bit. Did I see in one of the earlier videos that you have a bulk air bank installed ? If so, then the smaller pulley won’t make much difference to you as you will be running constantly for intervals to charge the bank. Also the motor will cool slightly better and last a bit longer running with less load. Worst case scenario, replace it with a small 2 stroke diesel or petrol engine.
Or you could install a run start capacitor. That would act as a hard start and give the extra jolt needed to start that compressor
OFF LOAD! the compressor.
Fit a solenoid to the discharge side open to atmosphere while starting.
Good luck dude.
Kev.F west of Ireland 🇮🇪
Speaking as an electrician, most don't understand 2 phase including myself. I understand that there is an actual 2 phase and still being used back at Niagara Falls where Tesla set up the 1st A/C power grid.
3 phase all three wires are out of phase 120° instead of 220v is just 180° out...I know it's weird
weird is a word for a concept with which we are not familiar...each cycle of AC (alternating current) has 360 degrees...divide that in half ="2 phase" you have 180 degrees...divide it in thirds you have 3 phase or 120 degrees. The windings on the motors are engineered to use the various phase setups to help spin the motor.
Does the motor run with the belt off?
For your edification: 2 phase 220 the phases are 180 degrees apart. In three phase 220(208) the phases are 120 degrees apart. In the two phase situation if you do not have a ground reference there is essentially no difference between considering one of the phases ground and the other 220V relative to that. From an outside view relative to earth ground they are both 120V. but ground is a relative term and somewhat arbitrary like the velocity of an object. My car is travelling 60mph (100kmh) relative to the ground but the earth is hurtling through space in an elliptic orbit and so is the car where in that case it is actually travelling thousands of miles per hour. Ground in ac circuits is like choosing the earth as a zero velocity point, arbitrary.
As for starting the compressor - the problem is similar to starting my lathe. At first I bought a 5HP Variable Frequency Drive to power the 5HP motor and it would go overcurrent every time I tried to start the lathe. It turns out that you need a minimum of 10HP worth of VFD to start a 5HP lathe and the same goes for a compressor. You are essentially trying to start the compressor motor under near full load conditions. As per Jaws - you might need a bigger boat.
Many buildings in the USA are run by pulling 2 legs off of 3 phase power. Its especially common in apartment buildings and large offices.
I like the "run the compressor slower" idea. I noticed when you looked at the generator output in the video that the voltage was LOW and the frequency was also LOW. This indicates the generator is at its limit of power capacity. For a given compression ratio on the compressor the amount of torque needed will be the same essentially regardless of RPM. (Depending on how the valves work on the compressor, the output pressure may also be a factor ) If you can produce that torque at a lower RPM then you have a lower power need. The belt idea is a winner if you ask me simple to work on simple to fix.
Awesome repair! Even if you can launch it tomorrow I would stay there and get everything ready hundred percent and then launch, ie test the anchor by dropping it in the lot etc.
No way. I have not done much of any sailing, but I’ve seen plenty of boats tied to the dock because of Skipper could find one more thing that needs to be fixed. And they ended up never leaving the dock.
My two pennies worth here Doug. At the company I worked at we used VFDs for all of our belt conveyors and any other equipment that might have to start under load or that required motors with a high starting torque requirement. I'm unfamiliar with the particular soft start unit you have as I don't recall ever using them. Most of the equipment was three phase so that may make a significant difference. Hope you have a great week and have success.
Anyone know of any commonly found vfds that take low input voltage such as 48v? ( Can always add a transformer to step the 3p up to motor demand)
my weekly amusement. Thanks SV Seeker
Howdy! , I think soft starters are not for mechanically loaded applications, they are for flywheel clutched machinery , must free-wheel for soft start. They should have designed a centrifugal sling shot clutch output on these larger electric motors to be able to spin up ./ Compressor manual start mod: each cylinder output to manifold , manifold to shunt valve - to vent in the pulled position like truck brakes - pushed in for normal passage , shunt valve to one way check valve , check valve to storage tanks. Allows the easier spin up of moving mass to speed up without back pressure on the pistons , start and push the valve to normalize. Note: Some compressors have extra output on each cylinder head top for auto switch to be plumbed to do exactly this and maybe easier to plumb in that way . An inch smaller driver pulley may solve a lot but at the same time watch the temp/current in the wires to drive motor, may indicate motor too hungry. "Perhaps a DC motor might be an option for low speed high torque". Problem solve is what I did today! Enjoy your creations!
