We have done the same with one of the screw compressor of 30HP. I installed PT at the output which is wired with the PID controller tuned against the requirement of air in the system. The inside pressure switch is some sort of bypassed. The system is running smoothly between 30 Hz to 50Hz.
Hello, Assad can you provide a detail which VFD use and parameter how to configure in a VFD of a PID control for air compressor. (because I want to control my air compressor, not at a fixed speed. ( not on or off) it can be controlled by the demand of pressure like pressure increase some point then VFD decrease a speed 10% and vice versa operation.
I wonder if you could program the VFD to run in a constant power mode. So it will increase the frequency and the load up to a maximum when the tank pressure is low. Automatically increasing CFM without any 'complex' feedback loop.
It entirely depends on the amperage you expect (and the motor is rated to) draw. Look up an amperage wire gauge chart and check the ratings plate on the motor for amperage
so what is the problem if the compressor auto cuts off without wiring the air pressure switch through the VFD, would it under voltage and not restart up when the pressure fell?
dregenius, would you share VFD Mfg/model info and cost? I’m working out whether it’s worth it to go VFD or just buy a new single phase motor for a 5HP IR 2340L5-V...
I noticed 3 phase motors are a little cheaper than single. A single to 3 phase vfd will give you more options and tons of control. Some even have over current protection and other features to keep motor happy...
Any update on what you did? I bought a 10 hp VFD to do this for my 3phase 5 hp champion compressor... it was 200 bucks. Probably gonna be another 100 to wire it all up. But I guess we could just buy a 1 phase 5 hp motor too...
I have a newer Hunan VFD and perhaps a different 7.5KW model. There is no FWD or DCM. I can program a connection such as "S1" to FWD. There is a GND or COM terminal. Either of those should work. However, no matter what I do, when I hit "run" the compressor will run whether or not the pressure switch is open or closed. If I program S1 to pause running, it will stop power to the motor when the circuit is closed and provide power when the circuit is open. This is exactly the opposite of what I need. Any insights on how to get the VFD control circuit to run on closed circuit and pause on closed circuit?
Gary, there are two settings on mine for this. I have the same black box just a different makeup, typical import VFD. One setting is to select the external input as a means to turning the output to the compressor motor on and off, (vs. using the keypad manually) and the other setting was to select whether or not it could be restarted again automatically. That second setting was critical, because until I had both of them enabled it wouldn't allow a motor output. Make sure you have an ESTOP wired in if you do this though, there is no way to stop the motor from the VFD once you do this, it literally locks you out of everything except speed control! These drives are great for the price but the documentation is always lacking as in with most imports. This is why I tend to stay with the known brands like Teco because the manuals are so thorough and you're not setting up blindly.
I figured it out. I ran a control wire from the pressure switch to the S1 pin and the COM pin. S1 is programmed to allow the VFD to run when there is continuity and stop when there is not. The COM is the common ground. So, when the pressure switch is closed (below the low pressure turn on setting) the contacts are close and their is continuity and the VFD will run. When the pressure exceeds the high pressure limit the pressure switch opens and the continuity is broken and the VFD stops. Now there is one trick that you have be aware of and this had me stumped for a long time. The VFD has a safety protocol built in such that if there is continuity on S1 when the VFD is first turned on it will NOT start! This is to prevent an unexpected or unsafe start. So, what I did was wire a simple manual open and close switch on one of the control wires. I used a light switch. Thus when I start the VFD because I am going to be using the compressor and the pressure is low/pressure switch closed I go ahead and let the VFD power up. After is it powered up I open and close my light switch and the VFD powers up the compressor. If I leave the VFD on then I don't have to do this again but it is often weeks between needing to use the compressor so I end up doing this as part of my regular start up cycle. The VFD and compressor have been working like a charm.
I figured it out. I ran a control wire from the pressure switch to the S1 pin and the COM pin. S1 is programmed to allow the VFD to run when there is continuity and stop when there is not. The COM is the common ground. So, when the pressure switch is closed (below the low pressure turn on setting) the contacts are close and their is continuity and the VFD will run. When the pressure exceeds the high pressure limit the pressure switch opens and the continuity is broken and the VFD stops. Now there is one trick that you have be aware of and this had me stumped for a long time. The VFD has a safety protocol built in such that if there is continuity on S1 when the VFD is first turned on it will NOT start! This is to prevent an unexpected or unsafe start. So, what I did was wire a simple manual open and close switch on one of the control wires. I used a light switch. Thus when I start the VFD because I am going to be using the compressor and the pressure is low/pressure switch closed I go ahead and let the VFD power up. After is it powered up I open and close my light switch and the VFD powers up the compressor. If I leave the VFD on then I don't have to do this again but it is often weeks between needing to use the compressor so I end up doing this as part of my regular start up cycle. The VFD and compressor have been working like a charm.
