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This CR Magnetics current sensing relay has an internal transformer, requires a supply voltage of 120VAC, and is used for monitoring electrical current in power supply applications. This current sensing relay has a window for routing the current-carrying wire and a calibrated dial for setting the trip point. An adjustable delay-on timer provides stability. When current levels rise above the adjusted set point, the relay is tripped and starts the timer. Once the timer cycles, the relay is energized and turns the output to full on. It has an internal transformer for scaling the current up or down and a voltage reference circuit that provides a repeatable trip point. This current sensing relay has an LED indicator that alerts the user when the relay is tripped and is suitable for monitoring electric heater elements, sensing motor over/under loads, detecting lamp burn-out and indicating phase-loss.
Specifications
Contact form1 Form C (SPDT)Contact materialSilver-cadmium oxideSupply voltage120VACPower-on delay100 ms. maximumInput supply power80 mA normal; 100 mA maximumRated output20 amps maximumMaximum sensed currentContinuous 200% full scaleHysteresis5% maximumMechanical life10 million operations at normal rated loadElectrical life100,000 operations at normal rated loadInitial contact resistance50 milliohms maximum at 500 mA, 12VDCFrequency (at 60 Hz)50 to 400 HzOperating temperature-30 to +60 degrees CStorage temperature-55 to +85 degrees CTerminals3 1/4" male QCWeight0.05 lb.Standards metUL (Underwriter's Laboratories)RoHS (Restriction on Hazardous Substances)
Relay switches (also called an electrical relay or an electrical relay switch) use a small amount of power to control a larger source of power connected to electrical devices such as car motors, computers, and lighting installations. A basic relay switch has a control circuit with an electromagnetic coil and a load circuit with contacts and a lever. When current flows into the relay switch, it moves through the coil and a magnetic field is created, which causes the lever in the load circuit to move between contacts, either turning the device on or off. In a normally open (NO) relay switch, when power is supplied to the relay, the load circuit is closed and the power source connected to the relay is turned on. In a normally closed (NC) relay switch, when power is supplied to the relay, the load circuit is open and the power source connected to the relay is turned off. In other types of relay switches, non-moving parts such as transistors or semiconductors can be used as the control circuit to operate the switching mechanism. Relay switches can be controlled with an external switch, such as a light switch, or they can be connected to an automatically switched power source, such as a car ignition. One relay can operate multiple switches, and multiple relays can be operated with a single switch, with each relay operating independently from the other relays in the system.
CR Magnetics manufactures electrical sensors, indicators, and displays. The company, founded in 2004, is headquartered in Saint Louis, MO.
Byron L. Postma
2025-08-21 09:50:21
The 1 to 10 Amp AC adjustable trip range is handy. Circuit wiring diagrams are included. You can get a trip range lower than 1 Amp taking multiple loops through the coil, making it suitable for using almost any electronic device to trip the relay and turn on another device. I used this to build a relay box so that my main power amplifiers in my A/V system are turned on when I turn on my new A/V Receiver.My old receiver would work with a computer-type switching power strip (Smart Strip), but the new receiver evidently draws too little current (or too much when turned "off"), and it wouldn't work. I searched without success for another ready-made solution, but ended up having to build my own using this relay.IMPORTANT NOTE: This is NOT a plug-and play device and is designed as a component for industrial/commercial equipment. There are exposed 120 VAC contacts. For safety, you have to mount this in a closed electronic box, with a fuse, to provide protection. Don't buy this unless you are an experienced electronic hobbyist or engineer and can read a circuit wiring diagram.
Gary Green
2025-08-16 12:32:59
Excellent product. I used it to turn on the sound system with the tv. Mine had a (one pass) switching sensitivity of 10-100 amps and I used five loops to obtain 2-20 amp. I had measured the tv current at 3 amps and it worked well.... for a while. Then it would cut out after a few hours. To troubleshoot it, I used an ammeter during tv operation and sure enough, it started at 3 amps for the first hour or two, then gradually dropped to 1.8 amp! That’s when the relay kicked out and the sound went off. The fix was easy; I added five more turns for a total of ten to get a switching sensitivity of 1-10 amp and all works well now.
Drew Madison
2025-08-14 13:03:27
Works great. Using to power Salt Water Generator when pump is running.
Steven R. Lopez
2025-08-12 12:14:16
Works really well. Rewired my pool power system with this to trigger power to my pool chlorinator. Runs the chloranotor any time the pump is on and shuts down when the pump does. Basic wiring skills and additional relays were required.
Steve H.
2025-08-11 13:11:09
Good product, works well.
jason slicker
2025-07-15 19:55:41
Works great powering a small chemical injection pump for my well
ILS
2025-07-03 11:35:26
Works as intended.
Byron L. Postma
2025-06-18 14:55:49
The 1 to 10 Amp AC adjustable trip range is handy. Circuit wiring diagrams are included. You can get a trip range lower than 1 Amp taking multiple loops through the coil, making it suitable for using almost any electronic device to trip the relay and turn on another device. I used this to build a relay box so that my main power amplifiers in my A/V system are turned on when I turn on my new A/V Receiver.My old receiver would work with a computer-type switching power strip (Smart Strip), but the new receiver evidently draws too little current (or too much when turned "off"), and it wouldn't work. I searched without success for another ready-made solution, but ended up having to build my own using this relay.IMPORTANT NOTE: This is NOT a plug-and play device and is designed as a component for industrial/commercial equipment. There are exposed 120 VAC contacts. For safety, you have to mount this in a closed electronic box, with a fuse, to provide protection. Don't buy this unless you are an experienced electronic hobbyist or engineer and can read a circuit wiring diagram.
Gary Green
2025-05-25 16:25:36
Excellent product. I used it to turn on the sound system with the tv. Mine had a (one pass) switching sensitivity of 10-100 amps and I used five loops to obtain 2-20 amp. I had measured the tv current at 3 amps and it worked well.... for a while. Then it would cut out after a few hours. To troubleshoot it, I used an ammeter during tv operation and sure enough, it started at 3 amps for the first hour or two, then gradually dropped to 1.8 amp! That’s when the relay kicked out and the sound went off. The fix was easy; I added five more turns for a total of ten to get a switching sensitivity of 1-10 amp and all works well now.
Drew Madison
2025-04-24 18:32:35
Works great. Using to power Salt Water Generator when pump is running.
Steven R. Lopez
2025-03-19 13:55:41
Works really well. Rewired my pool power system with this to trigger power to my pool chlorinator. Runs the chloranotor any time the pump is on and shuts down when the pump does. Basic wiring skills and additional relays were required.
Steve H.
2025-02-06 10:43:34
Good product, works well.
jason slicker
2025-02-03 14:45:58
Works great powering a small chemical injection pump for my well
ILS
2025-01-17 12:34:27
Works as intended.
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