Maybe the voltage drop over the wiring is too great? Try running it directly off the generator (or whatever you need to do to try out higher gauge wiring between the two for a test). Alternatively, can the motor be wired for 3 phase or something else (that may give you more options)
Smaller pulley for sure would help. Another thought: doesn't the compressor have an unloader for starting up? would keep the output of the cylinders open until it gets up to the operating rpm, if it doesn't and you can add something like that in place it will make it a ton of difference on startup, say a 10 sec delay, once the motor is up to speed it will most likely keep up and not stall. I don't think a VFD will work without the unloader (the soft start is more meant to save the belts than to help with the load at startup, the compressor should spin "freely" during the soft start, this is different than say an industrial fan where the load is increasing with the fan speed, here you have the same or more torque required at low rpm).
Three phase power has three voltages with each starting at a different time. These start or zero volt points occur every 120 degrees of the sine wave of the AC voltage. This gives voltages between any two phases as not simply the sum of the voltage of each leg but a total based on where each sine wave is at a specific point in time. For example that's how 208V becomes a voltage only in 3 phase when each leg has 120V and in single phase would be 240V. That's a starter for 3 phase without getting the square root of 3 over 2, a very popular dance for electricians.
Single phase voltage legs have the same start point, they're in phase with one another, with one going up and the other down. In other words there's only a single phase to the voltage.
All the compressors i have worked with had a mechanical are manual unload valve. Some industrial compressors had a electrical unload for startup.
This one does not, as there are no tanks attached.
120/240 is called single phase or split phase in the US because they take a single phase from the power companies 3 phase lines and the transformer on the pole splits it into 2 new "phases". So a single phase of high voltage comes into the transformer and you get 2 phases 180 degrees opposed out with neutral being the center tap of the two output phases. 120v between center (neutral) and either phase and 240 between the two phases.
What this guy said is right.
Hey doug not sure if this was suggested yet but I had this same problem using a generator on my job sights to power a compressor and ended up using a Centrifugal clutch on the compressor motor. They are available in many different pulley diameters, keep the speed of filling your tanks in ten minutes but gives the motor enough time to get going first. Good luck
Regarding the dive compressor. You can test with a valve that releases the compression, until the engine has come up in revs.
I have a simple idea maybe stupid to some but here goes you could use a big lawn mower electric activated pto clutch, all you do is get one that is the right shaft diameter and put a hold down on the PTO then start the motor and once it is at power use 12 volts dc to turn on the pto clutch using a smaller pulley that comes with the PTO Clutch.
Doug - at 1:43 the meter on the VMAC in the video shows 50.0 Hz. 999/1000 electrical things in the US today use 60.0 Hz power. Is the VMAC putting out 50 or 60 Hz???
Can you find a way to unload the compressor? Like adding a tee on the output with an open valve. Once the motor is up to speed close the valve slowly.
Scuba compressors are not loaded until their is a tank attached.
I use a timer activated solenoid valve in a compressor with a weak motor
@@SVSeeker Well there must be a lot of internal resistance to rotating in your unit then !
Surely the motor can rotate an unloaded compressor.
Does not work exactly like that Doug...scuba compressors keep the filter always pressurized so the ingoing air has more density and always flow slowly trough the filter. Compressor stopped, cylinder taken off ...your filter remains pressurized unless you activate manually (or auto) the purge valve at the base of the filter. There is a check valve that opens only at 150bar at the exit of the filter. Automatic purge systems do activate the purge valves during start for a few seconds....this reduces the charge on the final stage piston during start up. Also other middle stage oil separator and low pressure cylinders are purged.
If your compressor has no automatic purge, do it manually...open all purges and then start the compressor....once running, close them...
Personally I would give this a try before changing pulley ratio
a small change in size of the motor pulley will make more of a difference than the same size in inches change of the compressor pulley- if that makes sense? so removing an inch on the motor pulley is like adding 3 or 4 inches to the big one, so dont make a huge change, (Plus you'll run out of adjustment slot and have to buy a smaller belt) also making the belt wrap around a smaller driver pulley can increase belt heat under load - Maybe go with a ONE INCH smaller driver and see if you can sneak up on it to where it'll run better?
Right. Just the motor pully. The pump pulley would be very pricy to replace.