I know exactly what you're talking about. On mine however there is a separate setting for this. Without it enabled you are stuck on first startup as you have seen. You probably don't need the jumper if you have this on your VFD. Can you post a link to the manual for your unit?
Hi, i have 10hp air compressor i bought the VFD and received it yesterday, my motor is 3phase to single phase with the VFD. Is it ok just using only the RT for single and UVW for my motor? Then for pressure switch, i did not touch it what will happen if i will not connect to VFD for pressure switch?
What kinda amperage are you pulling from that single phase? I'm considering doing the same thing with a 5hp champion compressor... but I only have a single 240v receptacle in my garage thats wired to a 30 amp breaker.
I have the 10hp version of this vfd and a square d pressure switch, other than the reverse lockout what settings did you have to change when programming it? Also you dont need any supply power lines going to the pressure switch?
I hooked mine up exactly the same as you did and it did not work. Any suggestions? It runs manually turning it on off fine but programming it to accept commands from the board doesn't seem to take.
This is exactly what I needed to see. I had installed a magnetic contactor and it certainly did NOT like the VFD output. I did have one question, however. Some forum discussions say that 2 phase 220V input does not require 2 times the output on the VFD, but if 3 phase in is used it will require approximately double the VFD capacity. (startup amps) So is double the VFD required, say for example, a 10 h.p. VFD for a 5 h.p. 3 phase motor if using 3 phase input? Just curious.
I believe that is true. Not exactly double... and I think you alleviate some of that by ramping it up slowly... but true in principle. However... and I need to read some more on my R15 pump... if you ramp too slowly youre running the pump without lubrication for some time. My pump has a unloading valve... so I dont think it will be too hard on it. But I'm not sure.
@@ChristianNeff I gave up on the VFD, and moved up to a 7.5 h.p. 1750 Baldor motor fed by my 20 h.p. RPC last summer. I've only had one slight problem with it since then, trying to start it in sub-freezing weather. I let it warm up 10 degrees and it started up fine. I only gave up on it because it burned up, since it was only rated for 5 h.p. and needs much more than that at startup. The 10 h.p. VFDS are not cheap.
I have a similar setup but I’m having an issue. I understand that the motor is supposed to be wired directly to the VFD with nothing in between. I did this by bypassing the little “control box” for the compressor. When I do this, I can get the motor to run well. However, the compressor won’t make more than 50psi unless the unloader valve is energized while the motor is running. I’m assuming the unloader valve gets energized through the control box that I bypassed. So, here’s my issue... how do I wire directly to the motor AND energize the unloader valve?
I was hoping you would show it running. Mine has a ramp (5second startup) and runs slower to ramp up to 60hz. I believe this conflicts with your splash lubrication theory and may be hurting the compressor. Also cannot get the vfd to run when it has a load. I tried unloader removing pressure from head, everything.
That is quite true about the speed affecting splash lubrication. Some older compressor designs (Quincy comes to mind as being known for this particularly) use an oil pump and pressurized lubrication, which shuold be relatively immune to low speed lubrication issues (within reason of course). Regardless, I would imagine a few seconds of slower speed during startup is unlikely to pose any issue on any compressor, especially if your unloader valve is working correctly - I might even go so far as to surmise that having pressure on top the piston(s) in a compressor constantly while it's not turning is likely to do much more harm (from squeezing out the oil film on the journals and bearings) than low speed startup would.
Is this motor still running? I need to do the same here. The 2 wires in the pressure switch are in Line or motor terminals? Do I need further protection for the VFD and all system?
