Motor branch circuit analysis, Motor branch circuit analysis -4 – Rockwell Automation 160 SSC Series C FRN 7.xx User Manual

Page 16

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2-4

Installation and Wiring

Motor Branch Circuit Analysis

Short circuit and overload protection are requirements of any motor branch circuit.
Input power conditioning, CE conformance, reflective wave, capacitive current
coupling, and motor cable type are important considerations of drive applications.

Branch Circuit Configuration

Figure 2.3

Branch Circuit Protective Devices

A motor branch circuit requires protection against excessive current. This
protection can be provided by a fuse, circuit breaker, or manual motor starter.
See Table 2.B for a detailed list of these options.

Input Power Conditioning

Certain conditions may exist that could damage a drive in the branch circuit.
See Table 2.C for an explanation of problems and solutions.

CE Conformance

See Appendix C for information on CE Conformance.

Motor Cable Types

See Table 2.D for recommended cable types.

Reflected Wave Protection

The use of a drive may result in increased peak-to-peak voltage at the motor.
See Table 2.E for an explanation of motor insulation limitations versus cable
lengths.

Capacitive Current Coupling

High speed voltage switching causes AC coupling from motor cables to ground
terminal/protective earth. See Table 2.F for cable length recommendations.

Overload Protection

All motor branch circuits require overload protection. The Bulletin 160 Drive is
UL listed to provide protection (IEC Class 10 overload) without an overload
relay. Separate overload relays are required in multi-motor applications or if the
drive kW (HP) rating is more than three times larger than the motor kW (HP)
rating.

Branch Circuit Protective Devices – See Table 2.B

Input Power Conditioning – See Table 2.C

160 SSC™

Motor Cable Types – See Table 2.D

Reflected Wave Protection – See Table 2.E

Overload Protection

CE Conformance – See Appendix C

Capacitive Current Coupling – See Table 2.F

Motor

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