Rockwell Automation 1336 3-20HP FRN 1.01-3.01 - Manual (Page 29)

Specifications
Chapter 4
4-2
Input Power Conditioning General
Typically the 1336 is suitable for direct connection to a correct voltage,
three phase, AC power line. There are however certain power line
conditions which may introduce the possibility of drive input power
component malfunction. To reduce the possibility of these malfunctions, a
line reactor or isolation type transformer may be required.
The basic rules for determining if a line reactor or isolation type
transformer is required are as follows:
1. If the AC line supplying the drive has power factor correction capacitors
connected, an AC line reactor or isolation type transformer must be
connected between the capacitor bank and the input to the drive.
2. If the AC line frequently experiences transient power interruptions or
significant voltage spikes, an AC line reactor or isolation type
transformer should be used.
Ungrounded Distribution Systems
All 1336 drives are equipped with an MOV (metal oxide varistor) that
provides voltage surge protection and phase-to-phase plus phase-to-ground
protection which is designed to meet IEEE 587. The MOV circuit is
designed for surge suppression only (transient line protection), not
continuous operation.
With ungrounded distribution systems, the phase-to-ground connection of
the MOV could become a continuous current path to ground. MOV
line-to-line and line-to-ground voltages should not exceed the values listed
below. Exceeding these MOV ratings may cause physical damage to the
MOV.
Line-to-Line MOV Rating
Energy Rating = 320 Joules
Turn On Voltage = 850-1000 volts
Line-to-Ground MOV Rating
Energy Rating = 380 Joules
Turn On Voltage = 1500 volts
4 3 2 1
GND
MOV1
220 Joules
160 Joules
160 Joules
160 Joules