Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control (PanelView 550) - Manual (Page 35)

Rockwell Automation Publication 7000-UM151E-EN-P - January 2013 35
Component Definition and Maintenance Chapter 3
Each MOV panel is grounded. Ensure that one MOV (see Figure 18 on page 34
for location) connects to the grounding lead.
Surge Arresters
These medium voltage drives use heavy duty distribution class surge arresters for
transient overvoltage protection in the drives with AFE rectifiers. The arresters
are certified as per ANSI/IEEE Std C62.11-1993.
The surge arresters are MOVs, with or without an air gap in series, in sealed
housing. They provide overvoltage protection similar to that of the TSN module.
They differ from the TSN in that fusing is not mandatory for the operation of
surge arresters.
There are 3 types of surge arresters depending on the voltage class of the drive:
The most severe temporary overvoltage occurs when one phase is grounded in an
ungrounded system. The full line-to-line voltage applies to the arrester in this
case. The arresters operate under this condition continuously without any
problems as indicated by their Maximum Continuous Operating Voltage
(MCOV) rating.
Three Y-connected surge arresters attach to the incoming MV lines. The neutral
point of the arresters connects to the ground bus.
Figure 19 - Surge arresters on incoming MV lines
Drive Voltage 2.4 kV 3.3 kV, 4.16 kV, 4.8 kV 6.0-6.9 kV
Arrester rating (RMS) 3 kV 6 kV 9 kV
Arrester MCOV (RMS) 2.55 5.10 7.65
U
Heavy duty
distribution
class surge
arrester
W V
Drive input power from
line terminals