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. 518-7297
Mfr. Part No.3UG4513-1BR20
BrandSiemens
$380.73
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. 857-7696
Mfr. Part No.DPB01CM48
$402.37
Each
units
Phase, Voltage 380 → 480 V ac SPDT Overvoltage, Undervoltage 3, 3+N 323 → 550 V ac - - - Phase Loss, Phase Sequence 1 s, 6 s - - -
RS Stock No. 124-0193
Mfr. Part No.RM35LM33MW
$83.81
Each
units
Level 20.4 → 264 V ac/dc DPDT - 1 - - - - - 0.1 → 5 s - - -
RS Stock No. 145-960
Mfr. Part No.RM35LM33MW
$228.96
Each
units
- 20.4 → 264 V ac/dc - - - - - - - - - - - -
RS Stock No. 146-480
Mfr. Part No.RM35TF30
$431.46
Each
units
Phase, Voltage 220 → 480 V ac DPDT Overvoltage, Undervoltage 3 194 → 528 V ac - - - Phase Asymmetry, Phase Failure, Phase Sequence 0.1 → 10 s - - -
RS Stock No. 857-7662
Mfr. Part No.DPA51CM44
$307.43
Each
units
Phase 208 → 480 V ac SPDT - 3 177 → 550 V ac - - - Phase Loss, Phase Sequence - - - -
RS Stock No. 146-238
Mfr. Part No.RM17TG20
$193.80
Each
units
Phase 208 → 440 V ac DPDT - 3 - - - - Phase Asymmetry, Phase Failure, Phase Sequence <100 ms - - -
RS Stock No. 261-959
Mfr. Part No.84871122
BrandCrouzet
$179.08
Each
units
Current 24 → 240 V ac/dc SP-NO/NC - - - Overcurrent, Undercurrent 2A 20A - 500 ms - - -
RS Stock No. 850-5411
Mfr. Part No.LBVR/A 12-24VDC
$96.04
Each
units
Voltage 8 → 30 V dc SPDT Undervoltage - 12 → 24 V dc - - - - 0 → 30 s - - -
RS Stock No. 850-5405
Mfr. Part No.LMCVR-500V 24-230VAC/DC
$199.97
Each
units
Voltage 24 → 230 V ac/dc SPDT Overvoltage, Undervoltage - 2 → 20 V, 5 → 50 V, 10 → 100 V, 20 → 200 V, 50 → 500 V - - - - 0.1 → 30 s - - -
RS Stock No. 775-7889
Mfr. Part No.1SVR730784R2300
BrandABB
$252.81
Each
units
Phase, Voltage 380 V ac DPDT - 3 342 → 418 V ac - - - Phase Failure, Phase Sequence 0 s, 0.1 → 30 s - - 45 → 65 Hz
RS Stock No. 857-7075
Mfr. Part No.DIA53S72420A
$182.79
Each
units
Current - SPST - 1 - Overcurrent - - - <300 ms - - -
RS Stock No. 806-5910
Mfr. Part No.1SVR730660R0100
BrandABB
$492.80
Each
units
Insulation 24 → 240 V ac/dc SPDT - - 0 → 250 V ac, 0 → 300 V dc - - - - - - - -
RS Stock No. 146-597
Mfr. Part No.RM17TU00
$204.00
Each
units
Phase, Voltage 208 → 480 V ac SPDT Undervoltage 3 183 → 528 V ac - - - Phase Failure, Phase Sequence 0.1 → 10 s - - -
RS Stock No. 518-7174
Mfr. Part No.3UG4615-1CR20
BrandSiemens
$297.01
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. 392-7267
Mfr. Part No.3RN1010-1CB00
BrandSiemens
$211.10
Each
units
Thermistor motor protection relay 24 V ac/dc SPDT - - - - - - - - Overtemperature, Undertemperature +60 → +180°C -
RS Stock No. 629-386
Mfr. Part No.M3PPI 300-500vAC
$90.26
Each
units
Phase 300 → 500 V ac - - 3 - - - - Phase Loss, Phase Sequence - - - -
RS Stock No. 261-909
Mfr. Part No.84873021
BrandCrouzet
$148.41
Each
units
Phase 208 → 440 V ac DPDT - 3 - - - - Phase Failure, Phase Sequence 500 ms - - -
RS Stock No. 859-3027
Mfr. Part No.DUA52C724
$211.31
Each
units
Voltage 12 → 24 V dc SPDT Undervoltage - 8 → 28 V dc - - - - <200 ms - - -
RS Stock No. 776-3648
Mfr. Part No.A9E16065
$339.07
Each
units
Time Delay 24 V dc, 24 → 240 V ac SPDT - - 24 → 240 V ac - - - - - - - -
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