0-5A Input (x3) on M221

[simongallagher]

Hello all,

I need to build a system that will operate various AC contactors and 'lock' them out for a predertimed time when a set current value is breached, across three phases of an incoming electricity supply.

I my need hundreds of these, so they need to be efficient in terms of cost.

I am planning to use 5A CTs on the electricity cables (x3), and need to read these values in the PLC.

I am struggling to find the most efficient way to do this, based on:
- The M221 has 2 analogue inputs (0-10V)
- plan CTs are cost efficient
- Need to convert the 5A analogue signal either to 0-10V (need an extra PLC module), 4-20mA (need an expansion board) or to digital, but what is the best hardware?

Any advice much appreciated on the best hardware configuration to use (I cant find any 5A to digital converters that are cost efficient for 3 phases).

 

[danw]

If by 'digital' you mean a switch that trips at an AC current setpoint, then here's a Dwyer current switch which might do the 'digital' part
https://www.lesman.com/mcs-111050

Then there are converters to convert th 0-5A AC output from a CT to a dc signal:

https://www.datexel.com/ac-current-converter-dat5023iac-a.html
https://www.nktechnologies.com/engineering-resources/converting-ct-signal-standard-4-20-ma-output/

 

[Bit_Bucket_07]

I've had success measuring AC current with Veris instruments:
https://www.veris.com/126822/category/current-monitoring

This is one of their setpoint relays:
https://www.veris.com/995242/product/veris-h608-current-switch

 

[Corsair]

I may be wrong but I think you may need to investigate quantity pricing on a communicating power meter forr this situation. Get one with built-in cts??

 

[Bit_Bucket_07]

Hello all,
(I cant find any 5A to digital converters that are cost efficient for 3 phases).

I suspect that setpoint relays for digital inputs are going to be far less expensive than either analog IO or current transmitters with communications capability.

I would also consider monitoring all three phases of each motor overkill if you're simply seeking to determine motor load during normal operation versus monitoring the motors for phase to phase current imbalance.

 

[RDS]

Hello all,

I need to build a system that will operate various AC contactors and 'lock' them out for a predertimed time when a set current value is breached, across three phases of an incoming electricity supply.

I my need hundreds of these, so they need to be efficient in terms of cost.

I am planning to use 5A CTs on the electricity cables (x3), and need to read these values in the PLC.

I am struggling to find the most efficient way to do this, based on:
- The M221 has 2 analogue inputs (0-10V)
- plan CTs are cost efficient
- Need to convert the 5A analogue signal either to 0-10V (need an extra PLC module), 4-20mA (need an expansion board) or to digital, but what is the best hardware?

Any advice much appreciated on the best hardware configuration to use (I cant find any 5A to digital converters that are cost efficient for 3 phases).

These may work for you:

https://www.phenixcontrols.com/Current_Sensor/Three_Phase/

 

[Tom Jenkins]

These will let you eliminate the C/T. Available as switches:
https://www.automationdirect.com/ad...itches&categoryId=0&TxnNumber=-1&searchqty=10

or transmitters for analog input: https://www.automationdirect.com/ad...mitter&categoryId=0&TxnNumber=-1&searchqty=50