Electricity is one of history’s modern marvels, allowing us to perform feats and make machines no person before its use would have ever thought possible. Despite its usefulness, electricity can also be extremely deadly. Electricity is often used at high voltages in industrial applications and can cause harm to anyone who does not follow proper safety protocols.
Due to the possibility of workers being harmed, instruments known as current transformers (CTs) are regularly used to monitor electrical outputs, including voltage and current. This monitoring is necessary to prevent high-powered industrial machines from harming anyone. CTs, in turn, should also be tested to make sure they are functioning accurately using transformer testing instruments.
Here are three methods of CT testing to make make sure your CTs are functioning correctly and safely:
The ratio test is a CT test used to determine the CT’s ratio of primary current input to secondary current output. Both currents change at the same rates and in the same direction, meaning if the primary current doubles, then the secondary current doubles as well. This test is performed in order to prove the ratio of the CTs primary to secondary current is as specified by the manufacturer. Most CT meters are capable of performing the ratio test by applying a suitable voltage to the secondary winding of the CT and measuring the voltage from the primary winding side. Determining that the ratio of the CT is appropriate is necessary to ensure it is measuring current safely. If the machine is not measuring current accurately, a repair person or electrician could become injured when operating associated technology with higher voltages than the CT indicates.
Excitation (Saturation) Test:
Saturation testing is important for determining the safe use of a CT as it identifies the knee point against IEEE or IEC standards. This knee point is the point at which the CT is no longer able to output current in its specified ratio. When the CT is no longer able to output the correct amount of current the CT is said to be “saturated.” Testing for saturation is done by applying an AC voltage to the secondary winding of the CT and increasing the voltage in several steps until saturation is reached. Using energy meter testing equipment to correctly assess the saturation point of a CT is critical to electrical safety, as an inappropriate saturation point could compromise the entire CT.
Although the appliances in our homes use voltages typically between 110 to 250 volts, industrial machines use voltages many times higher. Such high voltages can be dangerous to workers and should be monitored closely using CTs. As such, a CT test using a CT testing instrument should be used routinely, to make sure the CT is accurately and safely measuring such dangerous voltages and preventing any workplace accidents from occurring.