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$1,406.33
Each
units
Current - SPDT - 1 - Overcurrent, Undercurrent 50mA 10A - 0.1 → 20s - - -
RS Stock No. 518-7174
Mfr. Part No.3UG4615-1CR20
BrandSiemens
HK$1,607.43
Each
units
Phase, Voltage - DPDT Overvoltage, Undervoltage 3 160 → 690V ac - - - Phase Failure, Phase Sequence 0.1 → 20s - - -
RS Stock No. 518-7297
Mfr. Part No.3UG4513-1BR20
BrandSiemens
HK$1,618.91
Each
units
Phase, Voltage - DPDT Undervoltage 3 160 → 690V ac - - - Phase Failure, Phase Imbalance, Phase Sequence 0.1 → 20s - - -
RS Stock No. 518-7275
Mfr. Part No.3UG4511-1BP20
BrandSiemens
HK$843.90
Each
units
Phase - DPDT - 3 - - - - Phase Sequence - - - -
RS Stock No. 518-7124
Mfr. Part No.3UG4621-1AW30
BrandSiemens
HK$1,783.33
Each
units
Current - SPDT - 1 - Overcurrent, Undercurrent 3mA 500mA - 0.1 → 20s - - -
RS Stock No. 392-7267
Mfr. Part No.3RN1010-1CB00
BrandSiemens
HK$1,018.72
Each
units
Thermistor motor protection relay - SPDT - - - - - - - - Overtemperature, Undertemperature +60 → +180°C -
RS Stock No. 758-6924
Mfr. Part No.3UG4512-1AR20
BrandSiemens
HK$1,172.00
Each
units
Phase - SPDT - - 160 → 690V ac - - - Phase Failure, Phase Sequence - - - -
RS Stock No. 518-7051
Mfr. Part No.3UG4614-1BR20
BrandSiemens
HK$1,740.31
Each
units
Phase, Voltage - DPDT Undervoltage 3 160 → 690V ac - - - Phase Failure, Phase Imbalance, Phase Sequence 0.1 → 20s - - -
RS Stock No. 758-6946
Mfr. Part No.3UG4633-1AL30
BrandSiemens
HK$1,083.12
Each
units
Voltage - SPDT Overvoltage, Undervoltage - 17 → 275V ac/dc - - - - 0.1 → 20s - - -
RS Stock No. 758-6920
Mfr. Part No.3UG4511-1AN20
BrandSiemens
HK$1,071.07
Each
units
Phase - SPDT - - 160 → 260V ac - - - Phase Sequence - - - -
New
RS Stock No. 211-0137
Mfr. Part No.3RR2243-1FA30
BrandSiemens
HK$3,222.88
Each
units
Current - SPDT - 3 - - - - - - - - -
RS Stock No. 203-3985
Mfr. Part No.3UG4581-1AW30
BrandSiemens
HK$2,814.65
Each
units
Voltage - SPNO - 3 - - - - - - - - -
RS Stock No. 758-6930
Mfr. Part No.3UG4622-2AW30
BrandSiemens
HK$1,890.76
Each
units
Current - SPDT - - - Overcurrent, Undercurrent 50mA 15A - 0.1 → 20s - - -
RS Stock No. 175-2292
Mfr. Part No.3RN2013-1BW30
BrandSiemens
HK$2,159.33
Each
units
Thermistor motor temperature protection - DPDT Motor Voltage - 24 → 240V ac/dc - - - - - - - -
RS Stock No. 203-3993
Mfr. Part No.3UG4625-1CW30
BrandSiemens
HK$2,512.50
Each
units
Current - DPDT - 3 - - - - - - - - -
New
RS Stock No. 213-1301
Mfr. Part No.3UG4511-2BP20
BrandSiemens
HK$1,245.87
Each
units
Phase - DPDT Overvoltage 3 - - - - - - - - -
RS Stock No. 463-5543
Mfr. Part No.3RS1101-1CK30
BrandSiemens
HK$1,772.59
Each
units
Temperature - SPDT - - - - - - - - Overtemperature 0 → +600°C -
RS Stock No. 175-2272
Mfr. Part No.3RN2000-2AW30
BrandSiemens
HK$740.19
Each
units
- - SPDT Motor Voltage - 24 → 240V ac/dc - - - - - - - -
New
RS Stock No. 213-1223
Mfr. Part No.3RR2242-1FA30
BrandSiemens
HK$2,387.92
Each
units
Current - SPDT - 3 - - - - - - - - -
New
RS Stock No. 211-3715
Mfr. Part No.3UG4501-2AW30
BrandSiemens
HK$1,235.49
Each
units
Resistance - - - - - - - - - - - - -