Doug, is it an option to get a clutch added in compressor's drive pulleys ? A centrifugal clutch that allows it to spin up to an rpm below it's engagement speed would get compressor motor running without full load of compressor, then when you raised rpms to operating speed for generating pressure for tanks ? If not centrifugal, an electric or even a manual clutch or manually operated tensioner might perform similarly.... Last idea, I promise... can you vent the compressor tank's temporarily to allow compressor spin up, THEN throttle a valve closed to generate pressure for tanks to be filled from ? Might be helpful to see a clamp on meter of power lines to see amperage being drawn at different operating phases.
My California air compressor has a presure release valve that allows the motor to start up and get up to speed before it starts to fill the tank. The hiss makes me jump every time. But it allows a twin pump to run on a 1.5hp motor.. It's just a thought.
I got one of those too. The difference is that it has a storage tanks.
Guess that pump doesn't have an unloader? You could put ball valves between the pump stages and shut them once the motor switches to it's primary windings.
Try blead any air pressure off the unit before starting.
Without scuba tanks attached there is no pressure.
I always watch to the end to hear the resonator guitar!
A VFD might work, as it can do a better job limiting the current, it can also ramp up over a longer time period. It also does a better job limiting current. A Soft Start and VFD are very similar but a VFD can have zero inrush where a soft start can not. What you see in the video is the motor is drawing more current then the generator can give, which causes a voltage drop, which causes more current.
Without more motor specific knowledge it is hard, but I think I saw a 7.5 HP motor (But according to some generator sizing software)
Direct On Line/Across the line - 18.1kVA starting peak. 9kVA running.
VFD 8.5kVA starting 7.7 kVA running.
They don't have Soft Start listed, but I would assume it would be in between the two. You can also get single to 3phase VFD's which could also help, but you would have to change the motor out.
to use a vfd you need a 3 phase motor. i once had a 10kw generator and a 3 phace 7.5hp lathe which didn't like to start. a vfd worked wonders. i don't know how it would act being fed by single phase though. i know you need to oversize the vfd.
@@xandriasmall6668 I use a VFD to convert from 220 to 3phase for my mill. Works like a charm. It theoretically sends back some bad ju-ju to the line, so I’m not sure if the smaller system of a generator and panel would be affected.
Need a smart electric person to chime in on that one.
I think compression relief valve would work. I have to do that on my shop comp in the winter open valve on head let it get spinning then close works good or else it will trip the breaker
Put a timed relief valve on compression line to close after motor is running at full speed, and increase you HZ to over 60, yes motors are picky.
start caps!!! if you wire a hard start kit with the soft starter it will store enough to not create voltage drop , we do this in the elevator industry , transformer , input to drive (that contains start caps ) usually 6-8 caps , then to main contactor or in hydraulics they run a soft start , siemans makes a pretty good setup . but the voltage drop is going to kill you upon start up .. (generate a cap bank to ease the start up load)
That’s it. No more mister nice-guy…
Remount it over the prop shaft and drive it with a hefty chain and overdrive sprocket setup. 😂
you might try unloading the compressor, IE vent the cylinder compression via decompression valves starting the unit and then closing them to build pressure, also you should be able to adjust the settings on the drive to accomidate the load and output
I would unload that compressor and start it then bring the load back onto the pump. I had to do that on a beefy air compressor I built at home. It would pop a breaker easily. I did that and it worked. Might could use a 12v electric clutch on the motor....
I think the term " three phase" is held for industrial use because all residential cannot get three phase from the grid.
What about adding a hand crank to help it out
Caveman engineering
It's single phase because literally there is only one phase of AC at 240. They get two legs of 120 by putting a center tap in the secondary transformer coil. It's still only one phase. There actually is a kind of setup called "two phase" that is not the same as this.
Ah. ...but are they in sync? So they are in different phases of the cycle. Yes! 2-phase. Don't worry, I'm not trying to change your world. I'm just going to mess with you because you make it such fun. : )
Capacitors could help, an engage mechanism would work(like a clutch, or belt idler). sounds like the phases are not aligned - Use The Auto TRANSFORMER coming in to the soft start and/or compressor. or rewire motor to work.
Doug I was just thinking about the boat I had pulling up into a marina and being told the water was hot. Never heard of that before. So I asked what’s that mean they explained other boats have electrical issues which makes the water electrified, that combined to salt water folks propellers would dissolve over night. You wake up finding out your prop is gone. The solution was zinc anoids but I’m not sure if you need zinc anoids on your ship or not??
