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. 361-1619
Mfr. Part No.45051 24/115/230VAC
HK$748.03
Each
units
Voltage 24 V ac, 115 V ac, 230 V ac SPDT Overvoltage, Undervoltage 1 Maximum of 230 V ac - - - - 0.1 → 10 s - - -
RS Stock No. 397-9202
Mfr. Part No.45PUVR-4W 400VAC
HK$809.62
Each
units
Phase, Voltage 400 V ac DPDT Undervoltage 3 Maximum of 400 V ac - - - Neutral Loss, Phase Loss 200 ms - - -
RS Stock No. 261-959
Mfr. Part No.84871122
BrandCrouzet
HK$820.61
Each
units
Current 24 → 240 V ac/dc SP-NO/NC - - - Overcurrent, Undercurrent 2A 20A - 500 ms - - -
RS Stock No. 145-960
Mfr. Part No.RM35LM33MW
HK$774.00
Each
units
- 20.4 → 264 V ac/dc - - - - - - - - - - - -
RS Stock No. 124-0193
Mfr. Part No.RM35LM33MW
HK$643.18
Each
units
Level 20.4 → 264 V ac/dc DPDT - 1 - - - - - 0.1 → 5 s - - -
RS Stock No. 614-9397
Mfr. Part No.84871130
BrandCrouzet
HK$1,034.55
Each
units
Current 24 → 240 V ac/dc DPDT - 3 - Overcurrent, Undercurrent 0.1A 10A - 0.1 → 3 s - - -
RS Stock No. 819-3254
Mfr. Part No.K8AKPH1200500VAC
BrandOmron
HK$551.58
Each
units
Phase 200 → 480 V ac DPDT - 3 - - - - Phase Loss, Phase Sequence 0.1 s - - -
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. 463-3654
Mfr. Part No.84871034
BrandCrouzet
HK$942.39
Each
units
Current 230 V ac SPDT - 1 - Overcurrent, Undercurrent 0.1mA 10A - 0.1 → 3 s - - -
RS Stock No. 850-5395
Mfr. Part No.LXCVR 230V
HK$472.65
Each
units
Phase, Voltage 230 V ac SPDT Overvoltage, Undervoltage - 173 → 218 (Under) V, 242 → 288 (Over) V - - - Single Phase 0.2 → 10 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. 775-7902
Mfr. Part No.1SVR730884R3300
BrandABB
HK$1,865.63
Each
units
Phase, Voltage 300 → 500 V ac DPDT Overvoltage, Undervoltage 3 300 → 500 V ac - - - Phase Failure, Phase Imbalance, Phase Sequence 0 s, 0.1 → 30 s - - 45 → 65 Hz
RS Stock No. 775-7974
Mfr. Part No.1SVR730840R0400
BrandABB
HK$1,748.46
Each
units
Current 24 → 240 V ac/dc DPDT - 1 - Overcurrent, Undercurrent 0.1 A, 3 mA, 10 mA 1 A, 30 mA, 100 mA - 0 s, 0.1 → 30 s - - 50 → 60 Hz
RS Stock No. 397-9145
Mfr. Part No.70POCR 400VAC
HK$1,304.22
Each
units
Current 400 V ac DPDT - 3 - Overcurrent - 5A - 0.2 → 10 s - - -
RS Stock No. 914-4654
Mfr. Part No.ICV 230Vac
BrandHiquel
HK$910.56
Each
units
Voltage 230 V ac DPDT Overvoltage, Undervoltage 1 0 → 10 (E1-M) V, 0 → 45 (E2-M) V, 0 → 450 (E3-M) V - - - - - - - -
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. 850-5411
Mfr. Part No.LBVR/A 12-24VDC
HK$503.71
Each
units
Voltage 8 → 30 V dc SPDT Undervoltage - 12 → 24 V dc - - - - 0 → 30 s - - -
RS Stock No. 775-7970
Mfr. Part No.1SVR730840R0300
BrandABB
HK$1,650.00
Each
units
Current 24 → 240 V ac/dc SPDT - 1 - Overcurrent, Undercurrent 0.3 A, 1 A, 3 A 1.5 A, 5 A, 15 A - - - - -
RS Stock No. 397-9218
Mfr. Part No.45PSR 400VAC
HK$662.85
Each
units
Phase 400 V ac SPDT - 3 - - - - Phase Loss, Phase Sequence 200 ms - - -
RS Stock No. 850-5360
Mfr. Part No.LXPRC/S 400V
HK$528.56
Each
units
Phase, Voltage 400 V ac SPDT Overvoltage, Undervoltage - 300 → 380 (Under) V, 420 → 500 (Over) V - - - Phase Failure, Phase Sequence 0.2 → 10 s - - -
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