If the OLTC is on the secondary, and the secondary voltage is high, the OLTC will tap down, which will lower the voltage. Typical range of OLTC is +/- 10%. The primary may also have multiple taps so the OLTC can be set at '0' under normal conditions.
oltc is situated on primary side of transformer because by primary side we can obtain fine voltage change by tapping with low current flow through it.
It means 'on-load tap changer' - I found a page in Wikipedia that explains it - see related link. Read the section titled 'Voltage considerations'
OLTC - INSTALLED IN THE PRIMARY SIDE OF A POWER TRANSFORMER TO SELECT OR ADJUST VOLTAGE. THE ADVANTAGE OF THIS IS FOR SOLVING THE VOLTAGE DROP ISSUES IN THE SECONDARY OUTPUT IN THE FARTHEST LOCATION. FOR EXAMPLE YOUR SECONDARY VOLTAGE REQUIREMENT IS 380 VOLTS AND YOU CAN ADJUST TO 400 VOLTS FOR LONG CABLE RUNS.
RTCC (Remote tap changer control) panel is one of the LT panel which has microcontroller, contactors, relays etc it senses the fluctuation in distribution voltage (input of Transformer) & give signal to OLTC to change the voltage(Output of the transformer) to set a value
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 )
OSR meance oil surge relay & it is used in x'mer OLTC . it is measured if any surge produce in oil then the give the signsl to relay panel for tripping of transformer
The TRANSFORMER PROTECTOR is a transformerexplosion and fire prevention system suitable for any type of oil-immersed transformer and including surrounding equipment such as the On Load Tap Changer (OLTC), Oil Cable Box (OCB), and Oil Bushing Cable Box (OBCB).
For carrying Short Circuit Test on Power Transformer Do the following: 1] Isolate the Power Transformer from service. 2] Remove HV/LV Jumps and Disconnect Neutral from Earth/Ground. 3] Short LV Phases by Cu/Al plate which could withstand short circuit current and connect these short circuited terminals to Neutral 4] Energise HV side by LV supply (440 3ph Supply) with OLTC tap position on Normal. 5] Measure Current in Neutral, LV line voltages, HV Volatage and HV Line Currents on various OLTC Tap position. Analysis: If Neutral current is near to zero transformer windings are OK If Neutral current is higher or equal to Line current between LV Phase one of the winding is Open.
For carrying Short Circuit Test on Power Transformer Do the following: 1] Isolate the Power Transformer from service. 2] Remove HV/LV Jumps and Disconnect Neutral from Earth/Ground. 3] Short LV Phases by Cu/Al plate which could withstand short circuit current and connect these short circuited terminals to Neutral 4] Energise HV side by LV supply (440 3ph Supply) with OLTC tap position on Normal. 5] Measure Current in Neutral, LV line voltages, HV Volatage and HV Line Currents on various OLTC Tap position. Analysis: If Neutral current is near to zero transformer windings are OK If Neutral current is higher or equal to Line current between LV Phase one of the winding is Open.
There are many types of protection relays used in transformers depend upon its construction, size, use etc. They are 1. Buchholz relay for incipient faults like short ciruit, winding temparature protection, oil temparature protection, oil level protection, oil pressure protection, Pressure relief valve (for oil filled transformers) 2. Differential protection 3. Thermal Protection 4. Earth fault protection 5. Over current protection 6. Over excitation protection(where OLTC is used) etc