It's been running great for over a year and a half now under "heavy residential" use. It sounds like you're asking how the pressure switch is wired... the pressure switch does not control the motor directly or handle any kind of high voltage signals at all, the pressure switch is used to command the VFD to run the motor as follows: VFD has a *low voltage signal-level* terminal labeled "FWD" which when shorted to ground will cause the VFD to run the motor. The pressure switch is connected to ground on one side, and the FWD terminal on the other side, so that when the pressure drops, the switch grounds the FWD terminal on the VFD. Note that in my case, "FWD" was the correct direction to turn the pump, but make sure you are running your compressor the correct direction - take note of arrows or fan blades on the pump pulley. You may have to use the "REV" terminal to run the motor instead of "FWD" like I did. Locking out the wrong direction (by using the menu system on the VFD) is a good idea to prevent the system from in the future accidentally being set to run in reverse without noticing. If that were to happen, compressor lifespan would likely be limited.
So far so good. Only been installed a couple months but no major problems. I did choose a way-oversized Chinese VFD since it'll be starting under some load - 10hp VFD for a 5hp motor, and of course never use a motor contactor - use the pressure switch to ground the "fwd" terminal on the VFD or similar. I also locked out reverse and set maximum frequency to 60hz. Ramp time is something like 5-7 seconds or so.
Hi Guys it's been a year since you have a good conversation. I would like to ask if you have tried programming the vfd using its multi step function (not only ON and OFF). That is if i have a continuous demand of air, i need a max pressure and hence max frequency. But if the air demand is at average, say the frequency will be at 40Hz. In short, the compressor will never be OFF (it will run at varying speed or frequency) unless the air demand is zero hence the pressure switch will trigger to its set pressure.
We did investigate this, however there's actually some good reasons not to do this: the compressor relies on splash lubrication, and below a certain speed (usually listed as minimum speed on the specifications tag) the oil paddle on the connecting rod will not be moving fast enough for the oil it splashes to reach all components inside the compressor. So although it may seem counterintuitive, running a compressor *too slowly* can actually kill it pretty quickly.
We have done the same with one of the screw compressor of 30HP. I installed PT at the output which is wired with the PID controller tuned against the requirement of air in the system. The inside pressure switch is some sort of bypassed. The system is running smoothly between 30 Hz to 50Hz.
Hello, Assad can you provide a detail which VFD use and parameter how to configure in a VFD of a PID control for air compressor. (because I want to control my air compressor, not at a fixed speed. ( not on or off) it can be controlled by the demand of pressure like pressure increase some point then VFD decrease a speed 10% and vice versa operation.
I wonder if you could program the VFD to run in a constant power mode. So it will increase the frequency and the load up to a maximum when the tank pressure is low. Automatically increasing CFM without any 'complex' feedback loop.
I am going to be using this same vid on my compressor hookup this weekend. Do you recall what gauge wire you used from your plug to the VFD input?
It entirely depends on the amperage you expect (and the motor is rated to) draw. Look up an amperage wire gauge chart and check the ratings plate on the motor for amperage
so what is the problem if the compressor auto cuts off without wiring the air pressure switch through the VFD, would it under voltage and not restart up when the pressure fell?
It will fry the vfd
dregenius, would you share VFD Mfg/model info and cost? I’m working out whether it’s worth it to go VFD or just buy a new single phase motor for a 5HP IR 2340L5-V...
I noticed 3 phase motors are a little cheaper than single. A single to 3 phase vfd will give you more options and tons of control. Some even have over current protection and other features to keep motor happy...
Any update on what you did?
I bought a 10 hp VFD to do this for my 3phase 5 hp champion compressor... it was 200 bucks. Probably gonna be another 100 to wire it all up.
But I guess we could just buy a 1 phase 5 hp motor too...
I have a newer Hunan VFD and perhaps a different 7.5KW model. There is no FWD or DCM. I can program a connection such as "S1" to FWD. There is a GND or COM terminal. Either of those should work. However, no matter what I do, when I hit "run" the compressor will run whether or not the pressure switch is open or closed. If I program S1 to pause running, it will stop power to the motor when the circuit is closed and provide power when the circuit is open. This is exactly the opposite of what I need. Any insights on how to get the VFD control circuit to run on closed circuit and pause on closed circuit?
Hi did you solve this problem? I'm having pretty much the exact same issue.
