Re-Closing - Eaton ZE serie Handbuch

1.3.5 Re-closing

S
97 95
98 96
Normal operation 3-phase overload
(no fault)
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
￫
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.
Figure 4: Wiring of the overload relay for the protection of AC or DC motors (bimetallic releases
wired in series)
(￫ section 5.2, "Auslösekennlinien/Tripping characteristics ZE/XTOM",
page 42)
After tripping, the bimetallic releases must first cool down before the
overload relay can be reset. Manual and automatic reset can be selected by
means of a selector switch (￫ section 4.1.1, "Reset", page 38).
In auto mode, the contacts automatically fall back after the bimetallic
releases have cooled down, whereas in manual mode the tripping must be
acknowledged locally on the ZE/XTOM overload relay.
DANGER

For explosion protection, it is only permissible to reset/switch
on the motor protection relay manually, after the bimetallic
release of ZE/XTOM has cooled down, or automatically via a
control interlock circuit for the motor or electrical machinery.
Resets may be carried out at the installation or by trained
personnel in the control room.
ZE/XTOM 11/17 MN03407003Z-DE/EN www.eaton.com
1 ZE/XTOM overload relays
97 95 97 95
98 96 98 96
Failure of one phase
(two-phase load)
1.3 Description of device
29