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. 397-9189
Mfr. Part No.70PCVR-4W 400VAC
HK$1,210.68
Each
units
Phase, Voltage 400 V ac 4NO/4NC Overvoltage, Undervoltage 3 Maximum of 400 V ac - - - Neutral Loss, Phase Loss 200 ms - - -
RS Stock No. 614-9448
Mfr. Part No.84872142
BrandCrouzet
HK$763.86
Each
units
Voltage 110 → 240 V ac/dc SPDT Overvoltage, Undervoltage 1 65 → 260 V ac/dc - - - - 0.1 → 10 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. 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. 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. 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. 538-3805
Mfr. Part No.P48SMP 1-30SEC 115/230VAC
HK$774.03
Each
units
Current 115 V ac, 230 V ac SPDT - - - - - - - 1 → 30 s, 2 → 60 s - - -
RS Stock No. 819-3305
Mfr. Part No.K8AK-VW3 100-240VAC
BrandOmron
HK$980.47
Each
units
Voltage 100 → 240 V ac SPDT Overvoltage, Undervoltage 1 20 → 200 V ac/dc, 30 → 300 V ac/dc, 60 → 600 V ac/dc - - - - 0.1 → 30 s - - -
RS Stock No. 857-7662
Mfr. Part No.DPA51CM44
HK$1,397.07
Each
units
Phase 208 → 480 V ac SPDT - 3 177 → 550 V ac - - - Phase Loss, Phase Sequence - - - -
RS Stock No. 801-6218
Mfr. Part No.2866022
HK$2,088.64
Each
units
Current 24 → 240 V ac/dc DPDT - 1 - Overcurrent, Undercurrent 0A 0.1 A, 1 A, 10 A - 0.1 → 10 s - - -
RS Stock No. 463-3402
Mfr. Part No.84871030
BrandCrouzet
HK$856.02
Each
units
Current 24 V dc SPDT - 1 - Overcurrent, Undercurrent 0.1A 10A - 0.1 → 3 s - - -
RS Stock No. 145-976
Mfr. Part No.RM35JA32MW
HK$1,161.10
Each
units
Current 24 → 240 V ac/dc DPDT - - - Overcurrent, Undercurrent 0.15A 15A - 0.3 → 30 s - - -
RS Stock No. 819-3201
Mfr. Part No.K8AK-AS1 100-240VAC
BrandOmron
HK$822.25
Each
units
Current 100 → 240 V ac SPDT - 1 - Overcurrent, Undercurrent 2 500mA - - - - -
RS Stock No. 794-3935
Mfr. Part No.MA51BC
BrandGIC
HK$293.43
Each
units
Voltage 415 V ac SPDT - 3 - - - 5A - 2 s, 7 s - - -
RS Stock No. 850-5364
Mfr. Part No.LXPRC/S-4W 230V (400V)
HK$679.41
Each
units
Phase, Voltage 230 V ac SPDT Overvoltage, Undervoltage - 173 → 218 (Under) V, 242 → 288 (Over) V - - - Phase Failure, Phase Sequence 0.2 → 10 s - - -
RS Stock No. 361-1625
Mfr. Part No.45UFR 230VAC
HK$792.62
Each
units
Frequency 230 V ac DPDT - 1 - - - - - 200 ms - - 40 → 60 Hz, 50 → 70 Hz
RS Stock No. 876-4985
Mfr. Part No.1SVR730720R1400
BrandABB
HK$861.65
Each
units
Temperature 24 → 240 V ac/dc SPDT - - - - - - - <100 ms Overtemperature, Winding Temperature - -
RS Stock No. 614-9347
Mfr. Part No.84870700
BrandCrouzet
HK$794.35
Each
units
Level Control 24 → 240 V ac/dc DPDT - - 24 → 240 V ac - 10mA 5A - 0.1 → 5 s - - 50 → 60 Hz
RS Stock No. 146-238
Mfr. Part No.RM17TG20
HK$751.58
Each
units
Phase 208 → 440 V ac DPDT - 3 - - - - Phase Asymmetry, Phase Failure, Phase Sequence <100 ms - - -
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 - - - -