Wiring a VFD for a Quincy Air Compressor

[Iyanola]

Hey Guys, I bought a Quincy Air compressor with a 230v 60Hz 5HP motor. Trouble is the electrical frequency in my country is 50Hz and the compressor was advertised as having a 50Hz motor. To remedy this I bought a VFD in order to up the operation of the motor to 60Hz because the motor runs too hot and trips the thermal switch. I wired up the VFD to the motor and it does start, however when it has start after the pressure switch brings it back on, it throws an overcurrent error code. There’s a bus bar above the power connection for the VFD but it didn’t come with any clear instructions has to how to wire it up. I have a hunch this would solve the issue but I’m not sure how to wire it up. Could anyone help or give guidance?

tps://imgbox.com/UXYISUt6
imgbox - fast, simple image host
imgbox - fast, simple image host

 

[Iyanola]

imgbox - fast, simple image host Picture of the data plate of the motor

 

[mksj]

Basically an HY generic VFD, they often over rate the VFD's outputs and the terminals do not support the amperage. Most do not last when running a compressor, unless significantly over sized. Motor should be directly connected to the VFD. The terminals are for external controls, so the pressure switch should be connected to COM and FWD terminals to switch on/off the VFD via the pressure switch (only connected to the VFD run terminals). You will need to adjust the programming parameters for the motor, and also the acceleration is probably too long causing an over current error on start up.


Manual is here:
GK3000 inverter drives model selection

Starting point for suggested parameters, next time include the fault code information, it often will say when the fault occurred and under what conditions.
P0.02 Initial Digital Freq. = 60 Hz
P0.06 Max Output Freq = 60 Hz
P0.07 Base running Freq. = 60 Hz (motor base frequency)
P0.08 Max. Output Voltage = 230V (motor voltage)
P0.09 Torque Boost = 10% (may need to adjust this up in increments of 5%, max. is 30%)
P0,13 Acc/Dec mode = 0 = Linear
P0.17 Acc time 1 = 3 seconds, try between 1-5 seconds)
P0.18 Dec. Time 1 = 2 seconds (best to have no braking and have the compressor stop on its own, see P2.05)
P0.19 upper freq. Limit 60 Hz.
P2.05 Stop Mode = 1 (Free Stop, no braking)

You must set the motor rated parameter in PA: Group Vector Control Parameters to the motor name plate values
PA.01 through PA.05
PA.01 = 230 V
PA.02 = 21.0 A
PA.03 = 60 Hz
PA.04 = 3450 RPM
PA.05 = 2 poles

 

[Iyanola]

I went ahead I did exactly as you described, however the air compressor motor doesn’t run at all, before it gets too full speed it throws a different overcurrent code. Any suggestions?

The error code is e01

Last output frequency was 60Hz
Last set frequency was 38.65
Output current was 47.8A
Output voltage was 141v
DC bus bar was 310v
Module temp was 33

 

[mksj]

It appears to be drawing more current then the VFD can supply, I would try it with the belt off and see if the motor comes to speed and should not run hot. Might try a 5 second acceleration time. Most VFD's have an auto tune ability which allows the VFD to tune itself to the motor parameters. The only other approach might be to set the VFD to V/Hz and tune the V/Hz parameters.

P0.00 would change from 1 sensorless vector control to 0 for V/F control and see if that makes any difference.

 

[SomeoneSomewhere]

The compressor probably has a pressure switch switching a contactor. You need to remove the contactor and set the pressure switch up so it sends a start signal to the VFD.

The colour choices you've made for the motor cable are moderately unusual. Can you show us how they're connected in the motor?

 

[Mr. T]

While it certainly seems like your VFD setting aren’t quite right, I’d be leaning toward a failing motor. There isn’t a ton of difference running a motor on 50hz vs 60hz other than speed. If it was being overloaded at 50hz something seems suspect with it.

 

[Karl_T]

I have a quincy 350 with 7.5 Hp motor.

I used a 10hp VFD and had similar issues. In my case the unloaders were not staying in long enough. I went to an air solenoid valve to the unloaders and controlled it with the VFD, The VFD kept unloaders engaged until motor was at full RPM.

Problem solved for years now.

Understand unloader valves | The Hobby-Machinist

 

[Iyanola]

The compressor probably has a pressure switch switching a contactor. You need to remove the contactor and set the pressure switch up so it sends a start signal to the VFD.

The colour choices you've made for the motor cable are moderately unusual. Can you show us how they're connected in the motor?

There isn’t a contactor, just a pressure switch. I connected the fwd and com to the live and neutral terminals on the pressure switch.

https://we.tl/t-NGmAEkDop3 How it is connected.

 

[Strostkovy]

Have you considered a buck transformer to drop the voltage down to around 190 volts?

 

[Iyanola]

It appears to be drawing more current then the VFD can supply, I would try it with the belt off and see if the motor comes to speed and should not run hot. Might try a 5 second acceleration time. Most VFD's have an auto tune ability which allows the VFD to tune itself to the motor parameters. The only other approach might be to set the VFD to V/Hz and tune the V/Hz parameters.

P0.00 would change from 1 sensorless vector control to 0 for V/F control and see if that makes any difference.

It was already set at V/F control. It’s giving e03 error code.

 

[mksj]

The try sensorless vector control, but I think as Karl mentioned, the short term start-up load can exceed what the VFD can deliver. S0 one would need to unload the head until the motor comes to speed. VFD's current output varies based on the load, and there is a derating for the load and whether running variable toques vs. constant torque. So a 5 Hp rated VFD may work ok with ND, but in HD it may only be able to drive a 3 Hp.

I would also try to see if changing the acceleration time helps at all.

 

[Jraef]

The VFD says it is OK with a single phase motor, but they didn't really tell you that the motor would need to be a Permanent Split Capacitor (PSC) type motor, you likely have a Capacitor Start type. Cap-Start motors place a starting capacitor in parallel to the Start winding of the motor, then it is switched out by a centrifugal switch in the motor once it gets to speed. You cannot use a VFD on that type of motor, because the capacitor will pull more current from the VFD than it is capable of. In addition if you lower the speed to a point below the centrifugal switch operation point (about 80%), the switch closes again and puts the capacitor back into the circuit. So it becomes a race to see if the capacitor charging current damages the transistors in the drive before the harmonics of the VFD damage the capacitor.

In a PSC motor, the capacitor is in SERIES with the winding, so the winding acts as a dampener for the capacitor inrush current and the VFD transistors can handle it. The problem is, PSC motors tend to have less starting torque, so are unsuitable for most compressors unless they are over sized.