ABB TF42-1.7 Thermal Overload Relay, 1.2 - 1.7 A, Class 10, 3-Pole, 690 V AC/DC

Motor burnout from sustained overloads is a constant threat in industrial environments. The ABB TF42-1.7 thermal overload relay provides dependable protection for three-phase motors by interrupting the circuit when current exceeds safe levels. With a setting range of 1.2 to 1.7 A and Class 10 tripping characteristics, it responds quickly to overload conditions while allowing normal motor starting. This relay is engineered for direct mounting on ABB AF series contactors, simplifying installation and ensuring reliable coordination.

Who is it for

This relay is intended for panel builders, maintenance technicians, and OEMs who need compact, reliable motor protection in applications such as conveyors, pumps, fans, and machine tools. It suits both new installations and retrofits where space is limited and dependable overload protection is required.

Main features

• Adjustable current setting from 1.2 A to 1.7 A for precise motor matching.
• Class 10 tripping curve protects motors during normal startup while preventing damage from prolonged overloads.
• Three-pole design with differential phase loss protection.
• Manual and automatic reset modes for flexible operation.
• Direct mounting on ABB AF09...AF38 contactors; also suitable for stand-alone installation.
• Auxiliary contacts: 1 NO + 1 NC for status signaling and control interlocking.
• Wide operating temperature range: -25 °C to +60 °C.
• Complies with international standards IEC/EN 60947-4-1, UL, and CSA.

Specifications

• Current setting range: 1.2 - 1.7 A
• Tripping class: Class 10
• Number of poles: 3
• Rated operational voltage: 690 V AC / 600 V DC
• Rated insulation voltage: 690 V
• Rated impulse withstand voltage: 6 kV
• Auxiliary contacts: 1 NO + 1 NC
• Reset type: Manual and automatic
• Mounting: Direct contactor mounting / stand-alone
• Compatible contactors: ABB AF09, AF12, AF16, AF26, AF30, AF38
• Operating temperature: -25 to +60 °C
• Storage temperature: -40 to +70 °C
• Degree of protection: IP20
• Power loss per pole: 0.5 W
• Standards: IEC/EN 60947-4-1, UL 60947-4-1, CSA C22.2 No. 60947-4-1

Tips

Set the current adjustment dial to the motor's full load current as indicated on its nameplate. For motors with high starting currents, ensure the tripping class is compatible with the startup time. Use the manual reset mode when a fault requires operator intervention before restart. Regularly check the relay for dust accumulation and ensure proper ventilation to maintain accurate thermal response.