In a typical single structure US residential single phase electrical power system the voltages are 120/240. In bigger structures fed with 3 phase power the voltages are 120/208. Different systems.
it allows the comp to free wheel till a set rpm then makes air
Those inverters will get back fed from the generator or vise versa, just a matter of time. Install an interlock
It might be a crazy idea, but maybe you can run the compressor off the hydraulic system? Perhaps with a direct drive hydraulic motor.
In other countrys where the regular house voltage is 220 AC like here in the US is 110 AC the current comes just like in 110 1 face (R, S or T) and a neutral cable (I say cable because the line is of several strands not a single like wires in the US. So the potential difference between the two in 220. Your problem may lie just there.
Hi Doug. Soft starters clamp the current at a fixed value, say 400%. This is OK sometimes and sometimes not, depends on your application. I think you’re suffering as the 400% is too little to get your compressor rolling plus your generator voltage is collapsing under load. Maybe have a loom first rapt starting the compressor unloaded. This is very common on large machines to reduce inrush from tripping supply breakers.
Happy to look in detail (WhatsApp call?) if you’d like some help figuring this out
It sure seems and looks like there is quite a bit of load on the compressor as start up. Not quite sure what is going on but it should turn easier at start up than that. Did you think about putting in a dump valve on the compressor outlet, to vent it during startup then close it after the system gets up to speed. That is if you have room for such a valve. Did you ever take the belt off and see how hard the compressor turns under no load? This seems strange to me that it turns so hard. You can see the belts are under quite a bit of load when it is trying to start. Let us know what you find out about this one please
It's called single phase because that's what it is. You have two lines, 110v, that are 180 degrees out of phase with each other...it's the same phase, only with one line's potential a total opposite of the other, thus doubling the 110V. Three phase is called that because they are not opposites of one another, but are actually 120 degrees OUT OF PHSE with each other because neither is a derivatative of the other.
A compressor unloader to let the air out of the head or the lines when it is starting up
You have probably already done this but, make sure the unloader is taking pressure off the pistons to facilitate easier starting. It will function automatically typically.
Totally agree on the stupid naming of our power. I say 2 phase 120V, and if you really want 1ph 240V but only if you don't have the neutral.
To eliminate drawdown from length of power source as well as maybe changing the capacitor / starter cap on the motor to start but I will try a direct source from generator to compressor to just see what happens
patience can only go for so long until it start to eat at you
It certainly could. But you'd have to allow it to eat on you.
Looking at the Baldor product specification page they list starting current at 205 amps ( seems steep but thats what the spec says), if that is true then you are just not getting enough amps to accelerate the motor to operating rpm. Will the motor accelerate if you uncouple the drive belt? If so maybe you could just use a belt engagement via a movable idler pulley
:Note a soft start can reduce starting current by up to 60% typically and even assuming that based on the Baldor specs you would need 82 amps to get the motor to spin up, double what you have on hand from the generator. (In theory at least. I would still take the belt off and see if you can spin it unloaded and measure the inrush):
That is the inrush current for the motor. The most the locked rotor state, which is what is keeping this from turning over, is likely lower, probably between 60 and 80 amps, depending on the motor that is being used. Did you find the NEMA designation letter for the motor in those specs? It would answer what the amperage we are trying to reach is.
@@KnightsWithoutATable
CAT.NO. JML1509T
SPEC. 37R88X77
HP 7.5
VOLTS 230
AMP 37
RPM 3450
FRAME 213JM HZ 60 PH 1
SER.F. 1.15 CODE G DES L CLASS F
NEMA-NOM-EFF 81 PF 82
RATING 40C AMB-CONT
CC USABLE AT 208V
DE 6309 ODE 6206
ENCL OPEN SN
Performance at 230 V, 60 Hz, 7.5 hp
Typical performance; not guaranteed values.
General Characteristics
Full Load Torque 0 LB-FT
No-Load Current 0 A
Line-Line Res. @ 25° C 0.23 Ohms A Ph / 0.799 Ohms B Ph
Temp. Rise @ Rated Load 58° C
Temp. Rise @ S.F. Load 73° C
Start Configuration DOL
Break-Down Torque 31 LB-FT
Pull-Up Torque 17 LB-FT
Locked-Rotor Torque 18 LB-FT
Starting Current 205 A
Load Characteristics
Rated Load 0% 25% 50% 75% 100% 125% 150% S.F.
