TR Series Circuit Breakers Altech TR Series Circuit Breakers are UL1077-recognized supplementary protectors that offer a 0.1A to 16A current rating range. These circuit breakers feature a thermal ‘TO’ trip-free method of tripping. The TR circuit breakers operate at +60°C maximum ambient temperature. These circuit breakers offer a 1W to 2W power loss range. The TR circuit breakers are ideal to protect control transformers, uninterruptible power supplies (UPS), power strips, and solenoids.