Monitoring Relays

Monitoring relays are a type of relay that trips a circuit breaker when a fault is detected. A relay is an electrically controlled switch that is used to turn the power on or off in a circuit. 




Monitoring relays are more sophisticated than regular relays, as they have adjustable operating conditions, whereas normal relays switch according to a fixed threshold. They measure a given parameter, such as voltage or temperature, and will trip a circuit breaker when the parameter gets too high or low. 




What are monitoring relays used for?


Monitoring relays have a wide range of uses, depending largely on the factor being monitored. For example, they can protect against overcurrent if measuring current, or they can detect an abnormally low frequency if frequency is being measured.




Types of monitoring relay


The main way in which monitoring relays differ is the function that they measure. This can be a number of things, including:



  • voltage

  • current

  • temperature

  • frequency


The factor that you need to measure will decide which monitoring relay you choose.


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Description Price Monitoring Application Supply Voltage Contact Configuration Voltage Sensitivity Electrical Phase Voltage Sensing Range Current Sensitivity Minimum Current Sensed Maximum Current Sensed Phase Sensitivity Time Delay Temperature Sensitivity Temperature Sensing Range Frequency Sensing Range
RS Stock No. 518-7168
Mfr. Part No.3UG4622-1AW30
BrandSiemens
HK$1,225.47
Each
units
Current 24 → 240 V ac/dc SPDT - 1 - Overcurrent, Undercurrent 50mA 10A - 0.1 → 20 s - - -
RS Stock No. 518-7174
Mfr. Part No.3UG4615-1CR20
BrandSiemens
HK$1,616.07
Each
units
Phase, Voltage 160 → 690 V ac DPDT Overvoltage, Undervoltage 3 160 → 690 V ac - - - Phase Failure, Phase Sequence 0.1 → 20 s - - -
RS Stock No. 518-7297
Mfr. Part No.3UG4513-1BR20
BrandSiemens
HK$1,073.14
Each
units
Phase, Voltage 160 → 690 V ac DPDT Undervoltage 3 160 → 690 V ac - - - Phase Failure, Phase Imbalance, Phase Sequence 0.1 → 20 s - - -
RS Stock No. 518-7124
Mfr. Part No.3UG4621-1AW30
BrandSiemens
HK$1,149.50
Each
units
Current 24 → 240 V ac/dc SPDT - 1 - Overcurrent, Undercurrent 3mA 500mA - 0.1 → 20 s - - -
RS Stock No. 518-7275
Mfr. Part No.3UG4511-1BP20
BrandSiemens
HK$757.42
Each
units
Phase 320 → 500 V ac DPDT - 3 - - - - Phase Sequence - - - -
RS Stock No. 518-7051
Mfr. Part No.3UG4614-1BR20
BrandSiemens
HK$1,206.98
Each
units
Phase, Voltage 160 → 690 V ac DPDT Undervoltage 3 160 → 690 V ac - - - Phase Failure, Phase Imbalance, Phase Sequence 0.1 → 20 s - - -
RS Stock No. 758-6924
Mfr. Part No.3UG4512-1AR20
BrandSiemens
HK$808.47
Each
units
Phase 160 → 690 V ac SPDT - - 160 → 690 V ac - - - Phase Failure, Phase Sequence - - - -
RS Stock No. 417-9920
Mfr. Part No.3RN1022-1DW00
BrandSiemens
HK$2,429.15
Each
units
Thermistor motor protection relay 24 → 240 V ac/dc SPST - - - - - - - - Overtemperature, Undertemperature +60 → +180°C -
RS Stock No. 392-7267
Mfr. Part No.3RN1010-1CB00
BrandSiemens
HK$540.00
Each
units
Thermistor motor protection relay 24 V ac/dc SPDT - - - - - - - - Overtemperature, Undertemperature +60 → +180°C -
RS Stock No. 772-1215
Mfr. Part No.5SV8000-6KK
BrandSiemens
HK$2,065.95
Each
units
Current 230 V ac - - - - Residual 30mA 5A - 0.02 → 5 s - - -
RS Stock No. 175-2279
Mfr. Part No.3RN2010-2CA30
BrandSiemens
HK$696.35
Each
units
Thermistor motor temperature protection 24 V ac/dc SPDT Motor Voltage - - - - - - - - - -
RS Stock No. 175-2280
Mfr. Part No.3RN2010-2CW30
BrandSiemens
HK$788.26
Each
units
Thermistor motor temperature protection 240 V ac/dc SPDT Motor Voltage - 24 → 240 V ac/dc - - - - - - - -
RS Stock No. 418-5004
Mfr. Part No.3RS1010-1CK00
BrandSiemens
HK$1,280.00
Each
units
Temperature 110/230 V ac SPDT - - - - - - - - Undertemperature -50 → +50°C -
RS Stock No. 175-2295
Mfr. Part No.3RN2013-2BW30
BrandSiemens
HK$1,745.51
Each
units
Thermistor motor temperature protection 240 V ac/dc DPDT Motor Voltage - 24 → 240 V ac/dc - - - - - - - -
RS Stock No. 175-2283
Mfr. Part No.3RN2011-2BA30
BrandSiemens
HK$928.46
Each
units
Thermistor motor temperature protection 24 V ac/dc DPDT Motor Voltage - - - - - - - - - -
RS Stock No. 175-2270
Mfr. Part No.3RN2000-1AW30
BrandSiemens
HK$600.71
Each
units
Thermistor motor temperature protection 240 V ac/dc SPDT Motor Voltage - 24 → 240 V ac/dc - - - - - - - -
RS Stock No. 758-6933
Mfr. Part No.3UG4614-2BR20
BrandSiemens
HK$1,287.47
Each
units
Phase 160 → 690 V ac DPDT - - 160 → 690 V ac - - - Phase Failure, Phase Sequence 0.1 → 20 s - - -
RS Stock No. 175-2296
Mfr. Part No.3RN2013-2GW30
BrandSiemens
HK$1,829.07
Each
units
Thermistor motor temperature protection 240 V ac/dc DPDT Motor Voltage - 24 → 240 V ac/dc - - - - - - - -
RS Stock No. 175-2298
Mfr. Part No.3RN2023-2DW30
BrandSiemens
HK$2,497.56
Each
units
Thermistor motor temperature protection 240 V ac/dc CO, NO Motor Voltage - 24 → 240 V ac/dc - - - - - - - -
RS Stock No. 175-2281
Mfr. Part No.3RN2011-1BA30
BrandSiemens
HK$928.46
Each
units
Thermistor motor temperature protection 24 V ac/dc DPDT Motor Voltage - - - - - - - - - -