Power Factor 19.0 46.0 65.0 76.0 82.0 85.0 87.0 84.0
Efficiency 0.0 61.3 73.9 78.2 79.5 79.3 78.1 79.4
Speed (RPM) 3,594 3,574 3,552 3,528 3,502 3,472 3,438 3,484
Line Amps 19.50 21.60 25.50 30.10 37.40 45.00 53.70 42.00
@@DavidandHarrison Looking up specs for that motor it looks like it is 65 A to 85 A with a really high starting torque, which is to be expected. At 240VAC nominal, that's 15kW to 20.4kW for locked rotor torque. The soft start would give it 30% to 60% less locked rotor current, so we are looking at 6.24kW 14kW.
I think that what I have seen some of the others on here post is that it is going to need oversized starting capacitors like an HV/AC compressor would use and a change to the pulley sizes. That is assuming just putting a pressure relief valve for start up doesn't fix the problem.
@@KnightsWithoutATable Thats why I was thinking of a slipping belt clutch system like many ride on lawn mowers or a straight electric pulley clutch that would give zero external load on the motor at start. Pressure relief valves would not do that you would still have plenty of rotational inertia to overcome to get the compressor spinning. In that way a smaller pulley should not be required . The generator is plenty big enough to run the 100% load. Just need to get the motor closer to synchronous speed prior to loading it.
@@DavidandHarrison A motorcycle clutch might be able to be used. Add in a flywheel on the motor side and then you would have the rotational inertial to prevent it from getting into a locked rotor state.
I like the idea of a pulley reduction, a mechanical solution that is more kind on your electrical equipment
Compressor, reciprocating versus a scroll compressor(hvac). try telling it that its starting a motor not an AC compresor. Take the belt off and see how the motor behaves. Spin compressor by hand feel how it turns. Check start and run caps. Just a couple thing fell out my brain. Former hvac, electric, plumbing business owner retired.
I think it's called "single phase" for 220v because they hit zero at the same time just 180 degrees out of phase with each other in terms of + and -. 3 phase hits zero at three different times.
I have to agree with venting the compressor until the motor is up to speed. If it works you could wire a time delay motorized ball valve to close the bleed slowly ramping the load up slowly.
Doug, Maybe this will help you. The wires are not the phases. The phases are between the wires. What is between 2 wires, is 1 phase. Add another wire and you have 3 wires, and by having this third wire, you add another 2 phases, for a total of 3. Phase A is between legs 1 and 2. Phase B is between legs 1 and 3. Phase C is between legs 2 and 3. If you are using 230v, there is no neutral to contend with. Wipe it from your mind. It is a 120v thing when center tapping 1 phase is used. Make sense ? ? ? --Doozer
Doug- Another comment,,, Your single phase scuba compressor motor is capacitor start. This motor is actually a 2 phase, 90° phase angle motor. (not like 3 phase, with a 120° phase angle.) How it starts, is a centrifugal contact switch brings in the starting capacitor(s) and the starting windings. This capacitor creates a 90° phase angle shift in the electrical current being supplied to the start winding. The run winding is just receiving regular current, without the time delay of the capacitor. When I say time delay, it delays the sine wave of the AC current, because there is a time sequence associated with charging the capacitor each time the AC sine wave crosses zero time reference, when the current switches form + to - and back and forth... So this capacitor created another delayed AC waveform. In the motor coils, during starting, you have basically 2 coils that buck each other magnetically. This AC oscillation causes constant magnetic attraction and repulsion between the coils, and it crates rotation in the rotor. Single phase alone can run a motor if it is spinning and the rotor lag between rotor speed and syncronous speed are enough to generate induction in the shorted shaded poles of the rotor. But you need another phase when the motor is not running to create enough induction in the shorted shaded poles of the rotor to get it moving.
I said all that to say this... I notice your generator voltage was dropping during the starting sequence. I saw 150v on your meter. I believe with your lower voltage from the generator (not having enough amps) you might need larger farrad capacitor to be able for it to create that 90° phase shift at the lower voltage that you are experiencing. Also, I think your centrifugal start switch is cutting the start capacitor (and start winding) out of the circuit too soon. The rpm falls, an the cap cuts in and then out again. This cycle is bad. You can install a stronger spring on the centrifugal switch, or install a push button to control the start cap and winding, so you can (and must) be present to start the motor, as in hold the start button until the motor starts. Or you can run the cap and start winding through a current sensing relay, that keeps the start windings and cap engaged until the motor current drops below a set level, meaning the motor has started. I know I am trying to communicate a lot, but I think you have a complex problem there to be solved. And yes, make sure the unloader works, but I assume there is zero pressure in the tanks right now, so it should not matter for a cold start. Hope this helps ---Doozer
You might try hooking up the motor ,bypassing relays,just make sure it's on a circut breaker!
