A thermal overload relay senses overload current through the thermal bending of bimetal strips: the higher the current, the faster the strips bend, and when they reach the trip point the contact opens, cutting the contactor coil and stopping the motor. The Fuji Electric TR series uses trip class 10A for standard overload protection of general induction motors. The two models cover 9–13 A and 24–36 A and combine directly with Fuji SC series contactors.
The current adjustment dial can be set steplessly within the range, so it can match different motors without changing parts.
Model comparison
| Model | Current range | Motor | Trip class | Matching contactor | Size (W × H × D) | Weight |
|---|---|---|---|---|---|---|
| TR-N2/3 (9–13 A) | 9–13 A | 5.5 kW at 400 V | Class 10A | SC-51 / SC-N1 | 45 × 75 × 95 mm | About 0.65 kg |
| TR-2N/3 (24–36 A) (discontinued) | 24–36 A | 15 kW at 400 V | Class 10A | SC-N2 / SC-N2S | 60 × 85 × 115 mm | About 1.2 kg |
About trip class 10A
IEC 60947-4-1 defines the trip class of overload relays. Class 10A: starting cold at 7.2 × the current setting, the relay trips in more than 2 s and up to 10 s (IEC 60947-4-1). It suits direct-on-line starting of general induction motors. If the motor load has high inertia and the starting current lasts longer, you may need a Class 20 or 30 relay.
- Manual reset: after tripping, press the reset button to re-energize, preventing an automatic restart before the cause is found.
- Dial current setting: adjustable continuously within the rated range, so motors of different power can be matched without changing the relay.
- Phase-loss protection: 3-pole design; if any phase is lost, the three bimetal strips go out of balance and trigger a trip.
How to request a quote: please send (1) the model and current range; (2) the matching contactor; (3) the quantity; (4) how urgent it is.
Trademarks: Fuji Electric and the model names on this page are trademarks or model names of their owner, used here only to identify the products. JIAHON is not the authorized distributor of Fuji Electric in Taiwan.
Request a quote
Send the model, current range, quantity and urgency. Request a quote →