How Does This Current Sensor Close its switch?

[ThomsCircuit]

Updated BB with additional TP

 

[eTech]

.

 

[ThomsCircuit]

RockSeed True-RMS Clamp Meter​

Technique Data​

1. Current AC: Maximum input current：200A; True-rms measurement; Frequency response 50Hz-60Hz
2. Voltage DC: Input impedance:10 MΩ; Maximum input voltage: 600V DC
3. Voltage AC: Input impedance:10MΩ; Maximum input voltage:600V AC; True-rms; Frequency response: 45~1000HZ

 

[ThomsCircuit]

Measure the Pk voltage (+probe at TP B, and your -probe at TP GND) with a known AC load current and report back.

The meter has NOT arrived yet but i went ahead and did this test.
My meter measured the same 9.75-10v. The tool was under no load.
Makita LS1018 with a 13AMP 4300rpm motor

 

[eTech]

Interesting.
We need to be able to measure the AC load current to do meaningful testing.

 

[ThomsCircuit]

We need to be able to measure the AC load current to do meaningful testing.

The amp draw in the saw is 3.97.
it starts up at around 12A then quickly drops to 3.97A
The volt meter measured the same 9.75-10v.

 

[eTech]

What is the AC voltage measured across TP A and GND. Careful with this measurement.

 

[eTech]

What is the AC voltage measured across TP A and GND. Careful with this measurement.

before doing this….go to the HW store and buy a cheap battery operated multimeter. You can buy them for less then $10 USD.

 

[ThomsCircuit]

What is the AC voltage

I've have a MM but don't you mean DC Voltage?

 

[eTech]

I've have a MM but don't you mean DC Voltage?

No. TP A and GND is the current transformer winding. It has an AC voltage that is rectified thru the diode to point B.
TP A /Gnd should be about 20v AC.

 

[ThomsCircuit]

So at these points? OK will do

It has an AC voltage that is rectified thru the diode to point B.

 

[eTech]

Set your meter to AC volts, then measure +probe TPA, -Probe GND.

then set meter to DC volts, then measure DC with +probe TPB, -probe GND.

perform these measurement with and without an AC load.

report back.

BTW-it will be easier if you use a constant AC load like an incandescent light bulb (lamp) instead of you drill.

 

[ThomsCircuit]

BTW-it will be easier if you use a constant AC load like an incandescent light bulb (lamp) instead of you drill.

so at this time were not looking to trigger the relay at this time but measure AC DC voltage created by the CT. I can absolutely use a lamp. I did not realize the power tool had that low of an AMP draw. Seeing that the DC voltage at TPB was 10v I was expecting a much higher reading than the 4Amps.
I have a 100watt bulb. It should draw about an amp. Ill set up and report back.

 

[eTech]

so at this time were not looking to trigger the relay at this time but measure AC DC voltage created by the CT. I can absolutely use a lamp. I did not realize the power tool had that low of an AMP draw. Seeing that the DC voltage at TPB was 10v I was expecting a much higher reading than the 4Amps.
I have a 100watt bulb. It should draw about an amp. Ill set up and report back.

R4 should be a 1/2 watt (min) resistor (your schematic post #171).

A WORD OF CAUTION:
Never operate the CT without the load resistor (R4) connected to its secondary coil.
The CT secondary coil presents a HIGH VOLTAGE SHOCK HAZARD if operated without R4 connected to its coil.
It will generate literally THOUSANDS of volts.

This is why there was mention is earlier posts NOT TO BREADBOARD THE CT (because of the risk of an open circuit).

If you are satisfied with the way the peak detector is operating, then there is no need to test any further.
When ready to use, adjust the trigger by connecting an AC load that presents the desired current, then adjust pot U1 to energize or de-energize the relay.

 

[ThomsCircuit]

R4 should be a 1/2 watt (min) resistor (your schematic post #171).

R4 is a 1Watt resistor. (I HAVE SINCE RE-ORDERED THEM) For this project I ordered the highest wattage resistors available. All minimum 1/2watt

This is why there was mention is earlier posts NOT TO BREADBOARD THE CT (because of the risk of an open circuit).

I did not see that. I must have overlooked it. I would have not done that if I knew. Im sending the board out for production. I have re-named the resistors. Ive also added test points markings to the underside of the board for future testing.

 

[eTech]

R4 is a 1Watt resistor. (I HAVE SINCE RE-ORDERED THEM) For this project I ordered the highest wattage resistors available. All minimum 1/2watt

OK.

I did not see that. I must have overlooked it. I would have not done that if I knew. Im sending the board out for production. I have re-named the resistors. Ive also added test points markings to the underside of the board for future testing.

The TP's were intended as a communication tool for us but placing on the board is ok.

Suggestion:

It is common practice that when a PC board contains hazardous voltage potentials, a dashed-line and/or annotation is placed around or near the area to draw attention of the hazard to technicians for safety.

 

[ThomsCircuit]

It is common practice that when a PC board contains hazardous voltage potentials, a dashed-line and/or annotation is placed around or near the area

Absolutely. Ill look for an example and add it to the PCB

 

[ThomsCircuit]

Updated with warnings. Ive printed a few stickers to attach directly to the CT as well.

 

[ThomsCircuit]

Prototype is complete. Should be here in about 10 days

 

[eTech]

Prototype is complete. Should be here in about 10 days
View attachment 133298
View attachment 133300

Nice work.....