I spoke with Matt Redmond about his vacuum freeze-drier today. He says that the A/C compressor won’t start. He installed a hard-start kit, but it still won’t start. He thinks the 208 V line might have damaged the compressor, as it needs 230 V. Right now, though, we need someone who could look at the A/C compressor and figure out if the motor is burned out or why it won’t start. It would be good if we could meet this Thursday night.
Thank you.
There should be the transformer that was on the old compressor around somewhere. Feel free to use it.
Thanks, but I don’t know if that would fix the problem or not.
I’m afraid that if we can’t get the vacuum freeze-dryer operational in the next few weeks, we are going have to send it back home to its owner.
Is it a custom build or OEM?
As far as I know, it’s OEM. It’s that big, blue metal tube on casters over by VECTOR and Foundry.
I’ve inspected it once, but didn’t take any pictures or mental notes of the make/model. Do you have that info?
The motor is likely permanently damaged if it’s rated at 230 volts and has been run at 208 volts for an extended period of time with a high load. In that situation it’ll draw more amps (at a lower voltage) and overheat usually shorting it out. If a replacement 230 motor is purchased it can be run with a boost transformer which is what Robert is talking about. The other option is get a motor that is rated for 208 volts. If by chance the motor isn’t damaged then simply running it on a boost transformer should make it work as expected.
Model 2452
SN 205
Northstar FreezeDry Mfg, Inc.
Box 439, Pequot Lakes, MN 56472
I tell you what, I’ll come look at it today/tonight. My friend of mine mentioned this to me a month or so ago, I’ve been to busy until last week to look at it. Hopefully it’s just a small wiring issue.
Thanks.
Matt Redmond said he would be available tomorrow, but I plan to be there tonight.
I will be down there in a little bit, maybe the next hour & half or so.
208 did not cause the motor failure. 208 is within +/- 10% of the spec’d 230 (i.e., 230 was the voltage used for spec’ing the motor). Thermal switches would have kicked off if the motor overtemped. For a difficult start application, I presume the motor has a start winding which means it has a start switch. No start booster will help if the start switch is burned out.
Lessons learned from the Husky air compressor tell us to not use transformers on difficult start applications. The problem with the Husky was not 208 but the unreliable unloader on the head. Connecting the transformer only made the problem worse. Start currents can be 600% to 700% above the run current but are only present for a fraction of a second–not long enough to heat the breaker and trip. On the Husky, the head had pressure on it when the unloader malfunctioned and the motor start took longer which tripped the breaker. With the transformer in the circuit, the start current caused a drop across the transformer which lowered the voltage across the motor. In other words, the transformer only made the situation worse. After I removed the transformer on the Husky, it would start fine when I manually unloaded the head but the start switch was in bad shape.
If the condition of the grill on the coils is any indicator, maintenance on the dryer is lacking. Debris in the coils would lower efficiency and cause the motors to overwork. If cooling in the motors is blocked then the motor life is greatly diminished. Also, blockage in the lines causing excessive high-to-low pressure diff will overwork the motor.
Check if it has a start winding and start switch. If replacing the motor, do not use a transformer on a 230 motor but, rather, use a motor rated 208-230 and end this fixation for continually blaming 208.
Ok, looks like an easy fix. The relay is bad, it’s chattering so the coils in the relay probably melted the internal plastic core. I’m going to replace it with an actual contactor. The coil is 120vac. Additionally the start capacitor checked out ok at 162 microfarad. The potential relay looks good, however we need to insure the position of the potential relay since it is position sensitive. I am hoping I can break few & stop by tomorrow to take care of it. The compressor ohms out ok, as well as the motor protector circuit.
Thank you very much for working on this for us!
It’s what the space is about. I will gladly work on something if I have the time to do so. I can’t quite give classes so this is the closest I can do about giving back.
Well the compressor works now. I can’t really speak for anything else since I’m not fully familiar with the operation of the Freeze Dry machine. Easy peasy just replace the relay with a definite purpose 40 amp 2 pole contactor.
I think this deserves a standing ovation.
Not sure how to do that here…
Great job!
Thank you!
I hear a 230 V drop is going to be placed near the pallet storage area west of Machine Shop for the vacuformer. If the freeze drier uses the same supply, it can live beside the vacuformer and neither of them will need to be moved to be used. They cannot both be used at the same time, but that should not be a problem.