AC Current Sensing Switch 0-200A Normally Closed Current Sensor Monitoring Relay (NC200)

Upgrading a fixed speed poolpump and SWCG to a VS pump requires a means of removing power from the SWCG when the pump internal timer turns the pump off. Using the normally OPEN version to drive a power contactor/relay, controls power to the SWCG. In my application, L1 of the motor supply is passed through the sensor (red #12 wire in photo) to detect when the pump is off, which opens sensor output and relay, removing power from SWCG. The adjustment allows setting trip current for any pump speed. So far this has worked PERFECTLY.

Created a junction box with this current sensor to turn on an inline 6 inch fan whenever the microwave was powered on.

I tried both the 30A and 50A normally-closed relays (NC30 & NC50), and both had relay contacts that never changed state. They just stayed open whether the current threshold had been met or not. Even when disconnected, even straight out of the box, the contact were open on the normally-closed relays. The LED lights would come on when current passed through, but the relay didn't change. So if you want a pretty light that comes on, hey great, but if you need relay action look at some other product.

I’ll buy it again , it works from the very beginning. Description sucks but for smart people it will work

Works as advertised. Non-invasive current detection transformer for 240VAC primary wiring

This sensing relay seems to be available from a number of suppliers under different names but they look identical and likely come from the same Chinese factory. I have purchased units under at least two different names.The title of listing says these relays are "normally closed" whichever sub model number you select, while if you look carefully the "color" for each model changes from "normally open" (NO) for some model numbers to "normally closed" (NC)for others. Make sure you select the model based not only on current range you need but on whatever you need either NO or NC . This could be a significant safety risk if you don't pay attention to which "color" you are choosing.I have an electronics degree so I just set the current sense threshold using a 6V mains transformer and some resistors to put different currents through a test wire through the device and then adjusted the screw setting to desired threshold. I threaded a wire through the current sense hole in the sensor to pass the test current through the device thus avoiding dealing with line voltages.I did test the ends of the adjustment range and the low minimum current setting (turned counter clockwise until a slight clicking sound is heard) and the maximum current setting (turned clockwise until clicking sound is heard). This showed that the claimed minimum and maximum current values specified by the vendor (0.25A-30A for my model) were about right Many home users won't have knowledge or equipment to do full testing like that but here is a crude method which may help get you into the right ballpark:(Many reviewers complain about vendor not giving information on threshold setting adjustment.)The small screw that sets current threshold turns many times to go from min to max, (it's most likely 20 full turns as many common small multi-turn potentiometers are 20 turns, but I have not counted the number of turns on my unit and the method below helps you identify that)1) turn the adjuster screw counter clockwise until you hear a faint clicking noise as the potentiometer adjust hits the end of travel at its minimum current setting. The potentiometer you are adjusting is not damaged by turning more turns beyond the point where clicking occurs. The clicking is a small spring wire that prevents the potentiometer from moving too far.2) Turn the screw clockwise counting full turns until you hear the faint clicking again this is the maximum current setting.3) Now at least you can set a percentage (turns counts) of the range from the max current setting to the minimum position. A question arises are turns counts a linear function of current range? in other words if you go from say max current position counter clockwise 10 turns (assuming total of 20 turns range) towards minimum current ,is that 10 setting approximately at half the maximum current setting? I did not test if it is linear, but at least assuming linear is a rational starting point which can get you started and then you can do some tests with your actual load.Hopefully vendor will correct confusion information on NC and NO devices

This unit worked great for about a month, and has given out. Contacts don't close anymore when current is detected, no matter the adjustment. I also wish there was a dial of sorts to see where your approximate amp setting was on.

The media could not be loaded.  Worked well for my needs, to turn one appliance off when another turned on. Be careful with the amperage, can only handle .3 amps on the terminals, needs to be used in conjunction with a contactor.