Rockwell Automation 294D ArmorStart LT Distributed Motor Controller DeviceNet Version - User Manual - Manual (Page 59)

Rockwell Automation Publication 290D-UM001A-EN-P - June 2012 59
Installation and Wiring Chapter 2
In addition, if line disturbance mitigation is also necessary, the ArmorStart LT is
equipped with an EMI filter and when used with a shielded motor cable reduces
the impact of the power switching components. For CE compliant installations
refer to the recommended EMI/RFI cord grip accessory or quick disconnect
shielded motor cable. Contact your local sales representative for details.
If however, the customer specifications require input line reactors or transformers,
the recommendation is to group the ArmorStarts at the distribution panel under
one line reactor (not individual reactors or transformers). Keep in mind where
full voltage ArmorStarts are included with VFD ArmorStarts, the starting
currents of the full voltage ArmorStarts can be significant. The current must be
accounted for in the selection of the line reactor or you run the risk of nuisance
undervoltage faults of the VFD ArmorStarts while the full voltage ArmorStarts
are starting their motors.
Bulletin 294D Motor Cable
Considerations The majority of recommendations regarding drive cable address issues are caused
by the nature of the drive output. A PWM drive creates AC motor current by
sending DC voltage pulses to the motor in a specific pattern. These pulses
affect the wire insulation and can be a source of electrical noise. The rise time,
amplitude, and frequency of these pulses must be considered when choosing a
wire/cable type. The choice of cable must consider:
1. The effects of the drive output once the cable is installed
2. The need for the cable to contain noise caused by the drive output
3. The amount of cable charging current available from the drive
4. Possible voltage drop (and subsequent loss of torque)
for long wire runs
Keep the motor cable lengths less than 45 ft from the ArmorStart LT.
Unshielded Cable
Properly designed multi-conductor cable can provide superior performance
in wet applications, significantly reduce voltage stress on wire insulation and
reduce cross coupling between drives.
The use of cables without shielding is generally acceptable for installations
where electrical noise created by the drive does not interfere with the operation
of other devices such as: communications cards, photoelectric switches, weigh
scales, and others. Be certain the installation does not require shielded cable
ATTENTION: For 50°C ambients ArmorStart LT must be derated and applied
with a minimum of 800 uH to1200 uH line reactor. Failure to follow this
application requirement will result in premature product failure. Contact your
local Rockwell Automation representative for assistance.