Rockwell Automation 1305 AC Drive, Firmware 1.01-3.00 User Manual User Manual

Page 29

Chapter 2 – Installation/Wiring

2-13

Conduit

If metal conduit is preferred for cable distribution, the
following guidelines must be followed.

1. Drives are normally mounted in cabinets and ground

connections are made at a common ground point in the
cabinet. If the conduit is connected to the motor junction
box and at the drive end, no further conduit connections are
necessary.

2. No more than three sets of motor leads can be routed

through a single conduit. This will minimize “cross talk”
that could reduce the effectiveness of the noise reduction
methods described. If more than three drive/motor
connections per conduit are required, shielded cable as
described above must be used. If practical, each conduit
should contain only one set of motor leads.

ATTENTION: To avoid a possible shock hazard
caused by induced voltages, unused wires in the
conduit must be grounded at both ends. For the
same reason, if a drive sharing a conduit is being
serviced or installed, all drives using this conduit
should be disabled. This will eliminate the
possible shock hazard from “cross coupled” drive
motor leads.

Motor Lead Lengths

Installations with long cables to the motor may require the
addition of output reactors or cable terminators to limit voltage
reflections at the motor. Refer to Table 2.D for the maximum
length cable allowed for various installation techniques.

Table 2.D Recommended Motor cable Lengths

Maximum Cable Length in meters (feet)
with 460V Motor and Insulation Rating
of ...

Drive Rating

Termina-

tion Type

1000V

1200V

1600V

0.37–4.0 kW (0.5–5 HP)

None

12m (40ft)

33m (110ft)

121m (400ft)

0.37–2.2 kW (0.5–3 HP)

Reactor at

Dr ve➀

15m (50ft)

➃

4.0 kW (5 HP)

Drive➀

15m (50ft)

182m (600ft)

➃

7–

–

)

Reactor at

➃

0.37–4.0 kW (0.5–5 HP)

Motor➁

➃

0.37–1.5 kW (0.5–2 HP)

Terminator

r➂

➃

2.2–4.0 kW (3–5 HP)

at Motor➂

167m (550ft)

➃

➀

A 3% reactor at the drive provides lower rise time and lower stress on the motor
cable, but may produce a poorer waveform to the motor. The reactor must have a
turn-to-turn insulation rating of 2100 volts or higher for 460V motors. Not
recommended for lightly loaded motor applications because overvoltage trips may
occur at low output frequencies.