The IDR (residual differential switch) is a residual differential component that is, its principle of operation is based on the leakage of electrical energy, changing in small ways, the IDR is a device when it perceives a leakage current automatically turns off this circuit preventing this current of escape continue. This feature makes the IDR a safety component against electric shock.
The electric shock is a leakage of current, which escapes the electrical circuits and starts to circulate through the body of an individual, so the IDR is a device that aims to protect human beings against electric shock.
For this protection to occur effectively, two precautions must be taken:
- The IDR must be correctly sized for the circuit for which it is intended.
- The IDR must be working.
We will now show how to ensure that this IDR is working, for this a test must be done periodically on the IDR.
Every IDR has a test button on its body, this button is an internal simulation of current leakage that causes the IDR to trip every time this button is pressed.
In a very simple way this button allows the IDR to be tested, the procedure is to follow the following steps:
- The loads must be connected to the IDR circuit and this circuit energized;
- You must press their button, this process must be quick, as a long press can damage the IDR;
- The differential protection must act immediately by disconnecting the circuit, if it does not occur, proceed with additional checks.
- After the test, turn the IDR back on and put it into operation.
After pressing the button, if the IDR has not disconnected the circuit, this does not necessarily mean that the IDR has problems, some additional tests must be carried out to verify an IDR defect.
The first point is that for the IDR test circuit to work, some poles of this IDR must be occupied, at least two poles and these poles are specific, and may vary according to the model and manufacturer. In the body of the IDR there is a diagram that shows which poles must be occupied.
The image above shows 3 types of IDR and in these, a green circuit is highlighted between two poles, this is the internal test circuit that will only work when the poles in which they are internally connected in the IDR, are occupied.
For the test to work, the network frequency must be the same frequency indicated on the component or in the catalog provided by the manufacturer.
The IDR has an operating voltage that must be observed if this voltage is too low or high the IDR function test is compromised. A multimeter measurement is sufficient to ascertain the voltage value in the circuit.
Leakage currents in the load.
If the load connected to the IDR is showing a current leak, the circuit breaker will be tripped and, in case of an attempt to restart, it will trip. One option is to turn off the leaking charge and perform the test again.
It is recommended that the installation’s IDR’s be checked at least once a month and whenever there is an intervention in the electrical installation.
Manufacturers themselves such as Schneider Electric provide catalogs and technical materials for their components. In the Partner Portal, a platform created by Schneider, to assist in the training of professionals in electricity, it is possible to find many support materials on differential devices.
The IDR, despite being a not so new component, is still a mystery to many professionals. Many did not get trained after the first studies and hardly know about the new technologies, standards and components on the market. They end up in doubt about the test button of the IDR and do not check its operation.
With the completion of this IDR, it is possible to guarantee the safety of people and the installation, verifying the effectiveness of the IDR operation.