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271.

Die sinking is

A.	The process of hardening of dies by sinking in quenching oil	B.	The local cooling of dies on the dia surface by pouring oil on the spot
C.	The process of cutting die impression	D.	The process of scrapping a die impression so that remaining metal may be retrieved for further use
E.	None of the above

272.

A time switch is

A.	A switch which operates for a fixed time only	B.	A switch which gets energised with time
C.	A 24 hour timing device used to open and close electric circuits according to time of day on a continually repeating schedule	D.	A switch with records timings of operation of a circuit
E.	None of the above

273.

The linear characteristics of valve is

A.	In which the length of valve is more than 10 times the width	B.	In which the longest parameter of valve is not less than 20 times the widest part of the valve
C.	In which the valve steam operates linearly	D.	One in which the flow is directly proportional to the valve lift
E.	None of the above

274.

The equal percentage characteristic of a valve is

A.	Uniform flow rate	B.	Flow rate proportional to valve lift
C.	Each increment of plug movement produces a change in flow which is proportional to the amount flowing before the change occurred	D.	The flow rate before the plug movement is equal to the flow rate after the movement
E.	Percentage increase in flow is equal to the percentage increase in lift

275.

The limitation of a pneumatically operated automatic control system

A.	is complexity of components	B.	is costly maintenance
C.	Suffers from the transmission lags and slow response	D.	None of the above
E.	All of the above

276.

A bleed type relay is generally used in

277.

The advantage of electronically operated automatic control system is

A.	Needs no maintenance	B.	Can be located in hazardous locations
C.	Does not cost much	D.	Does not require skilled service personnel
E.	No time lags, no transmission delays

278.

The limitation of electronically operated automatic control system is

A.	Considerable time lag	B.	Poor accuracy
C.	Serious effect of ambient conduction	D.	Complicated control response
E.	It requires eloborate protection in hazardous locations

279.

The advantage of mercury switch is

A.	No mechanical moving parts	B.	No open contacts
C.	Sealed from dirt and contamination	D.	Maintanance free
E.	All of the above

280.

Thermistors are

A.	Materials highly sensitive to temperature changes	B.	Used for measurement of thermal properties
C.	Semi-conductor materials having large negative coefficient of resistance	D.	Bimetallic strips used in thermometers
E.	Clad metals used in accurate measurement of temperature changes