| External
Current Transformer An external transformer can be used to monitor remote loads or where the steady state load current exceeds 40 amperes. Select a current transformer (CT) that is rated for the load being monitored and an ECS with a trip point range of 0.5 to 5 amperes. The CT secondary should be in the range of 0 to 5 amperes. The burden rating of the secondary should be a minimum of 0.5VA. Pass the current-carrying wire through the hole in the CT. Make one pass of the CT’s secondary wire through the toroid on the ECS. When properly connected, the CT’s secondary will appear to be shorted. The ECS trip point may now be adjusted. |
 |
| Multiple
Turns to Increase Sensitivity The sensitivity of a current sensor may be increased by passing the current carrying wire through the toroid two or more times. The sensing range becomes the standard range divided by the number of wire passes through the toroid. For example, an ECS with a 0.5 to 5 amp trip range would sense 0.25 to 2.5 amps with two wire passes through the toroid. For four wire passes, the range would be 0.125 to 1.25 amps. The burden increases each time the wire is passed through the sensor. If the burden was 0.5VA for one pass, it would be 1 for two passes, and 2 for four passes. | ||||||||||||||||||||
|
 |
 |
||||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
 |
|||||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
