Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 68)

2-38 Drive Installation
7000A-RM001A-EN-P – January 2011 7000 “A” Frame
Power and Control Wiring Drive line-ups (i.e. Drive and Input Starter) which are delivered in
two or more sections, for ease of handling, will require that the
power and control wiring be re-connected. After the sections are
brought together, the power and control wiring is to be re-connected
as per the schematic drawings provided.
Control Cables
Control cable entry/exit should be located near the terminal block
'TBC' – the customer's connections are to be routed along the
empty side of the TBC terminals. These terminals are sized to
accept a maximum #14 AWG. The low voltage signals (includes
4-20mA) are to be connected using twisted shielded cable, with a
minimum #18 AWG.
Of special concern is the tachometer signal. Two tachometer inputs
are provided to accommodate a quadrature tachometer (senses motor
direction). The tachometer power supply is isolated and provides
+15 Volts and a ground reference. Many tachometer outputs have an
open collector output, in which case a pull-up resistor must be added
to ensure that proper signals are fed to the system logic. (Refer to
Appendix A "When is a Tachometer Required?" to see if one
needs to be supplied.)
Low voltage signals are to be connected using
twisted shielded cable with the shield connected
at the signal source end only. The shield at the
other end is to be wrapped with electrical tape
and isolated. Connections are to be made as
shown on the electrical drawings (ED) provided.
Encoder Installation Guidelines
The most frequent problems encountered when transmitting an
encoder’s signal(s) to the drive are signal distortion and electrical
noise. Either of these problems can result in a gain or loss of encoder
data counts (quadrature encoders) or corrupt positional data (absolute
encoders). Many of these problems can be avoided by applying good
installation and wiring practices. This section is a general guideline
and recommended practices for field installed equipment. It applies
to either encoder board and both quadrature and absolute encoders.
I M P O R T A N T I M P O R T A N T