For thermal overload and short-circuit protection of transformers and ac motors, usually rated 50 horsepower or more
For thermal overload and short-circuit protection of transformers and ac motors, usually rated 50 horsepower or more. The BL-1 relay consists of a heater unit and an instantaneous trip unit. The operating curve of the heater unit closely duplicates the average heating curve of electrical machinery over a wide enough range that additional use of a "long-time" overcurrent relay is not required for many applications. Ambient temperature compensation in the BL-1 minimizes the effect of temperature differences between the protected apparatus location and the relay location. The BL-1 relay can be supplied with one thermal unit for single phase ac applications; or with two thermal units for polyphase ac applications.
- Long product life
- Ease of application
- Reliable protection
- High-quality design