elm (Customer) asked a question.
I need some help with the parameters to allow normally open switches to start and stop the motor connected to a GS20 VFD. This is an integration project involving a three-phase tire balancing machine.
First, I'm new to Durapulse products but not VFDs. I've integrated several three-phase machines to single phase power.
My integration project is due to the lack of parts available to repair a Coats 950 tire balancer. The original operation of the machine involved using SCRs to start and stop the spindle. The method of stopping was to put the motor in reverse. The controller monitored a position sensor on the motor to control the sequence of the cycle.
The GS20 VFD is mounted and wired up to the balancer. The machine works well using the VFD buttons on the front panel to start and stop the motor. The braking is excellent with a 1000W resistor. The connection to the balancer electronics is through DIN rail mounted optocouplers that take the analog 9 VDC and connects the VFD DCM and DI1 terminals together. The problem is that the motor stops immediately after the turn-on pulse when I need it to stay running. The VFD also needs to stop when it receives a stop pulse at DI2 or which ever terminal can do this function.
I've used NO switches on prior integrations using Hitachi VFDs. I don't remember there being any difficulty in figuring out the wiring or programming. I see that the GS2 mode will allow a momentary non-latching start but I don't know if that mode will give me everything that I need.
I would greatly appreciate advice and recommendations regarding the programming configuration for this use case of pulse start and stop. Regarding safety, kindly appreciate the original design and how there was little in the way of protection from unintended starts. I've already added an EPO to mitigate some of the risk.
Thank you in advance!
Regards,
MCPO Ric
USN Ret.
Without having the manual available to me, in general, when the drive is configured for 3-wire control, the stop input of a drive is wired to a normally closed contact of the Stop pushbutton. From your description it sounds like you have the drive configured for 2-wire control (input high: ON, input low: OFF.) I wish I could give a better answer but I don't have the manual (it's voluminous) on me.
P.S. my dad served in the US Navy during WWII as a signalman. His convoys were attacked on two separate occasions by U-boats. My dad witnessed death he never talked about. Respect.
My grandfather also served in WWII in the Navy. Similarly, he didn't talk about it either - I wish that he had. I read his DD214 and saw that he was in several battles including the attack on Pearl Harbor. It would have been great to share the stories and wisdom.
I may have found a work-around on the momentary start button. I switched the mode to GS2, which does support a NO start switch. I'm not checking to see if all of the other functionality that I need is supported in the GS2 mode.
If you're already using optocoupler relays, add a second for the stop command.(These need to have a changeover contact for this to work).
This will allow the VFD to start with a start signal and not stop until the stop signal is broken from the balancers stop pulse. You may also want an E-Stop through the STO terminals.
I was able to get the drive to start with a NO momentary switch with the configuration you described. However, I wasn't able to get the drive to stop with a second optocoupler. I think the solution for the stop function is going to be a 5V relay thgat opens the DCM signal to DI3.
Take a look at P02.12 Multi-function input mode selection 0000h–FFFFh (0: N.O.; 1: N.C.)
I think you can invert DI3 by setting that to 0004h, although I read a note later in the manual that makes me question if that will work if P2.00 isn't set to zero.
OkiePC,
Thanks for taking the time to read and answer my question. I agree that it isn't possible to invert the DI if P2.00 isn't set to 0.
I've made some progress in GS2 mode. I have the drive starting with a pulse now but stopping is still an issue. The desired solution is to provide a pulse to stop the drive, not unlike the front panel membrane key. Perhaps a relay to open the DCM connection? While not an elegant solution, it will work.
Again, thanks for the reply.