What is the main application of the differential relay?
What is the main application of the differential relay?
Current-differential relays. Current-differential relays are typically used to protect large transformers, generators, and motors. For these devices detection of low level winding-to-ground faults is essential to avoid equipment damage.
What is the differential protection of transformer?
Differential protection is a unit-type protection for a specified zone or piece of equipment. It is based on the fact that it is only in the case of faults internal to the zone that the differential current (difference between input and output currents) will be high.
Why differential relay is used in transformer?
Similar to bus protections, transformers are protected by differential relays. Inter-winding faults (short circuits) and ground faults within power transformers can be detected by this protection scheme. Failure to detect these faults and quickly isolate the transformer may cause serious damage to the device.
How many relays does a transformer have?
Relays for Transformer Protection
| SL | Voltage Ratio and Capacity of Transformer | Common Relays |
|---|---|---|
| 9 | 400/220KV 315MVA | Differential Relay Overflux Relay Buchholz Relay OLTC Buchholz Relay PRV Relay OT Trip Relay WT Trip Relay Over Load (Alarm) Relay |
Which type of relay is used in transformer?
How is differential protection work in a transformer?
Transformer Differential Protection Scheme works by using two separate quantities calculated from the primary current (IW1C) and secondary current (IW2C). SEL787 and SEL 387/587 Transformer differential relay is used for this discussion. Other similar relays use similar concepts through the actual terminology could be different.
When to use differential transformer protection?
Differential protection schemes are mainly used for protection against phase-to-phase fault and phase to earth faults.The differential protection used for power transformers is based on Merz-Prize circulating current principle. Such types of protection are generally used for transformers of rating exceeding 2 MVA.
What is operating coil of differential relay?
The operating coil is connected to the mid-point of the restraining coil . The reason for using this modification in circulating current differential relay is to overcome the trouble arising out of differences in CT ratios for high values of external short-circuit currents.
What is a current differential relay?
The differential relay is one that operates when there is a difference between two or more similar electrical quantities exceeds a predetermined value. In differential relay scheme circuit, there are two currents come from two parts of an electrical power circuit.
