Rockwell Automation Publication 7000-UM202H-EN-P - November 2023 39
Chapter 2 Power Component Definition and Maintenance
Surge Arresters
The drive uses 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 three 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 rating.
Three Y-connected surge arresters attach to the incoming MV lines. The
neutral point of the arresters connects to the ground bus.
Figure 31 - Surge Arresters on Incoming MV Lines
Operation
Arrester operation without a gap is the same as that of MOVs in the TSN.
Depending on design, the arrester may also have a gap. Both gapped and un-
gapped arresters provide adequate overvoltage protection.
The arresters can withstand most commonly-seen bus transients within their
capability. If there is a harmonic filter on the MV bus connected to the drive,
the filter must satisfy relevant international or local standards, such as IEEE
Std 1531— Clause 6.4, to avoid high inrush currents.
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
Drive Input from Line Terminals
Heavy-duty
Distribution Class
Surge Arrestor
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