Why does the Process Drive run at 1800 rpm when a 4-20mA signal is applied on a 0-10Vdc input?

Issue:
Process drive running at 1800 rpm when a 4-20mA signal is applied on a 0-10Vdc input.

Resolution:
This is a normal behavior of the drive.
Basically an external 4 … 20mA set point device (PLC, PID controller, anything else) tries to force the current through the burden resistor.
When the analog input of the drive is configured to 4 … 20mA (AI1 Type [AI1T] = Current) a burden resistor is connected into the loop -> and everything works fine.
When the analog input of the drive is configured to 0 … 10V (AI1 Type [AI1T] = Voltage) there is no burden resistor in the loop. As a result the 4 … 20mA set point device is not able to force a current and the output of this device goes to its maximum voltage – typically 12V … 16V -> and the drive accelerates to the maximum speed [HSP].
With the factory setting of 100% slip compensation (parameter [SLP] = 100%) the drive always tries to reach the synchronous speed of the motor (1800 rpm).
If the motor shall not run more than the nominal speed (17xx rpm), the slip compensation must be set to 0%.

Publicado para: Schneider Electric Mexico