There are several types of protection that can be used to protect transformers, including:
Overcurrent protection: This type of protection responds to high current levels by opening the circuit and interrupting the flow of electricity. It is used to protect the transformer from damage caused by short circuits and ground faults.
Differential protection: This type of protection compares the current flowing into a transformer with the current flowing out of the transformer. If there is a difference between the two, it is an indication of a fault and the circuit is opened to protect the transformer.
Temperature protection: This type of protection uses temperature sensors to monitor the temperature of the transformer. If the temperature exceeds a certain threshold, the circuit is opened to prevent overheating and damage to the transformer.
The temperature protection setting range for a transformer can vary depending on the type of transformer and the specific application. However, in general, the typical temperature protection setting range for a transformer is between 55 and 80 degrees Celsius (131-176°F).
The lower limit of the temperature range, 55 degrees Celsius, is typically set as the alarm point, where an alarm will sound or a signal will be sent to the control system to indicate that the transformer's temperature has reached a dangerous level, but it hasn't tripped yet.
The upper limit of the temperature range, 80 degrees Celsius, is typically set as the trip point, where the temperature protection system will trip the transformer and interrupt the flow of electricity to prevent damage caused by overheating.
It's important to note that the temperature protection setting range can vary depending on the transformer's design and the specific application. For example, the setting range for a transformer used in a sub-station will be different than a transformer used in a power plant.
Furthermore, the setting range can be adjusted based on the type of cooling system used, for example, the setting range for a transformer with natural air cooling will be different than a transformer with forced oil cooling system.
In general, the temperature protection setting range is determined by the manufacturer based on the transformer's design and the specific application, and it should be checked and confirmed during the commissioning process and regularly during the transformer's operation.
Earth Fault protection: This type of protection detects earth faults in the transformer winding and trips the circuit breaker to isolate the faulty transformer.
Voltage protection: This type of protection monitors the voltage level of the transformer, If the voltage exceeds a certain limit, the circuit breaker will trip to protect the transformer from damage.
Oil protection: This type of protection monitors the oil level and temperature of the transformer. If the oil level is low or the temperature is too high, the circuit breaker will trip to protect the transformer.
Distance protection: This type of protection uses a relay that compares the impedance of the faulted section to the impedance of the healthy sections, the relay will trip the breaker if the impedance is within the protection's zone of protection.
Restricted earth fault protection: This type of protection uses a specialized relay to detect earth faults in the transformer winding that the current is restricted, this allows to locate the faulted section more accurately and quickly.
Oil surge relay is a type of protection device used to protect transformers from damage caused by oil surge. Oil surge can occur when there is a sudden change in the oil level inside the transformer, such as a sudden increase or decrease. This can be caused by factors such as a fault, a change in the load on the transformer, or a change in the temperature of the oil.
The oil surge relay is typically installed in the transformer's conservator tank, which is the tank that holds the oil that cools and insulates the transformer. The relay is designed to detect changes in the oil level and respond by tripping the circuit breaker, which interrupts the flow of electricity to the transformer and prevents damage.
The oil surge relay operates by using a float and a set of contacts. The float is connected to a lever that moves when the oil level changes. The contacts are connected to the circuit breaker and are normally closed. When the oil level changes, the float moves and the lever opens the contacts, tripping the circuit breaker and interrupting the flow of electricity to the transformer.
The oil surge relay is typically set to trip the circuit breaker when the oil level changes by more than a certain amount, typically a few centimeters. The exact trip point can be adjusted to suit the specific requirements of the transformer and the electrical power system in which it is installed.
Overall, the oil surge relay is an important protection device that helps to ensure the safe and reliable operation of the transformer by protecting it from damage caused by oil surge.
Buchholz relay is a type of protective relay that is used to monitor the health of an oil-immersed transformer. It is designed to detect gas or oil leaks within the transformer, as well as other internal faults that could damage the transformer. When a fault is detected, the relay will trip and shut off the power to the transformer, preventing further damage. It is commonly used in large power transformers and is an important component of the transformer's protection system.
A pressure relief valve (PRV) is a type of protection device used to protect transformers from damage caused by excessive pressure. The pressure inside a transformer can increase due to a variety of factors, such as a fault, a change in the load on the transformer, or a change in the temperature of the oil.
The PRV is typically installed on the transformer's conservator tank, which is the tank that holds the oil that cools and insulates the transformer. The PRV is designed to detect changes in the pressure inside the tank and respond by releasing the excess pressure to the atmosphere. This prevents damage to the transformer and ensures the safe and reliable operation of the electrical power system.
The PRV operates by using a spring-loaded valve that is set to open at a specific pressure. When the pressure inside the tank exceeds this set point, the valve opens and releases the excess pressure to the atmosphere. The valve will close again when the pressure inside the tank drops below the set point.
The set point of the PRV can be adjusted to suit the specific requirements of the transformer and the electrical power system in which it is installed. It is also important to regularly check and maintain the PRV to ensure its proper functioning.
Overall, the PRV is an important protection device that helps to ensure the safe and reliable operation of the transformer by protecting it from damage caused by excessive pressure. It is a common practice to have the PRV installed in combination with other protection devices such as oil surge relay and temperature protection to provide a comprehensive protection system.
A magnetic oil gauge (MOG) is a type of protection device used to monitor the oil level inside a transformer. The oil level is an important factor in the safe and reliable operation of a transformer, as the oil is used to cool and insulate the transformer. A lack of oil can cause the transformer to overheat and suffer damage.
The MOG is typically installed inside the transformer's tank and it operates by using a magnetic sensor that detects the oil level. The sensor is connected to a gauge or indicator that displays the oil level, and it can also be connected to an alarm or trip mechanism that interrupts the flow of electricity to the transformer when the oil level is too low.
The MOG operates by using a magnetic float that is suspended inside the transformer tank, the float is connected to a magnetic sensor that detects the position of the float, when the float moves up or down with the oil level, the sensor sends a signal to the gauge or indicator, which displays the oil level. Additionally, the MOG can be connected to an alarm or trip mechanism that interrupts the flow of electricity to the transformer when the oil level is too low, this will prevent damage to the transformer caused by lack of oil.
Overall, the MOG is an important protection device that helps to ensure the safe and reliable operation of the transformer by monitoring the oil level inside the transformer. It is a common practice to have the MOG installed in combination with other protection devices such as oil surge relay and pressure relief valve to provide a comprehensive protection system.
Electrical transformer protection is a system of devices and techniques that are used to protect transformers from damage and ensure the safe and reliable operation of the electrical power system. The main goal of transformer protection is to detect and respond to abnormal conditions, such as short circuits, ground faults, and overheating, before they can cause damage to the transformer or other equipment.