Electricity helps us daily, throughout the day, but it can also end up offering dangers, for this there are some devices that are able to protect you and your family from electric shocks, regardless of whether it is through direct or indirect contact, the DR is one of those devices. Learn what a DR is, how it works, what is the difference between a common and a super immunized DR, and for what situations each one is indicated, come on guys!
What is DR?
DR stands for Residual Differential, which is also known as Residual Differential Switch (IDR), both refer to the same device, but differ from DDR.
The Residual Differential device within an installation is responsible for disconnecting the circuit as soon as a current leak greater than the determined value, which is generally 30mA, is detected, thus preventing the electric shock from being fatal.
The sensitivity of the DR can vary according to the device and application, the value of 30mA is purposeful, as this is the maximum current that a person can withstand without suffering damage.
It is important to note that the Residual Differential device does not prevent the person from taking an electric shock! The DR allows shock, but what does not allow the person to suffer greater damage is the time that the electrical discharge will last, being for an extremely short period, which is the response of the DR in relation to current leakage.
There are other residual differential devices that are intended for other applications, for example, for protection of machines and equipment, in addition to fire protection, which varies between 300mA to 1000mA to be activated, which changes according to the device.
How does a DR work?
The DR device permanently measures the vectorial sum of the currents that travel through the conductors of a circuit. If the electrical circuit is running smoothly, the vectorial sum of the currents in your conductors will always be practically zero.
The moment an insulation failure occurs in one of the equipments powered by the same circuit that the DR is connected to, a leakage current will appear, so the moment it happens, the vectorial sum of the currents in the conductors being monitored by the DR will no longer be null, this is how the device immediately detects the difference between the input and output currents and opens the circuit immediately.
The operation is the same when someone touches a living part of the circuit, whether directly or indirectly the current will circulate through that person’s body, and there is also an imbalance in the vectorial sum of the currents.
Difference between a common DR and a Super Immunized DR
Just like traditional DR, the super-immunized Residual Differential is also developed with the objective of protecting people against electric shocks and fire principles. It has a signal processing function and provides much more accurate shots, like the Acti 9 iID models developed by Schneider Electric using an unprecedented and innovative technology.
However, in the common DR, a high-frequency current, generated by lightning strikes, switching on the network or by a computer network, can be seen as a failure, causing it to be triggered unnecessarily.
The Residual Differential device with the signal processing function is already able to identify whether the current really poses a risk or if it is just one of those phenomena that ordinary DR is not able to differentiate.
Another advantage of DR Super Immunized is that it can be used in humid or polluted environments with aggressive agents. In addition, the device has superior performance to traditional DR, supporting higher current and frequency. DR Super Immunized is also indicated for industrial installations, mining, sanitation, hospital and data centers.