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Why it is necessary to disconnect the load when change the tap?
Wiki User
∙ 12y ago
when the load is connected to draws some current. while changing the tap of the transformer the tappings related to the winding is changed , so the load current affects the transformer. hence while changing the tap it should be noted that
AnswerThere are two types of tap-changing mechanism -'off-load' and 'on-load'. Off-load tap changers physically disconnect the winding when changing from one tap setting to the next. Accordingly, the circuit is temporarily broken, and dangerous arcing will take place if the transformer is energised. Therefore off-load tap changers require that the transformer is disconnected while the mechanism is operated.
On the other hand, 'on-load' tap changers use a mechanism which incorporates a 'make before break' contact arrangement, ensuring that no break is made in the circuit as the mechanism moves from one tap setting to the next, enabling it to operate with the transformer energised and supplying load. On-load tap changers are usually automatically operated, although this feature can be overridden and operated manually.
Wiki User
∙ 12y ago
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How does on load tap changers operate?
On-load tap-changers are operated by an electric motor, often by driving a flywheel mechanism. The operation of the tap-changer is controlled by an AVR (automatic voltage regulator) which monitors the transformer's secondary voltage.
What is no load tap changing in transformer?
It changes the tap while it is operation (hence "on load"). This allows real-time voltage regulation for the transformer secondary (as load picks up, causing the voltage to sag, the LTC can tap up, increasing the voltage).
What is the difference bet manual off Tap changer and auto tap changer in Distribution Transformers?
automatic tap changing transformers can change their tap setting on their own, manual tap means a person has to manually go out and change the tap setting
Why tap changer is required?
Tap changers are used to change transformer winding ratios by a specified amount (+/- 10%, for example). This allows more voltage control of one side with respect to the other. For a distribution transformer, as load increases, the voltage will sag. If it sags too far, a tap changer will be required to raise the voltage to acceptable values.
Why tapping are provided in high voltage winding of transformer?
Tappings are provided in order to make small adjustments to the turns ratio, so that the secondary voltage can be increased or reduced, if required, in order to meet the relevant statutory voltage variation requirements.Tap changing mechanisms may be 'off-load' or 'on-load' types.With off-load tap changers, the transformer must be de-energised before the tap-changing mechanism is altered, as the mechanism breaks the connection to the windings as it is changed.With on-load tap changers, the mechanism is adjusted (usually automatically, when required) with the transformer energised and supplying load. The mechanism is installed on the high-voltage side of the transformer (regardless of whether it is a step up or step down transformer) because the high-voltage windings carry the lower current, allowing smaller contacts to be used. On-load tap changers use a 'make-before-break' arrangement, so that the windings are never disconnected when the mechanism changes its tap setting.
What is off load tap change?
Tap changer is a device that is used to change the secondary voltage on transformers. It is normally on the HV winding of the transformer. Off load tap changer is designed to change the taps only when the transformer is not charged, while on load tap changer is capable of changing the tap on load too.
Why tapping is necessary in a transformer?
Taps are connections to the (usually) high-voltage winding of a transformer which enables minor changes to the turns-ratio to be made in order to make minor changes to the secondary voltage to compensate, where necessary, to a fall in terminal voltage below the regulatory allowance.There are two types of tap-changing mechanism, 'off-load' and 'on-load'.Off-load tap-changing mechanisms require the transformer to be isolated before its tap settings can be adjusted, and is normally the case with smaller distribution transformers.On-load tap-changing can be performed with the transformer supplying its load, usually automatically, in response to changes in its secondary voltage. On-load tap changing mechanisms have a 'make before break' switching arrangement, to ensure that the transformer windings are not open circuited during the operation of tap changing.
Why there is a need to disconnect transformer while using off-load tap changer?
Changing off-load tap changers requires opening up the transformer, draining (at least some) oil, and manually changing electrical connections. None of these things can be done while the transformer is hot.
What would an off load transformer tap changer be used for?
to inreases or decreases n. of turns of a transformerAnswerAn 'off-load' tap changer is a tap-changing mechanism that can only be used when the transformer is disconnected, as opposed to an 'on-load' tap-changing mechanism that can operate when the transformer is energised and on load.Tap changing is performed to slightly change the turns ratio of a transformer in order to keep the secondary voltage within the statutory limits (e.g. in the UK, 230 V +10% -6%) should there be a substantial change in load.
Difference between off load transformer and on load transformer?
Hope this helpsAn "OFF-Load tap transformer" can only have it's tap adjusted when it is De-energized,while the "On-Load tap transformer" can adjust its tap under load conditions.Kind RegardsHammad KhanUniversity of Western AustraliaAnswerAn 'off load' transformer is one whose secondary is open circuited, and not supplying a load. An 'on load' (not 'load') transformer is one that is connected to a load.
How does on load tap changers operate?
On-load tap-changers are operated by an electric motor, often by driving a flywheel mechanism. The operation of the tap-changer is controlled by an AVR (automatic voltage regulator) which monitors the transformer's secondary voltage.
Is an on-load tap changer considered as a resistor?
No. All a tap changer (whether 'off-load' or 'on-load') does is to make minor changes to the turns-ratio of a transformer.
What is the problem of operating a on-load furnace transformer with center tap?
What is the problem of operating a on-load furnace transformer with center tap
What is the difference between off load tap changer and on load tap changer?
An on-load tap-changer must not break the supply to the transformer's windings while the transformer is on load. So it has a 'make-before-break' arrangement with its contacts -i.e. one contact moves to the second tap setting, before the second contact moves away from the first tap setting, while a reactor balances the load currents when the contacts are on different tap settings. An on-load tap changer is motor-driven, and can be operated automatically or manually.An off-load tap-changer does not require a make-before-break arrangement, because it is designed to be operated when the transformer is disconnected.
What is on load tap chenger?
A tap changer is used to vary the turns ration between the windings of a transformer to make minor changes to the secondary voltage. An on-load tap changer enables the turns ratio to be altered without disconnecting the transformer. An off-load tap changer requires the transformer to be temporarily diconnected. On-load tap changers are installed on the high-voltage side of the transformer, where the current is lower.
What is no load tap changing in transformer?
It changes the tap while it is operation (hence "on load"). This allows real-time voltage regulation for the transformer secondary (as load picks up, causing the voltage to sag, the LTC can tap up, increasing the voltage).
What main by OCTC and OLTC in the transformer?
OCTC means off circuit tap changer (off load tap changer) and OLTC means on load tap changer. in octc we can change the tap position while the transformer is in off condition only. we can not change the tap position of octc in charged condtion of the transformer. the tap position of octc can be change in deenrgise condion of transformer only means if you nwant to chang the tap position firstly you will have to deenrgise the power transformer then you can change the tap position of octc.while in oltc we can change the tap position of OLTC in charged condition of power transformer. This is the basic diffirence between OCTC and OLTC.generally the OCTC used in single phase generating transformer (G.T.Power Transformer) and OLTC used in three phase powwer transformers like standby transformer and auto transformer in power plants and switch yards. for any other question please mail me at (ashu_uit2007@yahoo.co.in )
