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.
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.
Overload Relays on-line now
- 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 the thermal overload relays we have available to buy on-line.
- ABB TF AF Range Thermal Overload Relays
- ABB T16 AS Range Mini Thermal Overload Relays
- ABB Thermal Overload Relays TA Range