Gary, there are two settings on mine for this. I have the same black box just a different makeup, typical import VFD. One setting is to select the external input as a means to turning the output to the compressor motor on and off, (vs. using the keypad manually) and the other setting was to select whether or not it could be restarted again automatically. That second setting was critical, because until I had both of them enabled it wouldn't allow a motor output. Make sure you have an ESTOP wired in if you do this though, there is no way to stop the motor from the VFD once you do this, it literally locks you out of everything except speed control! These drives are great for the price but the documentation is always lacking as in with most imports. This is why I tend to stay with the known brands like Teco because the manuals are so thorough and you're not setting up blindly.
I figured it out. I ran a control wire from the pressure switch to the S1 pin and the COM pin. S1 is programmed to allow the VFD to run when there is continuity and stop when there is not. The COM is the common ground. So, when the pressure switch is closed (below the low pressure turn on setting) the contacts are close and their is continuity and the VFD will run. When the pressure exceeds the high pressure limit the pressure switch opens and the continuity is broken and the VFD stops. Now there is one trick that you have be aware of and this had me stumped for a long time. The VFD has a safety protocol built in such that if there is continuity on S1 when the VFD is first turned on it will NOT start! This is to prevent an unexpected or unsafe start. So, what I did was wire a simple manual open and close switch on one of the control wires. I used a light switch. Thus when I start the VFD because I am going to be using the compressor and the pressure is low/pressure switch closed I go ahead and let the VFD power up. After is it powered up I open and close my light switch and the VFD powers up the compressor. If I leave the VFD on then I don't have to do this again but it is often weeks between needing to use the compressor so I end up doing this as part of my regular start up cycle. The VFD and compressor have been working like a charm.
I figured it out. I ran a control wire from the pressure switch to the S1 pin and the COM pin. S1 is programmed to allow the VFD to run when there is continuity and stop when there is not. The COM is the common ground. So, when the pressure switch is closed (below the low pressure turn on setting) the contacts are close and their is continuity and the VFD will run. When the pressure exceeds the high pressure limit the pressure switch opens and the continuity is broken and the VFD stops. Now there is one trick that you have be aware of and this had me stumped for a long time. The VFD has a safety protocol built in such that if there is continuity on S1 when the VFD is first turned on it will NOT start! This is to prevent an unexpected or unsafe start. So, what I did was wire a simple manual open and close switch on one of the control wires. I used a light switch. Thus when I start the VFD because I am going to be using the compressor and the pressure is low/pressure switch closed I go ahead and let the VFD power up. After is it powered up I open and close my light switch and the VFD powers up the compressor. If I leave the VFD on then I don't have to do this again but it is often weeks between needing to use the compressor so I end up doing this as part of my regular start up cycle. The VFD and compressor have been working like a charm.
I know exactly what you're talking about. On mine however there is a separate setting for this. Without it enabled you are stuck on first startup as you have seen. You probably don't need the jumper if you have this on your VFD. Can you post a link to the manual for your unit?
Hi, i have 10hp air compressor i bought the VFD and received it yesterday, my motor is 3phase to single phase with the VFD.
Is it ok just using only the RT for single and UVW for my motor? Then for pressure switch, i did not touch it what will happen if i will not connect to VFD for pressure switch?
What kinda amperage are you pulling from that single phase?
I'm considering doing the same thing with a 5hp champion compressor... but I only have a single 240v receptacle in my garage thats wired to a 30 amp breaker.
I have the 10hp version of this vfd and a square d pressure switch, other than the reverse lockout what settings did you have to change when programming it?
Also you dont need any supply power lines going to the pressure switch?
I’m trying to workout the same thing. Did you manage to figure it out by any chance?
I hooked mine up exactly the same as you did and it did not work. Any suggestions? It runs manually turning it on off fine but programming it to accept commands from the board doesn't seem to take.
This is exactly what I needed to see. I had installed a magnetic contactor and it certainly did NOT like the VFD output. I did have one question, however. Some forum discussions say that 2 phase 220V input does not require 2 times the output on the VFD, but if 3 phase in is used it will require approximately double the VFD capacity. (startup amps) So is double the VFD required, say for example, a 10 h.p. VFD for a 5 h.p. 3 phase motor if using 3 phase input? Just curious.
I believe that is true. Not exactly double... and I think you alleviate some of that by ramping it up slowly... but true in principle.
However... and I need to read some more on my R15 pump... if you ramp too slowly youre running the pump without lubrication for some time. My pump has a unloading valve... so I dont think it will be too hard on it. But I'm not sure.
