Drives Service & Support > 1397 > FAQ

Q? What field supply comes with the 1397 DC Drive, and which one should I use?

A! The standard field supply that comes with the 1397 is a basic “fixed” supply for drives through 60hp@230 volts and through 150hp@460V. 75hp@230V, 200hp@460V and above, come with a regulated field supply as standard. It is therefore not necessary to enter a FS2004, FS2010 or FS2015 into Passport when ordering these drives.

The regulated supply provides field economy and field weakening ability. Field weakening is required to run the motor above base speed,and field economy reduces the field current during idle periods to reduce heat and extend the life of the motor. The basic “fixed” supply does not offer these features.

The third field supply option is the Enhanced field supply. This supply was designed to give the user the ability to increase the field voltage for non standard type motor fields, such as a 240 volt armature motor with a 240 volt field. This supply offers a small amount of field economy but not field weakening.

Q?  Why does my drive fault on an open SCR fault?
A!  This fault has occurred on many 1397 startups, and most of the time it is because the startup has not been done completely. Parameter 36 is a software selection for the CT turns ratio, and is based upon horsepower and voltage. This parameter should be correct from the factory, (because the catalog string of the drive tells the voltage and horsepower), but sometimes it is incorrect. The startup person should verify this value, (see chart in manual for P.036) then after the motor data and other applicable parameters are entered, it is necessary to look under the diagnostic group, and see what the drive indicates for the J18 jumper setting. This is a physical jumper on the regulator board, (main control), and a parameter name. This jumper setting scales the armature current. Then, the next necessary step is to perform the current loop auto-tune, this tunes the drive to the motor. If the fault still persists, increase the value in parameter 167, (Open SCR Sens), this will desensitize the drive, making it more forgiving for AC line three phase imbalance, and load sharing of all SCR firing. This parameter defaults to 0%, assuming perfectly balanced AC lines and SCR firing.  Usually a value of 10% is enough to stop this fault from happening. Lastly, the trip point can be increased in  parameter 168, this defaults to 800.