What is the application of current transformer?

Current transformers are used for protection, measurement and control in high-voltage electrical substations and the electrical grid. Current transformers may be installed inside switchgear or in apparatus bushings, but very often free-standing outdoor current transformers are used.

What is the main function of current transformer?

A Current Transformer (CT) is used to measure the current of another circuit. CTs are used worldwide to monitor high-voltage lines across national power grids. A CT is designed to produce an alternating current in its secondary winding that is proportional to the current that it is measuring in its primary.

What is the advantage of current transformer?

Current transformer advantages and disadvantages

Large currents can be measured safely. Isolates the high-current line from the measuring devices (like voltmeter and ammeter). Acts as a controlling device to operate protecting devices such as pilot lights and relays.

What is the working principle of CT?

During a CT scan, the patient lies on a bed that slowly moves through the gantry while the x-ray tube rotates around the patient, shooting narrow beams of x-rays through the body. Instead of film, CT scanners use special digital x-ray detectors, which are located directly opposite the x-ray source.

What is a current transformer?

A current transformer is a device used to produce an alternating current in its secondary, which is proportional to the AC current in its primary. This is primarily used when a current or voltage is too high to measure directly.

What are the types of current transformer?

The three types of current transformers in general use are the window, bar, and wound.

What is CT ratio?

Ratio. The CT ratio is the ratio of primary current input to secondary current output at full load. For example, a CT with a ratio of 300:5 is rated for 300 primary amps at full load and will produce 5 amps of secondary current when 300 amps flow through the primary.

What are the errors in CT?

There are two types of errors in a current transformer. They are ratio error and phase angle error.

Why CT secondary is grounded?

Secondary grounding of current transformers

To prevent the secondary circuits from attaining dangerously high potential to ground, these circuits have to be grounded. Connect either the S1 terminal or the S2 terminal to ground. For protective relays, ground the terminal that is nearest to the protected objects.

What are the function of the current?

The current() function simply returns the value of the array element that’s currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, current() returns false .

What is use of CT and PT?

CT and PT both are measuring devices used to measure currents and voltages. They are used where large quantities of currents and voltages are used. The role of CT and PT is to reduce high current and high voltage to a parameter.

Why do we use CT in the relay circuit?

CTs stands for Current Transformers. They are the devices that measure the current in a circuit. CTs are needed because the circuit’s current is much higher than the relay can handle. CTs step down the current to a low level safe to connect to the relay.

How CT is used for protection?

Protection CT

This enables the protective relays to measure fault currents accurately, even in very high current conditions. The secondary current is used to operate a protective relay which can isolate part of the power circuit experiencing a fault condition.

What is CT ratio?

Ratio. The CT ratio is the ratio of primary current input to secondary current output at full load. For example, a CT with a ratio of 300:5 is rated for 300 primary amps at full load and will produce 5 amps of secondary current when 300 amps flow through the primary.

What happens if CT is open circuited?

If CT is kept open-circuited, no current will flow in the secondary, and consequently, no secondary flux will be set up in the core. In absence of secondary current, the net flux will be higher than the flux generated in the core when CT is connected to load.