Rockwell Automation 7000L PowerFlex 7000 Medium Voltage AC Drive C Frame - Marine - Manual (Page 90)

2-60 Drive Installation
7000L-UM302B-EN-P – June 2013 7000 “C” Frame - Marine
3. Keep cable distances as short as is practically possible. Rockwell
Automation‟s recommendation for cable distances are:
a. For the 20B-ENC encoders, the distance should be kept to a
maximum of 65m (200ft). Longer cable distances could
cause excessive surge currents. The operating frequency of
the encoder has no bearing on this recommended distance
due to AC Termination used. However, if the frequency can
be kept so that the cable‟s characteristic impedance is around
348ohms, this will improve the surge currents and may
increase the maximum distance to 100m (330 ft).
b. For the Universal Encoder Interface, the distance can be
extended out to 200 m (650 ft) @ 100 Khz. This distance can
be increased to 500m at frequencies below 55Khz. It is not
recommended to exceed this distance since the voltage drop
across the cable could cause a lower than expected power at
the encoder.
• Unused Inputs
Not all inputs, in either the quadrature or absolute encoders, may be
necessary. For example, the absolute encoder can accept a 12bit
encoder but will work with a lower resolution. Likewise, quadrature
encoders may not utilize the Z track. The following should be used
for unused inputs:
1. 20B-ENC Board. Any unused input should be wired to the
encoder power rail. This also includes the B and B‟ inputs if
using a pulse tachometer. Failure to do this will result in phase
loss warnings and improper operation of the encoder feedback
logic (i.e. missing counts).
2. Universal Encode Interface. When used as a quadrature encoder
interface, the same rule applies as for the 20B-ENC Board.
When operating as an absolute encoder interface, the wiring of
unused inputs is dependent on the position of the POL_QRDNT
jumper. If the jumper is installed, then wire all unused inputs to
ENC PWR, otherwise use ENC COM.
Power and Control Wiring
(cont.)