V20 A501 current limiting after "quick Commission"

Hi,

I have two separate V20 400v 1.5kW drive with identical 1.5kW motors. I have followed the guided "quick commissioning", the only parameters that needed to be adjusted were the connection macro (set to control from terminals) and application macro (set to centrifugal pump). I also set the minimum Hz to 5Hz.

Both VFDs are doing the exact same thing: the output voltage doesn't go above 141v and at 25Hz I get A501, output current is 5.19A (motor rated amps is 3.19A) and the drive will not increase in speed regardless of the A1 input.

I have tried multiple different combinations of application macros, lowering boost settings to zero, set the parameter 1900 to complete standstill identification of parameters. I've factory reset many times to start over. I've checked the measured stator ohms against that set in P0350, it was off by about 1ohm but changing this made no difference.

Are motors connected for 400 Volts, star or delta as necessary?

As you have tried, the drive should run the motor over the full range from default, can you then replace the motor cable as a temporary measure?

This is the same snag for both drives?

Tractor

Hi Tractor,

I did fail to mention before that I did test the motors and cables for short/ ground fault. I've also swapped the motors from one drive to another with no improvement. Strange that I have two identical set ups, all new gear commissioning for the first time. Obviously I've missed some small detail in the config that is causing this to happen on both setups.

cheers,

Hi, this is a puzzle….

You have done all I would have done, a minimal setup from default will / should work…

Swapped the motors, and cables..

The motor, is this star or delta for 400 volts?

What is the V20 part number?

Tractor

The motor and drive combination is good.

Thinks:

If you disconnect the motor and run the drive, does it go to 50Hz?

The motor connection, could the internal wiring of the motor be incorrect. The motor, is 230 Volt for Delta, and 400Volt for star connection, I assume?

Resistance for delta connection as 1X per phase, and star connection 2X per phase?

(X being whatever the resistance of one coil might be)

The motor is disconnected from the mechanical load for testing?

Tractor

Hi Tractor,

I definitely have the motors wired in delta, the name plate on the motors shows that they can be wired in star for 230v or delta for 400v.

it did cross my mind earlier that not having the motors connected to a mechanical load might be an issue but I have never experienced this before. could it be that I just need to connect them to the mechanical load and the problem will go away??

cheers,

Still puzzling this one, being disconnected from the mechanical load I doubt, will cause this snag.

Ramp times are not too short?

Does it ramp up if the motor wires are disconnected from the V20, ignoring the ‘loss of load’, fault code?

Both drives are behaving in the same manner, if the V20 were at fault, this would indicate a production problem, which would have been picked up by now by Siemens.

Do you have an old motor on the shelf to substitute as a temporary basis, struggling not to suggest a way out of this as you can see?

Please keep us posted on the outcome, the client will be ‘beating a path to your door’ by now i guess.

Tractor

Thoughts, the switching frequency P1800….. this is at default of at least a low value???

Tractor

Hey Tractor,

you actually nailed it earlier. I found a gearbox to connect to the motor as I had them free spinning just for commissioning and as soon as they had a little bit of load, just a reduction gearbox nothing connected on the output side of the gear box, they worked perfectly.

I had the thought yesterday but dismissed it. I’ve never seen a drive do that before. With no motor connected the drive will start and run as if it does and out put is normal which is strange too, would have expected a “no load” or similar fault.

thanks for the assist mate.

Shannon.