Crazy thought but what about a pto drive shaft from generator motor to the compressor?
It’s called split phase. Or 220. They are 180 degrees out from each other to neutral.
Add caps for start and run if necessary.
Put a tap/valve on the output of the compressor to the tank fill point venting to atmosphere on start up then close tap/valve once motor is up to speed, this should get you going
Might be helpful to ad some capacitors with a centrifugal disconnect switch to help on the heavy power draw at start. I know is kind old school but sometimes simple stuff last longer than technology
A smaller pulley should cut the work down to an acceptable level. I think you're on the right track
That pully is that size for a reason to run the comp at the correct revs, the CFM will be a lot slower.. Like his genny it runs at x amount of revs to make10kva run it slower you get less.
I believe they call in 220 instead of 2 phase is that they are only caring about the electrical potential.
Compression release is what you need. You are an inspiration. Hold Fast
Unfortunately there is no compression without tanks being attached.
Seems like it needs unloader valves. Allows the compressor to start without compressing air. Then when it's up and running. Unloader valve stops bleeding air to atmosphere and sends it to tanks. I don't think just opening the tank fill valve would work as it is a multi stage compressor.
When the pump starts, there should be very little if any load on it. If there is, then there's air pressure in the tank. I wonder if an NC solenoid valve in series with a check valve could be installed at the pump head(s). When the pump starts, the solenoid valve opens allowing air to escape from the pump head allowing it to come up to speed. Then it would close. There's usually some kind of head pressure release valve on the pressure switch.
soft starters are good for ... some things not needing a big start up torque....like a band saw , fan (but pulls big AMPS at start) here u would need some kind a "booster" to get it started (big compression makes it hard to start ...) smaller pulley will help... some. A clutch would be helpful (like a fly wheel auto clutch ) OR.... some decomp valve on that compressor... when it span up closing it, so at startup almost no torque is needed
How about an even wilder idea. Install a similar size electric motor with a flywheel on it and start that first. Once the flywheel is up to speed kick on the compressor and the running motor will be able to supply a current back into the system to help start the compressor. When calculating short circuit currents for electrical distribution systems in plants with large motors we include the contribution from the running motors in the plant. They add to the available short circuit currents at the distribution panels.
Smaller pulley on the motor would help tremendously, otherwise an unloader would be best, however something that shut off the air supply to the intake of the first stage might be best as it would cause it to draw a vacuum instead of attempting to pump, its atleast worth investigating.
Another good but not cheap option would be a 3 phase motor, much higher starting torque and a vfd.
How about a compressor bypass valve, get it going the shut it so it can build pressure that's what we do on the large natural gas compressors. It's just a valve between the intake and discharge pipes.
How about putting a loading valve on the compressor output that you control manually. Once the motor is up to speed, THEN load the compressor to compress the air?
I suggest checking the capacitors in the Baldor motor and verify one hasn’t popped or the wire vibrated loose. A bad cap will make a motor do weird shit.
It runs fine off grid power.
@@SVSeeker he's got a point - if there's multiple caps in there and one is bad or connection loose then it may run fine on grid power but be too much to start on genny. It could also consufe the hell out of an intelligent soft-starter.
It's 2 minutes for a quick visual check, so it's not worth not doin.
yes folks, consufe is a real word
Call the motor maker and ask about giant start Capacators. no soft start rather a hard fast start. do not change the pullys! It wont work worth a shit at high pressure filling and times will go up. Also try with shore power to ensure it even runs with good power.
Your generator needs the capacators for the required in rush of amps.
05:36 Andrew & Kelly New Zealand...it is written in that ply wood floor behind the starter ...
Hi great vids, me being old n simple haa a diesel moter ,instead of a generator to run compressor sounds nice an simple
I always thought compressors need a bigger jolt to get started. Not a softer one. I would size up my leads that’s the cheapest try. After that I would just get more power if possible