Description of device
31
09/15 MN03407003Z-DE/EN
If the path of action of one of the bimetallic releases is
reduced due to a phase loss, the differential bridge is
retarded and the distance is converted into an additional
tripping distance, which leads to an early tripping.
Figure 3:
Function of the phase failure sensitivity by means of
tripping and differential bridge
a
Trip bridge
b
Differential bridge
c
Differential travel
s = Tripping distance
Figure 4:
Wiring of the overload relay for the protection of AC
or DC motors (bimetallic releases wired in series)
(
chapter "Auslösekennlinien/ Tripping characteristics
Normal operation
(no fault)
3-phase overload
Failure of one phase
(two-phase load)
97
S
95
98 96
97 95
98 96
97 95
98 96
햲
햳
햴
h
If the ZE/XTOM motor overload relay is to be used for
monitoring an AC or DC motor, the current must flow
through all three current paths in order to avoid early
tripping.