HOW TO INSTALLATION CT (Current Transformer)

Tips for Installing a Current Transformer - Current Transformer or current transformer is a transformer that functions to measure (metering) the current passing through a conductor. For the purpose of measuring the current, the Current Transformer must be installed in series with the conductor to which the current will be measured. With the ratio between the primary winding (N1) and the secondary winding (N2), the current passing through a conductor can be measured with a measuring device such as an Amper meter or other digital measuring instrument.

Example: If we use a CT (Current Transformer) with a ratio of 200/5 A, this means that if the current passing through a measured conductor is 100 A, then the value of the current on the secondary side is:

Is = 5 x 100/200

Is = 2,5 A

The measured 2.5 A value is then converted back to a 100 A value on the reading display.

Apart from being a current meter, Current Transformer is also used as part of a protection device, such as over current, overload, differential current and so on.

In its use, there are several things that we must pay attention to for safety factors and to prevent damage to the Current Transformer, as below:

1. When we want to connect a current transformer (current transformer) to a measuring device or protection device, for security, one of the terminals must be connected to the ground. (Picture 1)

2. The secondary winding of the current transformer must not be open circuit when it is installed in series on a conductor.

If the conductor is installed with a current transformer, and is not connected to a measuring device or protection device, then the secondary terminal of the current transformer must be shorted and grounded (Figure 2).

3. For current transformers that have taping, namely several secondary terminals whose output can be selected as needed, the unused terminal must be left open. (Figure 3)

4. Current Transformer which uses a capacitor for divider taping (capacitive divider tap -Ck), then the Ck terminal must be connected to a metering device or protection device. If the Ck terminal is not used, then the Ck terminal must be grounded. (Figure 4)