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. 518-7203
Mfr. Part No.3RN1011-1BB00
BrandSiemens
$245.98
Each
units
Thermistor motor protection relay 24 V ac/dc DPDT - - - - - - - - Overtemperature, Undertemperature +60 → +180°C -
RS Stock No. 397-9139
Mfr. Part No.45TCR 24/230VAC
$226.98
Each
units
Temperature 24/230 V ac - - - - - - - - 200 ms - -50 → +300°C 0 → 100 °C, 0 → 50 °C, 100 → 200 °C, 200 → 300 °C, -50 → 50 °C
RS Stock No. 758-6924
Mfr. Part No.3UG4512-1AR20
BrandSiemens
$171.75
Each
units
Phase 160 → 690 V ac SPDT - - 160 → 690 V ac - - - Phase Failure, Phase Sequence - - - -
RS Stock No. 146-238
Mfr. Part No.RM17TG20
$249.52
Each
units
Phase 208 → 440 V ac DPDT - 3 - - - - Phase Asymmetry, Phase Failure, Phase Sequence <100 ms - - -
RS Stock No. 111-3108
Mfr. Part No.K8DT-VS2CD
BrandOmron
$190.01
Each
units
Voltage 24 V ac/dc SPDT Overvoltage, Undervoltage 1 1 → 10 V, 15 → 150 V, 3 → 30 V - - - - 250 ms - - -
RS Stock No. 146-143
Mfr. Part No.RM35UA12MW
$437.01
Each
units
Voltage 24 → 240 V ac/dc DPDT Overvoltage, Undervoltage - 1 → 100 V - - - - 0.3 → 30 s - - -
RS Stock No. 776-3663
Mfr. Part No.A9E16070
$434.84
Each
units
Time Delay 24 V dc, 24 → 240 V ac SPDT - - 24 → 240 V ac - - - - - - - -
RS Stock No. 850-5411
Mfr. Part No.LBVR/A 12-24VDC
$105.64
Each
units
Voltage 8 → 30 V dc SPDT Undervoltage - 12 → 24 V dc - - - - 0 → 30 s - - -
RS Stock No. 837-7496
Mfr. Part No.84870200
BrandCrouzet
$132.76
Each
units
Level Control 24 → 240 V ac/dc SPDT - - - - - - - 0.1 → 5 s - - -
RS Stock No. 397-9202
Mfr. Part No.45PUVR-4W 400VAC
$163.05
Each
units
Phase, Voltage 400 V ac DPDT Undervoltage 3 Maximum of 400 V ac - - - Neutral Loss, Phase Loss 200 ms - - -
RS Stock No. 776-3648
Mfr. Part No.A9E16065
$372.98
Each
units
Time Delay 24 V dc, 24 → 240 V ac SPDT - - 24 → 240 V ac - - - - - - - -
RS Stock No. 819-3254
Mfr. Part No.K8AKPH1200500VAC
BrandOmron
$170.59
Each
units
Phase 200 → 480 V ac DPDT - 3 - - - - Phase Loss, Phase Sequence 0.1 s - - -
RS Stock No. 123-9742
Mfr. Part No.G2PF400VS02
BrandTele
$124.04
Each
units
Phase, Voltage 230 → 400 V DPDT Self Powered 3 230 → 400 V - - - Phase Failure, Phase Sequence 350 (Tripping) ms, 500 (Start Up) ms - - -
RS Stock No. 819-3302
Mfr. Part No.K8AK-VW2 24VAC/DC
BrandOmron
$254.26
Each
units
Voltage 24 V ac/dc SPDT Overvoltage, Undervoltage 1 1 → 10 V ac/dc, 15 → 150 V ac/dc, 3 → 30 V ac/dc - - - - 0.1 → 30 s - - -
RS Stock No. 124-0182
Mfr. Part No.RM22LG11MR
$182.70
Each
units
Level 20.4 → 264 V ac/dc SPDT - 1 - - - - - <0.6 (Run-Up) s - - -
RS Stock No. 298-9416
Mfr. Part No.45175 230VAC
$173.26
Each
units
Speed 230 V ac SPDT - - - - - - - 0.5 → 30 min, 0.5 → 30 s - - -
RS Stock No. 857-7426
Mfr. Part No.DPC01DM48
$731.47
Each
units
Phase, Voltage 380 → 480 V ac SPDT Overvoltage, Undervoltage 3, 3+N 323 → 550 V ac - - - Asymmetry, Phase Loss, Phase Sequence, Tolerance 1 s, 6 s - - 50 → 60 Hz
RS Stock No. 819-3210
Mfr. Part No.K8AK-AS3 100-240VAC
BrandOmron
$251.08
Each
units
Current 100 → 240 V ac SPDT - 1 - Overcurrent, Undercurrent 10A 200A - - - - -
RS Stock No. 876-5799
Mfr. Part No.CM-TCS.23P
BrandABB
$400.98
Each
units
Temperature 24 V ac/dc SPDT - 3 - - - - - 20 ms Overtemperature, Temperature Window Monitoring, Undertemperature 0 → +200°C 45 → 65 Hz
RS Stock No. 819-3214
Mfr. Part No.K8AK-AS3 24VAC/DC
BrandOmron
$193.51
Each
units
Current 24 V ac/dc SPDT - 1 - Overcurrent, Undercurrent 10A 200A - - - - -
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