Switchgear Protections Set 1

solid state ✘ thermal ✘ electromagnetic ✘ all above ✔

no ageing effect ✘ high speed of operation ✘ high rupturing capacity ✘ all of the above ✔

heavy loads ✘ internal short-circuits ✘ external short-circuits ✘ all of the above ✔

Lightning arresters ✘ Relays ✘ Step-down transformer ✘ Switchgear ✔

5 to 20 sec ✘ 5 to 10 sec ✘ 20 to 30 sec ✘ none of the above ✔

a capackive reactance ✘ an inductive reactance ✘ a resistance increasing with voltage rise across the arc ✘ a resistance decreasing with voltage rise across the arc ✔

in series with circuit ✘ in parallel with circuit ✘ either in series or in parallel with circuit ✘ none of the above ✔

zero ✘ infinity ✘ unity ✘ none of the above ✔

20 A ✘ 50 A ✘ 100 A ✘ 200 A ✔

2 ✘ 4 ✘ 6 ✘ 10 ✔