What happens when off load tap changer operated on load?
In case of Off-Load Tap Changer, it must be ensured that Transformer is de-energized as Off-Load Tap Changing is not Make Before Break type. If the Off-Load Tap Changer is used while the Transformer is energized, heavy sparking will take place which will damage the winding and insulation.
What are the differences between off load and on load tap changers?
On load tap changers are the ones where taps in the transformers change automatically as per loads variations. The off load tap changers are Non automatic and are those transformers where you can change the tap manually, if required, but with the transformer completely DE-energized.
Why on load tap changer are used?
The purpose of a tap changer is to regulate the output voltage of a transformer. It does this by altering the number of turns in one winding and thereby changing the turns ratio of the transformer. An OLTC varies the transformer ratio while the transformer is energized and carrying load.
Why OLTCs on load tap changer are used?
On-load tap-changers (OLTCs) are indispensable in regulating power transformers used in electrical en- ergy networks and industrial applications. OLTCs enable voltage regulation and/or phase shifting by varying the transformer ratio under load without interruption.
What is the function of tap changer?
The purpose of a tap changer is to regulate the output voltage of a transformer by altering the number of turns in one winding and thereby changing the turns ratio of the transformer. There are two types of tap changers: a de-energized tap changer (DETC) and an on-load tap changer (LTC).
What are the disadvantages of tap changing transformers?
However, its major disadvantage is that although two thyristor are ON over short periods during the tap-changing process, it is permanently connected to the circuit of the deviation switches and it probably gets burnt. This may therefore reduce the reliability of the system.
How do you calculate tap changer?
V1/V2 = N1/N2 or V1·N2 = V2·N1 indicates that, to keep the equation in balance with primary voltage and secondary winding turns fixed, either V2 or N1 must be adjusted. Since the objective is to raise V2 back to nominal, then N1 must be reduced. Therefore N1 must be reduced by (1 – 0.974) = 0.026 or 2.6 %.
What is the purpose of a tap changer?
How does on load tap changer work?
On-load tap changers (or circuit tap changers), as the name suggests, permit tap changing and hence voltage regulation with the transformer on-load. Tap changing is usually done on the HV winding for two reasons: Because the currents are lower, the tap changer contacts, leads, etc., can be smaller.
What does on load tap changing transformer do?
Definition: An On-Load Tap Changing Transformer (OLTC) consists of an open load tap changer, it is also known as an on-circuit tap changer (OCTC). They are used in areas where there is an interruption in the power supply due to an unacceptable tap change. The ratio of the number of turns can be changed without breaking the circuit.
What is a no load tap changer?
No-load tap changer. No-load tap changer (NLTC), also known as Off-circuit tap changer (OCTC) or De-energized tap changer (DETC), is a tap changer utilized in situations in which a transformer’s turn ratio does not require frequent changing and it is permissible to de-energize the transformer system.
What is a tap changer transformer?
What is a Transformer Tap Changer. A tap changer is a device fitted to power transformers for regulation of the output voltage to required levels. This is normally achieved by changing the ratios of the transformers on the system by altering the number of turns in one winding of the appropriate transformer/s.