How to connect wires to this module ?

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If I want to measure current through a wire then we actually measure it in series by cutting the wire and putting a ammeter in between the cut wires. So, should I do a similar thing here that is cut the wire and join the cut terminals to Sensor module?
 
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Yes, the IP+ and IP- terminals shown in the schematic of the last tutorial is the current path to be measured.

Also, reference the device datasheet for a similar schematic:

Allegro ACS712

The datasheet also offers several schematics of typical applications.

BigDog
 
I have one more question.

I have a relay 1 Form A type. T9AS1D12-5 tyco. It switches the Phase wire of the motor. Can I connect like this ?
 

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Be aware, as the ACS712 is a Hall effect device, it must be keep as far away as possible from sources of magnetic fields, such as motors, relay coils, etc.

Also, keep an eye on the maximum current flow, as the ACS712 does have current limits based on the specific model.

Consider carefully the potentially large current spikes which can generated by inductive elements such as motors and relay coils, ensuring these potentially large current spikes do not exceed the devices maximum specifications.

The ACS712 is both a high and low side sensor, therefore it can be positioned anywhere along the current path to be monitored, therefore position it as to provide the best distance and shielding from stray magnetic fields, produced from devices such as motors, relay coils, etc.


BigDog
 
How much distance should be provided between Relay and motors? I am using the sensor to measure the current drawn by motor which is controlled by a relay. The relay is T9AS1D12-5 tyco T relay.


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How much distance should be provided between sensor and Relay + motors?
 
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Before consider that issue, the characteristics and specifications of the motor must be known.

Also, describe any snubber circuits which exist on that current loop.

And confirm the ACS712 on your module is indeed the 30A version.


BigDog
 
Read the datasheet then ask a better question.


To reduce stray noise shield your signal wires or use twisted pair with ferrite or torroid CM choke. Also twist high voltage wires to and from relay to reduce emissions during switching. An AC snubber (RC) across contacts may be necessary too. Relay coil also needs snubber diode across it if not already.
 
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Motor is 230V AC, 50HZ, 1 phase type. It is a pump 1.5 hp. Nothing special about it. There are no snubber circuits. Yes, the sensor measures -30 to +30A, The link is in the first post of this thread. I have made and I am getting 0.04A for no current.

Code C - [expand]
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acs712SensorValue = (double)analogRead(ACS712);            
acs712SensorValue = (acs712SensorValue * 0.0742) - 37.88;




Sensor out 2.5V = 0 A.
 
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Again, read the chip datasheet. The zero current output voltage (ZCOV) is VCC × 0.5 or 2.5V in your case. Overall error is 1.5% of full scale at 25'C and there is a temperature coefficient of error in spec.

1.5% of 30A = 0.45A you are getting 0.04A with no current! If you want better results, add calibration routine to correct offset for ZCOV condition and add temperature correction.
 
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