Which Relay Is Used In Transformer?

What is a transformer relay?

Transformer Relays provide primary protection, control, and back-up protection of transformers, including current differential, restricted ground differential, and overcurrent protection..

What is BDV test in transformer?

The dielectric strength of transformer oil is also known as the breakdown voltage (BDV) of transformer oil. Breakdown voltage is measured by observing at what voltage, sparking strands between two electrodes immersed in the oil, separated by a specific gap.

Where Buchholz relay is used?

Buchholz relay is a safety device which is generally used in large oil immersed transformers (rated more than 500 kVA). It is a type of oil and gas actuated protection relay.

What is BDV value?

BDV test means Breakdown Voltage Test. … Dielectric strength means the maximum capacity to withstand voltage of insulating oil. This test shows the dielectric strength of Transformer oil. In transformer oil has mainly two purposes, first for insulation, second as cooling of Transformer core and other winding.

Why Buchholz relay is used in transformer?

What is Buchholz Relay? … The Buchholz relay purpose is to give the protection to a transformer from the different faults happening in the transformer like the Short circuit, inter-turn, core, incipient, etc. This relay will sense these faults and shuts the alarm circuit.

What is CT and PT transformer?

Difference Between Current Transformer (CT) & Potential Transformer (PT) … One of the major difference between them is that the current transformer converts the high value of current into low value whereas the potential or voltage transformer converts the high value of voltages into low voltage.

What is name of transformer oil?

Mineral oil and Synthetic oil are the majorly used transformer oil. These are the petroleum products, like Naphthenic based transformer oil and Paraffinic based transformer oil.

Why the transformer rating is in kVA?

The copper and iron are the two type of losses occur in the transformer. The copper loss depends on the current (ampere) flows through the windings of the transformer while the iron loss depends on the voltage (volts). i.e., the rating of the transformer is in kVA.

Which relay is used in transformer protection?

thermal overload relayThe protection of a transformer against the overloads is performed by a dedicated protection usually called thermal overload relay. This type of protection simulates the temperature of the transformer’s windings. The simulation is based on the measure of the current and on the thermal time constant of the transformer.

What is WTI and OTI?

The WTI means winding temperature Indicator and OTI means Oil Temperature Indicator which indicates the winding temperature & oil temperature of the transformer and operates the alarm, trip, and cooler control contacts. This instrument operates on the principle of thermal imaging and it is not an actual measurement.

What is the Colour of transformer oil?

Generally, oil that is yellow, orange, or even somewhat red in color is fresher and will work as intended. As oil ages, it transforms to a brown or black color and its efficacy diminishes.

Who invented Buchholz relay?

Max BuchholzThe relay was first developed by Max Buchholz (1875–1956) in 1921.

How many relays does a transformer have?

Relays for Transformer ProtectionSLVoltage Ratio and Capacity of TransformerRelays on LV Side8220/33 KV, 31.5MVA & 50MVA 220/132KV, 100 MVA3 nos O/L Relay 1 no Directional E/L Relay9400/220KV 315MVA3 nos Directional O/L Relay (with dir.highset) 1 no Directional E/L relay. Restricted E/F relay7 more rows•Jun 8, 2019

What are the two types of relays?

There are different types of polarized relays depends on the magnetic circuit configuration. The two most popular types of these relays include differential and bridge type relays. In differential magnetic system, the difference of two fluxes of permanent magnet acts on the armature.

What is PSM relay?

Since currents are measured through current transformer, both Iref and I should be referred to either primary or secondary of the CT. This ratio abs(I / Iref) is called the Plug Setting Multiplier (PSM). The value of PSM indicates the severity of the fault as seen by the relay.

What is working principle of Buchholz relay?

Buchholz Relay Working Principle It is mechanically actuated. Whenever there will be a minor internal fault in the transformer such as an insulation fault between turns, break down of core of the transformer, core heating, the insulating transformer oil will be decomposed in different hydrocarbon gases, CO2 and CO.

What is meant by Buchholz relay?

Definition: The Buchholz relay protects the transformer from internal faults. It is the gas actuated relay. The Buchholz relay is placed between the main tank and the conservator. Such type of relay is used in the transformer having the rating higher than 500KVA.

What is PRV in transformer?

Transformer pressure relief device valve for liquid-immersed transformers open in case of an internal fault and guarantee that the occured overpressure can properly release. The pressure relief valves are tested for operating pressure. …