Monitoring Relays

Monitoring relays are specialized control devices designed to continuously monitor critical electrical parameters and protect equipment from abnormal operating conditions. Commonly used in industrial and commercial environments, these relays help ensure system reliability by detecting issues such as voltage fluctuations, phase loss, current overloads, and frequency deviations before damage occurs.

RSP Supply offers a wide selection of monitoring relays, including control relays, level control relays, and frequency control relays. Voltage monitoring relays protect equipment from overvoltage and undervoltage conditions by ensuring electrical systems remain within acceptable limits. Current monitoring relays measure load current and trigger alarms or control actions when preset thresholds are exceeded, making them especially useful in motor protection and automation applications.

Many monitoring relays also provide advanced functions such as phase sequence monitoring, asymmetry detection, temperature monitoring, and power factor measurement. Adjustable settings for thresholds and time delays allow these relays to be tailored to specific application requirements. By providing real-time feedback and fault detection, monitoring relays help reduce downtime, improve system safety, and maintain consistent operational performance.

Found 157 items
Normally In Stock
Littelfuse PLM9805 Voltage Monitoring - 400-480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$222.37
$185.31
Normally In Stock
Littelfuse 460-400HZ 3-Phase Vm/ 190-480v/ 400hz/ A
Free U.S Ground shipping
$187.33
$156.11
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Littelfuse 460-B 3-Phase Volt Mon/ 190-480v/Ad
Free U.S Ground shipping
$175.28
$146.07
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Littelfuse TVM480A45S5S Voltage Monitoring - 480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$187.51
$156.26
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Littelfuse 460-MR 3-Phase Vm/ 190-480v/ Adj Vub
Free U.S Ground shipping
$232.08
$193.40
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Littelfuse 50R400 Voltage Monitoring - 380-480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$320.86
$267.38
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Phoenix Contact 2866064 Monitoring relay EMD-FL-3V-400
Free U.S Ground shipping
$358.42
$298.68
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Schneider Electric RM17UAS15 voltage control relay RM17-U - range 65..260 V AC
Free U.S Ground shipping
$195.34
$162.78
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Littelfuse 35040026 Voltage Monitoring - 380-480 Volt, Double Throw, Double Pole
Free U.S Ground shipping
$373.62
$311.35
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Schneider Electric RM22UA23MR Overvoltage control relay 15V…500Vac/dc, 2 C/O
Free U.S Ground shipping
$228.40
$190.33
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Eaton D65VMLS480C Monitoring Relay
Free U.S Ground shipping
$975.22
$812.68
Normally In Stock
Littelfuse PLS240A Voltage Monitoring - 175-255 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$152.59
$127.16
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Littelfuse PLS480A Voltage Monitoring - 380-500 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$152.59
$127.16
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Littelfuse 202 Voltage Monitoring - 190-480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$153.44
$127.87
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Littelfuse 455 Voltage Monitoring - 190-480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$325.80
$271.50
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Littelfuse 460 3-Phase Volt Mon/ 190-480v/ Ad
Free U.S Ground shipping
$183.62
$153.02
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Littelfuse 601 3-Phase Voltage Monitor W/ Dis
Free U.S Ground shipping
$581.21
$484.34
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Littelfuse 102600 Voltage Monitoring - 475-600 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$243.96
$203.30
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Littelfuse 250600 Voltage Monitoring - 500-600 Volt, Double Throw, Double Pole
Free U.S Ground shipping
$302.28
$251.90
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Littelfuse 350200 Voltage Monitoring - 190-240 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$373.62
$311.35
Normally In Stock
Littelfuse 350400 Voltage Monitoring - 380-480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$373.62
$311.35
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Littelfuse 350600 Voltage Monitoring - 475-600 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$373.62
$311.35
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Littelfuse 355200 Voltage Monitoring - 190-240 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$459.01
$382.51
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Littelfuse 355400 Voltage Monitoring - 380-480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$459.01
$382.51
Normally In Stock
Littelfuse 355600 Voltage Monitoring - 475-600 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$459.01
$382.51
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Littelfuse 455575 Voltage Monitoring - 475-600 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$325.80
$271.50
Normally In Stock
Littelfuse 601575 3-Phase Voltage Monitor W/ Dis
Free U.S Ground shipping
$581.21
$484.34
Normally In Stock
Littelfuse 3502002 Voltage Monitoring - 190-240 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$373.62
$311.35
Normally In Stock
Littelfuse 3504002 Voltage Monitoring - 380-480 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$373.62
$311.35
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Littelfuse 3506002 Voltage Monitoring - 475-600 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$373.62
$311.35
Normally In Stock
Littelfuse 3554005 Voltage Monitoring - 380-480 Volt, Double Throw, Double Pole
Free U.S Ground shipping
$459.01
$382.51
Normally In Stock
Littelfuse 35020026 Voltage Monitoring - 190-240 Volt, Double Throw, Double Pole
Free U.S Ground shipping
$373.62
$311.35
Normally In Stock
Littelfuse 35020028 Voltage Monitoring - 190-240 Volt, Double Throw, Double Pole
Free U.S Ground shipping
$388.12
$323.43
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Littelfuse 35020029 Voltage Monitoring - 190-240 Volt, Double Throw, Single Pole
Free U.S Ground shipping
$398.04
$331.70
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Littelfuse 35040025 Voltage Monitoring - 380-480 Volt, Double Throw, Double Pole
Free U.S Ground shipping
$443.56
$369.63
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Eaton D65VMLS600C Monitoring Relay
Free U.S Ground shipping
$573.35
$477.79
Normally In Stock
Littelfuse DLMHBRAAA 3 Phase Voltage Monitor
Free U.S Ground shipping
$403.79
$336.49
Normally In Stock
Littelfuse DLMUBLAAA 3 Phase Voltage Monitor
Free U.S Ground shipping
$403.79
$336.49
Normally In Stock
Littelfuse DLMUBNAAN 3 Phase Voltage Monitor
Free U.S Ground shipping
$403.79
$336.49
Normally In Stock
Littelfuse DLMUBRAAA 3 Phase Voltage Monitor
Free U.S Ground shipping
$403.79
$336.49

FAQs

Q: What is a monitoring relay?
A monitoring relay is a device used to supervise electrical parameters such as voltage, current, phase condition, frequency, or level, and initiate control actions when abnormal conditions are detected.

Q: Can monitoring relays monitor phase voltage?
Yes, many monitoring relays are designed to monitor individual phase voltages in three-phase systems to detect phase loss, imbalance, or incorrect phase sequence.

Q: What is a voltage monitoring relay used for?
Voltage monitoring relays protect electrical equipment by detecting overvoltage or undervoltage conditions and disconnecting or signaling when voltage falls outside preset limits.

Q: Where are current monitoring relays commonly used?
Current monitoring relays are frequently used in motor control and power distribution systems to detect overloads, underloads, or abnormal current conditions.

Q: What is the difference between a relay and a contactor?
Relays are typically used for lower current and voltage applications and control signaling, while contactors are designed to switch higher power loads.

Why Buy Monitoring Relays from RSP Supply

RSP Supply offers a comprehensive range of monitoring relays to support reliable electrical system protection and control. Our selection includes voltage, current, level, and frequency monitoring solutions from trusted manufacturers, suitable for a wide variety of industrial and commercial applications. Customers rely on RSP Supply for dependable components, knowledgeable technical support, and products designed to maintain system integrity and long-term performance.