Today, we are exploring about Why not use fuse in current transformer?, Why is CT always short circuited?, Why do we use fuse in PT?
Why not use fuse in current transformer?
Fuses are generally not used in current transformers (CTs) because CTs are designed to operate under normal load conditions without the risk of overcurrent or short circuits. CTs are primarily used to measure or monitor electrical currents in power systems, and they are designed to provide accurate current measurement over a wide range of operating conditions. Unlike other components in a power system, such as cables or conductors, CTs do not carry current continuously and are not subject to the same risks of overloading or short circuiting.
Why is CT always short circuited?
The CTS are always short during normal operation to ensure proper current measurement and to prevent high voltages from appearing across the secondary winding. When a CT is connected to a measurement or protection device, such as a meter or relay, the secondary winding of the CT is usually shorted to provide a low impedance path for current to flow. This short circuit condition ensures that the voltage across the secondary winding remains low, allowing accurate current measurement without the risk of damaging the measuring device.
Why do we use fuse in PT?
Fuses can be used in potential transformers (PT) to provide overcurrent protection and to prevent damage to the transformer in the event of a fault or overload. PTS are used to resign high voltage signals to a lower voltage level suitable for measurement or control purposes. In some applications, particularly where PTs are connected to sensitive equipment or instrumentation, fuses may be installed in the circuit to protect the PT from excessive currents which could damage the winding insulation or other internal components.
Fuses are commonly used in transformers, including current transformers (CTS) and potential transformers (PTS), to provide overcurrent protection and to prevent damage to the transformer in the event of a fault or short circuit . In transformer circuits, fuses are usually installed in series with the primary or secondary winding to limit the flow of current in the event of an overload or short circuit. When the current exceeds the rated capacity of the fuse, the fuse will blow or open, interrupting the circuit and protecting the transformer from damage.
The CTS must not be open circuited during normal operation, as this can result in dangerously high voltages across the secondary winding. CTs are designed to operate with a low impedance load connected across the secondary winding, as a metering or protection device. If the secondary winding of a CT is open circuited, the voltage across the winding can rise to potentially dangerous levels, posing a risk of electric shock or damage to connected equipment. Therefore, it is essential to maintain a short circuit across the secondary winding of a CT during normal operation to ensure safe and accurate current measurement.
We trust this discussion of Why not use a fuse in the current transformer? has answered your questions.