Solid Earthing is employed for voltages

A. Upto 11kv
B. Upto 33 kv
C. Upto 66kv
D. Upto 132 kv

Answer: B. Upto 33 kv

Explanation:

What is Solid Earthing?

When the neutral point of a 3-phase system (e.g. 3- phase generator, 3-phase transformer etc.) is directly connected to earth (i.e. soil) through a wire of negligible resistance and reactance, it is called solid grounding or effective grounding.

Advantages

• The solid grounding of neutral point has the following advantages:
• The neutral is effectively held at earth potential.
• no arcing ground phenomenon or over-voltage conditions can occur.
• there is a saving in the cost of equipment.
• It becomes easier to protect the system from earth faults which frequently occur on the system. When there is an earth fault on any phase of the system, large fault current flows between the fault point and the grounded neutral. This permits the easy operation of earth fault relay.

Disadvantages

• The following are the disadvantages of solid grounding :
• Since most of the faults on an overhead system are phase to earth faults, the system has to bear a large number of severe shocks. This causes the system to become unstable.
• The solid grounding results in heavy earth fault currents. Since the fault has to be cleared by the circuit breakers, the heavy earth fault currents may cause the burning of circuit breaker contacts.
• The increased earth fault current results in greater interference in the neighboring communication lines.

Applications

• Solid grounding is usually employed where the circuit impedance is sufficiently high so as to keep the earth fault current within safe limits. 
• This system of grounding is used for voltages up to 33 kV with total power capacity not exceeding 5000 kVA.

Power System MCQs With Explanation 

 

• The advantages of high transmission voltage are
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• In which of the following transmission lines capacitance effect is negligible?
• The distribution constant of the transmission line is
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Transformer MCQs With Explanation 

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• The power transformer can be termed as a constant
• In a transformer, which of the following losses are zero?
• Which of the following Transformer can have a tap changer?
• If the supply frequency (f) of a transformer decreases, the effect of frequency on the transformer's secondary output voltage?
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• The efficiency of a power transformer is _____ at full load.
• In a transformer the relation between the input frequency and the output voltage on secondary winding is _____.
• In a current transformer, _____ winding is closed.
• A transformer is a _____ device.
• A step-down transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
• A step-up transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
• Transformer works on ______ principle.
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Synchronous Motor MCQs With Explanation 

• In 3 -Φ synchronous motor if one of the phases is short-circuited the motor will
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Induction Motor MCQs With Explanation 

• In a capacitor start and run the motor the function of the running capacitor in series with the auxiliary winding is to
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