Unit-11 Protection for Instrumentation in Hazardous Areas

Atmosphere where a cloud of combustible dust in the air during normal operation falls in Zone?

• Zone 1

• Zone 0

• Zone 21

• zone 2

Which electrical principle does a transformer use?

• EMI

• Self-Induction

• Mutual Induction

• Faradays Cage

What is the input part of this symbol?

• Earth Leakage Relay

• Inductor

• Switch

• capacitor

Which one of these is a limitation of a single-phase supply?

• Can't be stepped up.

• Normally limited to 230V / 240V

• Limited to 100 V

• The machines supplied are lighter but less efficient.

Which one is electro - mechanical switch?

• Transistor

• Inductor

• LED

• Relay

What hazardous areas classification would the zone marked up "C" on the diagram fall into?

• Zone 1

• Non-Hazardous Area

• Zone 2

• Zone 0

What hazardous areas classification would the zone marked up "A" on the diagram fall into?

• Zone 2

• Zone 1

• Non-Hazardous Area

• zone 0

Which Zones are used to identify / used for the Area Classification of Gas, Mists and Vapor’s

• Zones 20 & 21

• Zones 20, 21 and 22

• Zones 0, 1, 2, 20, 21 and 22

• Zones 0, 1 and 2

Which of the following descriptions describe a hazardous area zone classification 1?

• Explosive gas-air mixture is not likely to exist.

• Explosive gas-air mixture, likely occur in normal operation.

• Safe area no gas expected.

• Explosive gas-air mixture continuously present for long time

Which of the Gas Groups is applied to Mines.

• Group I

• Group IIC

• Group II

• Group IIIb