My old 1340 GT with VFD

[Aukai]

The owner of my old 1340GT called and asked if I have ever had this problem. Lathe runs in reverse, but in forward the contactor only clicks. What should I have him look for? I suggested checking voltage into the contactor, and out to the motor, but I'm lost....

 

[B2]

Relay clicks.... closes? If so and the voltage is at the input to the relay, then have him check to see if the voltage gets to the VFD. Broken wire or loose connection? This is a bit tricky as usually the VFD is set up to sense on current not voltage. So he may have to remove the wire from the VFD and connect it to a resistor which is connected to ground. Then see if the voltage at relay to resistor changes with the click.

There are too many unknowns as to how the VFD is wired up to make many more guesses. If he wants to know more about how the VFD is wired up he can look on HM at the postings of VFD conversions. Since he has contactors to control his device is not wired up like mine. On the other hand my detailed description, Part II, may be educational for him as it describes how a VFD works. My machine is a PM1440GT, so somewhat, yet not so much so, different from the PM1340GT. By the way Part I will tell him how the original wiring (1449GT), before a VFD was added, was wired up and functioned.

VFD conversion using solid state electronic components.

Good luck.

 

[mksj]

If I recall you did a basic type of install where the contactors operate the VFD inputs. Have him take the VFD wires going to the contator (P24 and Input one and have him connect those two to a switch and see if the VFD will run forward when he closes the switch (spindle needs to be in the stop position. Alternative is to switch the two VFD input wires 1 and 2 at the contactors (or at the VFD) and see if forward now runs with the spindle is in reverse. If it does it sounds like a contactor problem and he can use a different pole, I would also have him check the wire connections for the VFD low level inputs, give a light tug to the input wires at the VFD, and also have him reseat the connections at the contactors.

Contactors are poor conductors for low level signals, in particular if they were previously used for high voltage switching. In addition in humid hot environments they can corrode quicker. You can have him contact me if he needs to dig a bit deeper and that doesn't address the issue. VFD would not loose it programming, either works or it doesn't.

 

[Aukai]

Thank you Mark, if he does not find the problem I will give him your contact email. Is that okay?