ABB TF42 Thermal Overload Relays

Thermal Overload Relay Applications

• Temperature compensation from -25  +60 °C
• Adjustable current setting for overload protection
• Automatic or manual reset selectable
• Suitable for three- and single-phase application
• Trip-free mechanism
• Status indication
• STOP and TEST function
• Direct mounting onto block contactors
• Sealable operating elements

Description

• 45mm width
• Suitable for contactor AF09 … AF38
• Sealable operating elements

Application / internal function

The thermal overload relays are three pole relays with bimetal tripping elements (1 per pole). The motor current flows through the bimetal tripping elements and heats them directly and indirectly. In case of an overload (over current), the bimetal elements become bent as a result of the heating. This leads to a release of the relay and a change of the contacts switching position (95-96 / 97-98). The contact 95-96 is used to control the load contactor.

The overload relays have a setting scale in Amperes, which allows the direct adjusting of the relay without any additional calculation. In compliance with international and national standards, the setting current is the rated current of the motor and not the tripping current (no tripping at 1.05 x I, tripping at 1.2 x I; I = setting current). The relays are constructed in way that they protect themselves in the event of an overload. The overload relay has to be protected against short-circuit. The appropriate short-circuit protection devices are shown in the table.

Ordering Details

Technical Data