Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive (A Frame) - ForGe Control - Manual (Page 62)

62 Rockwell Automation Publication 7000A-UM200C-EN-P - June 2014
Chapter 3 Component Definition and Maintenance
Surge Arresters Description
Heavy duty distribution class surge arresters are used 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 basically MOVs, with or without an air gap in series,
packed in sealed housing. They provide overvoltage protection similar to what the
TSN module does. They differ from the TSN in that fusing is not required for
the operation of surge arresters.
There are three types of surge arresters depending on the voltage class of the drive
as shown in the following table:
The most severe temporary overvoltage occurs when one phase is grounded in an
ungrounded system. The full line-to-line voltage is applied to the arrester in this
case. The arresters are designed to operate under this condition continuously
without any problems as shown by their Maximum Continuous Operating
Voltage (MCOV) rating.
There are three Y-connected surge arresters attached to the incoming MV lines.
The neutral point of the arresters is connected to the ground bus.
Figure 46 - Surge Arresters
Drive voltage 2.4kV 3.3kV 4.16, 4.8 kV 6.0...6.9kV
Arrester rating (RMS) 3 kV 6 kV 9 kV
Arrester MCOV (RMS) 2.55 5.10 7.65
U W V
Drive Input from Line Terminals
Heavy Duty
Distribution Class
Surge Arrester