Input/Output Signals For Sync Transfer; Up Transfer Implementation - Siemens 6SR41 series Product User Manual

Note
It is not required that all motors connected to a drive configured for synchronous transfer
have matching ratings. If mis-matched motors are implemented, the drive must be sized for
the worst case load. "Smaller" motor loads can be mechanized via parameter read/write
functionality or the NXG Control Multiple Configuration file capability, as described in NXG
Communications Manual (902399) and NXG Control Manual (19001588), respectively. As a
rule, the smallest motor rating should be greater than 50% of the ratings of the largest motor
to ensure feedback signal integrity. When mis-matched motors are used, the proper
configuration file should be active for the subject motor.
Controller Implementation
Refer to the NXG Control Manual, 19001588, for a detailed description of NXG control
configuration required for synchronous transfer.
7.7.3

Input/Output Signals for Sync Transfer

Excluding standard run, stop, and speed reference inputs, synchronous transfer requires
four dedicated input signals and six dedicated output signals to be implemented. These
signals can either be hardwired or implemented as digital control bits over one of the NXG-
supported PLC communication links.
Input Signals to the VFD:
● Up Transfer Request
● Down Transfer Request
● VFD Output Contactor Status
● Motor Line Contactor Status
Output Signals from the VFD:
● VFD Transfer Permissive
● Up Transfer Permit
● Up Transfer Complete
● Down Transfer Permissive
● Down Transfer Complete
● Open Motor Line Contactor
7.7.4

Up Transfer Implementation

Up transfers are accomplished by transferring the motor from the VFD directly to the line. Up
Transfer requires that the VFD synchronize its output to match the voltage, phase angle, and
frequency of the line. This is accomplished by using the drive input line frequency as a
Product User Manual
Operating Instructions, Version AE 12/2009, A5E01454341C
Application Specific Features
7.7 Synchronous Transfer
165