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ABB Thermal Overload Relays
Thermal overload relays are used in connection with contactors A,
AF, AE, TAE, BC and TBC to protect motors with a rated operating
voltages up to 690 V a.c. and 800 V d.c.
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The thermal overload relays are three-pole relays
They have bimetallic releases (1 per phase) through which the motor current
flows and are indirectly heated.
The bimetallic releases bend subject to the influence of heating and this
results in tripping of the relay.The auxiliary contacts change their switch
position.
The relays feature a setting scale in Amperes. In compliance with
international and national standards, the setting current is the rated
motor current and not the tripping current (no tripping at 1.05 x I setting
current, tripping at 1.2 x I setting current ).
All relays feature:
- Trip-free mechanism: Tripping in the event of a fault is not
prevented even if the Reset button is pressed.
- Temperature compensation
- Phase failure protection in accordance with IEC 60947-4-1:
This device shortens the tripping times in the event of phase failure
and thus improves the motor protection within the limits of the setting
range.
- Tripping category: 10 A, in the case of thermal overload
relays TA ... DU 30, in the case of thermal overload relays TA ... SU.
- Reset and test functions
Auxiliary contacts
The relays feature two integrated auxiliary contacts
one NC contact, marked by 95 - 96
one NO contact, marked by 97 - 98
The two contacts are electrically isolated and are thus suitable for use in
two different circuits (control circuit and signalling circuit).
Click to view a selection of
Thermal Overload Relays we have available to buy on-line. |
