AZDelivery 3 x ACS712 5A Range Current Sensor Measuring Module compatible with Arduino including E-Book!

Brilliant in that you can monitor current to a motor or coil or fan etc and if the current gets too big use the Arduino or Pi to turn the device off -- before any damage occurs. This little board is a must really for any circuit that pumps a lot of amps (like 2A or more) and is controlled by software. Use PWM = 0 to turn off the current is one way.

Don't know where to start but this 30A unit is crazy on a number of levels - if has a connector which if you read the markings state 10A! The pcb tracks are tiny so definitely won't hold 30A current. Also the pcd tracks are so close together that you will no doubt have cross arching even if you did put 30A through this.

Works perfectly and great value. The instructions with it were great too!