# What is burden in current transformer?

## What is burden in current transformer?

The burden of CT is the maximum load (in VA) that can be applied to the CT secondary. The burden can be expressed in two ways. The burden can be expressed as the total impedance in ohms of the circuit or the total volt-amperes (VA) and power factor at a specified value of current or voltage and frequency.

## What happens when CT burden increases?

A higher value of burden basically extends the saturation characteristics of the CT core. During the condition of fault, the current increases to a higher value. This may lead to flow of high current (more than the rated value of connected meter) and hence may lead to its damage.

What is burden in a current and in a potential transformer?

Burden is nothing but an output apparent power of the instrument transformer. The burden of the transformer is normally denoted in VA. VA means Volt Amp.

What is burden in energy meter?

The burden is the termination impedance of the measuring instrument. The measuring instrument can be an analog or digital energy meter, a data logger or a recorder. Technically, the total burden for a CT is the internal winding resistance, the connecting lead resistance and the measuring instrument input resistance.

### How is burden calculated in CT?

Burden for Metering type CT = Total Burden of Meters (Digital/Analog Ammeter, Voltmeter, Power Meter, MFM, Transducer) which are in series with CT + The total VA of the Cables connecting CT and the Meters. Cable VA = (2L x R x I^2).

### What is burden in relay?

The total resistance of the secondary circuit of CT known as a burden is the sum of resistances of CT secondary winding,connecting wires(lead resistance) and the resistance of the relay/meter.

How do you check CT burden?

What is CT burden test?

The CT burden is the amount of impedance (AC Resistance) connected to the CT secondaries and is usually rated in ohms or volts. The manufacturer only guarantees CT accuracy up to a maximum burden rating and CT performance will degrade if the secondary burden is larger than rated.

#### What is burden in electrical engineering?

The load, or burden, in a CT metering circuit is the (largely resistive) impedance connected to the secondary winding. Items that contribute to the burden of a current measurement circuit are switch-blocks, meters and lenghty secondary conductors.

#### What is burden on PT?

The burden is the total external volt-amp load on the secondary at rated secondary voltage. The rated burden of a PT is a VA burden which must not be exceeded if the transformer is to operate with its rated accuracy. The rated burden is indicated on the nameplate.

What is Burden resistance of CT?

The load, or burden, in a CT metering circuit is the (largely resistive) impedance connected to the secondary winding. Typical burden ratings for IEC CTs are 1.5 VA, 3 VA, 5 VA, 10 VA, 15 VA, 20 VA, 30 VA, 45 VA & 60 VA. ANSI/IEEE burden ratings are B-0.1, B-0.2, B-0.5, B-1.0, B-2.0 and B-4.0.

What is burden resistance?

The term “burden resistance” is used to describe situations where each additional unit of current flowing through the device will increase the burden voltage by a fixed amount (e.g. if every milliamp flowing through the device would cause an extra millivolt drop, the burden resistance would be one ohm).

## How does burden affect the performance of a potential transformer?

The effects of Burden on the performance of a Potential Transformer are as follows: If we increase the Burden, the secondary as well as primary current will increase but as the primary voltage will remain constant (because primary of a PT is connected to the line), the secondary voltage will decrease. Therefore, the voltage ratio will increase.

## What happens when the value of CT burden is higher?

A higher value of burden basically extends the saturation characteristics of the CT core. During the condition of fault, the current increases to a higher value. If the Instrument Safety Factor (ISF) of CT is assumed to be 5 then CT metering core should saturate if fault current is more than 5 times the rated CT current.

How does an increase in the burden affect the voltage ratio?

If we increase the Burden, the secondary as well as primary current will increase but as the primary voltage will remain constant (because primary of a PT is connected to the line), the secondary voltage will decrease. Therefore, the voltage ratio will increase. Thus we see that increasing the Burden, increases the Error in the Ratio.

How is the burden of CT meters determined?

The burden of CT is basically decided on the basis of rough calculation of burden of leads and meters connected to the CT secondary. The calculation result is then inflated to be on safer side. However, while selecting the burden, one should be very careful as over estimation (more than required) may lead to selection of higher burden value.