Why on-load tap changer has separate oil?
To prevent contamination of the tank oil and facilitate maintenance operations, the diverter switch usually operates in a separate compartment from the main transformer tank, and often the tap selector switches will be located in the compartment as well.
How does a load tap changer work?
This is accomplished by installing a load tap changer onto the transformer. The LTC actually changes the transformer turns ratio by moving among a number of access points or “taps” on one of the two windings, thus either raising or lowering the voltage supplied to the customer.
How does a no-load tap changer work?
No-load tap changers (NLTC), also known as de-energized tap changers (DETC), off-load tap changers, and, off-circuit tap changers (OCTC), employ manually operated switching equipment that changes the transformer turns ratio of the three phases simultaneously and by the same amount.
What is the difference between on-load and off load tap changer?
In OLTC, The tap changing operations can be done while the transformer is in operation/service. But in Transformers with Off Line tap changer, Tap changing operations are done while the Transformer is OFF /de energized condition.
What is off nominal turns ratio?
The off-nominal tap ratio determines the additional transformation relative to the nominal transformation. This value normally ranges from 0.9 to 1.1 (1.0 corresponds to no additional transformation). For phase-shifting transformers the phase shift value normally ranges from about -40° to 40°.
What should be the range of on-load tap changer of a transformer?
An LTC (the casing is not normally transparent) The amount an LTC can regulate the output voltage varies, although a typical range is ±10% of rated output voltage. For large distribution transformers, it is typical to have 16 taps above and 16 taps below the rated voltage.
Which side is tap changer used and why?
The tap changer is placed on high voltage side because: 1. The HV winding generally wound over LV winding hence it is easier to access the HV winding turns instead of LV winding.
On which side of transformer tap changer is provided?
Tap changer can be located on primary side or secondary side. However it will be placed on high voltage winding side.
On which winding of transformer tap changer is provided?
A tap changer is usually installed on a high voltage section of a two-winding transformer, due to the low current in that area. The changers are also provided on high voltage windings of an electrical transformer if there is sufficient control of voltage.
What is the disadvantage of off load tap changing transformer?
Off-Load Tap-Changing Transformer : The disadvantage of this scheme is whenever the tapping is to change load must be disconnected first from the transformer thus it is referred to as off-load tap-changing.
Can a tap changing under load transformer be sued?
Tap-changing Transformers In order that the supply may not be interrupted, on-load tap changing transformer are sued. Such a transformer is known as a tap-changing under load transformer. While tapping, two essential conditions are to be fulfilled.
Why choose ABB Uz tap changers?
Introduction The UZ range of on-load tap-changers manufactured by ABB has been developed over many years to provide maximum reliability. The simple and rugged design gives a service life equal to the service life of the transformer. Minimum maintenance is required for trouble-free operation.
Why choose a Uze/uzf tap-changer?
The design allows ready access to all parts, making inspection and maintenance quick and simple. The on-load tap-changer type UZE/UZF is placed in an oil- filled tank separated from the transformer tank. The motor- drive mechanism is attached to the side of the tap-changer tank.
How is the tap-changer controlled?
Normally the tap-changer is controlled by a voltage regulator and no manual operation of the tap-changer and the motor- drive mechanism is needed. Maintenance schedule CAUTION
What happens when a load tap changer fails?
When a transformer unexpectantly fails due to a load tap changer (LTC) problem, revenues are lost as production comes to a standstill. Equipment age, extreme usage, lack of replacement parts, and declining availability of technical experts all add to the growing risk of failure of transformer LTCs.