Crompton 252-PMMU-STBX-DG Protector Trip Relay -Thermiston Trip MANUAL RESET

Thermistor Trip Many motors, Transformer s and generators are fitted with positive temperature co-efficient thermistor temperature sensors. The addition of a thermistor trip relay will provide full protection against sustained overload, single phasing, locked rotor, blocked ventilation and high ambient temperature. Thermistor trip relays continuously monitor the working temperature inside electrical equipment. When the temperature exceeds a safe limit, the relay can be used to shut down equipment until it regains a safe operating temperature.

Operation Thermistors are simple low cost temperature sensors. The thermistor trip protector operates by de-energising a relay when the thermistors detect a critical temperature condition. An illuminated green LED indicates when the temperature is within normal working limits. Any number of thermistors may be used in series connection providing the resistance at normal working temperature is less than 1500 ohms. There are no user adjustments on this relay. Model 252-PMT will automatically reset when temperature returns to normal. For Model 252-PMM, fitting a link between terminals R1 and R2 will latch the product in its tripped state when an over-temperature condition is detected. The relay can be reset by pressing the front panel reset switch, opening the R1œR2 link, or interrupting the auxiliary supply.