KNSS Oct.29.2014

Answer to Answer to Answer to Answer to Question from BQuestion from BQuestion from BQuestion from Bidderidderidderidder

andandandand Changing PurchaserChanging PurchaserChanging PurchaserChanging Purchasers Specifications Specifications Specifications Specification

Q1. What is the meaning of 2E or 3E relay for combination in the Switchgear Accessories?

A1. 2E and 3E-relay are usually used to protect the motor. (For detail of 2E and 3E relay, please visit

OMRON web site)

A2. If in the incoming 20kV we are using VCB only instead of VCB + DS, is it acceptable?

Q2. Not Acceptable.

Note) Single line diagram attached TPS is only for reference. Detail single line diagram shall be

proposed by bidder considering safety and maintenance.

Q3. In the 25 MVA Transformer accessories, as per our knowledge Sudden Pressure Detector is

Pressure Relief Device (PRD). Could you please confirm the same?

A3. Sudden pressure detector and Pressure relief device are different accessories.

Sudden pressure detector, or sudden pressure relay, detects sudden increase in gas pressure in a

transformer which would be caused by an internal arc.

Pressure relief device, or pressure relief vent, pressure relief valve, is the element to prevent

heavy damage of the tank in case of sudden increase of the internal pressure.

Note) In our GTS (General Technical Specification), it is specified that Pressure relief vent, (or

pressure relief valve, pressure relief device) is equipped only for shielded tank type transformer.

However, Pressure relief vent or equivalent devices shall be equipped to 25MVA transformers.

(Changing the Purchasers Specification)

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