@@ChristianNeff I gave up on the VFD, and moved up to a 7.5 h.p. 1750 Baldor motor fed by my 20 h.p. RPC last summer. I've only had one slight problem with it since then, trying to start it in sub-freezing weather. I let it warm up 10 degrees and it started up fine. I only gave up on it because it burned up, since it was only rated for 5 h.p. and needs much more than that at startup. The 10 h.p. VFDS are not cheap.
I have a similar setup but I’m having an issue. I understand that the motor is supposed to be wired directly to the VFD with nothing in between. I did this by bypassing the little “control box” for the compressor. When I do this, I can get the motor to run well. However, the compressor won’t make more than 50psi unless the unloader valve is energized while the motor is running. I’m assuming the unloader valve gets energized through the control box that I bypassed. So, here’s my issue... how do I wire directly to the motor AND energize the unloader valve?
Aren't unloader valves centrifugally controlled? At least I think they are in some cases.
I was hoping you would show it running. Mine has a ramp (5second startup) and runs slower to ramp up to 60hz. I believe this conflicts with your splash lubrication theory and may be hurting the compressor.
Also cannot get the vfd to run when it has a load. I tried unloader removing pressure from head, everything.
That is quite true about the speed affecting splash lubrication. Some older compressor designs (Quincy comes to mind as being known for this particularly) use an oil pump and pressurized lubrication, which shuold be relatively immune to low speed lubrication issues (within reason of course). Regardless, I would imagine a few seconds of slower speed during startup is unlikely to pose any issue on any compressor, especially if your unloader valve is working correctly - I might even go so far as to surmise that having pressure on top the piston(s) in a compressor constantly while it's not turning is likely to do much more harm (from squeezing out the oil film on the journals and bearings) than low speed startup would.
Good soft starer
Get a VFD with a Knob on it so you can just turn the knob and set the speed.
How many hp this compressor?
is it still working?
Is this motor still running? I need to do the same here. The 2 wires in the pressure switch are in Line or motor terminals? Do I need further protection for the VFD and all system?
It's been running great for over a year and a half now under "heavy residential" use. It sounds like you're asking how the pressure switch is wired... the pressure switch does not control the motor directly or handle any kind of high voltage signals at all, the pressure switch is used to command the VFD to run the motor as follows: VFD has a *low voltage signal-level* terminal labeled "FWD" which when shorted to ground will cause the VFD to run the motor. The pressure switch is connected to ground on one side, and the FWD terminal on the other side, so that when the pressure drops, the switch grounds the FWD terminal on the VFD. Note that in my case, "FWD" was the correct direction to turn the pump, but make sure you are running your compressor the correct direction - take note of arrows or fan blades on the pump pulley. You may have to use the "REV" terminal to run the motor instead of "FWD" like I did. Locking out the wrong direction (by using the menu system on the VFD) is a good idea to prevent the system from in the future accidentally being set to run in reverse without noticing. If that were to happen, compressor lifespan would likely be limited.
Thank you
How has the VFD been working. I have been looking at getting one for the same exact setup.
So far so good. Only been installed a couple months but no major problems. I did choose a way-oversized Chinese VFD since it'll be starting under some load - 10hp VFD for a 5hp motor, and of course never use a motor contactor - use the pressure switch to ground the "fwd" terminal on the VFD or similar. I also locked out reverse and set maximum frequency to 60hz. Ramp time is something like 5-7 seconds or so.
smoke is very hard to put back in can take hours
thanks for making this video
Are you converting 1 phase to 3 phase with the vfd?
Can you post a link to your vfd model?
Hi Guys it's been a year since you have a good conversation. I would like to ask if you have tried programming the vfd using its multi step function (not only ON and OFF). That is if i have a continuous demand of air, i need a max pressure and hence max frequency. But if the air demand is at average, say the frequency will be at 40Hz. In short, the compressor will never be OFF (it will run at varying speed or frequency) unless the air demand is zero hence the pressure switch will trigger to its set pressure.
I ask this cause i needed help.. I want my compressor run automatically depending on air demand. Thank you
We did investigate this, however there's actually some good reasons not to do this: the compressor relies on splash lubrication, and below a certain speed (usually listed as minimum speed on the specifications tag) the oil paddle on the connecting rod will not be moving fast enough for the oil it splashes to reach all components inside the compressor. So although it may seem counterintuitive, running a compressor *too slowly* can actually kill it pretty quickly.