Motor-protective system ZEV
8
11/01 AWB2300-1433GB
Unit description Current monitoring sensors
The ZEV series of electronic motor-protective relays belongs
to the family of current-sensing protective devices, same as
the motor-protective relays operating on a bimetallic release
principle.
The ZEV monitors the motor current by means of separate
sensors, which cover the current range from 1 to 820 A.
Table 1: Current sensor operating ranges
Setting of the tripping CLASS
The system is suitable for standard and heavy startup
operation. The tripping characteristics are selected by means
of the CLASS settings. These are:
• CLASS 5 = for easy starting conditions,
• CLASS 10 = for standard starting conditions,
• CLASS 15 to CLASS 40 = for heavy to severe starting
conditions.
The switchgear is designed for standard and overload
operation of the CLASS 10. To avoid thermal overload of
switchgear under severe starting conditions, the rated
operational current I
e CLASS
of the switchgear must be
reduced according to the CLASS setting on the ZEV. The
rated operational current I
e CLASS
can be calculated based on
the reducing factors listed in Table 2 , Page 9.
Current sensor Current range I
II
I
A
ZEV-XSW-25 1 to 25
ZEV-XSW-65 3 to 65
ZEV-XSW-145 10 to 145
ZEV-XSW-820 40 to 820
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