What Causes Inefficiency and Power Loss in the Transformer?

Inefficiency and the power loss in a transformer is caused by three things:

A. Hysteresis loss: which is caused by the magnetic field created in the transformer’s primary, secondary and harmonic windings. 

B. Eddy current loss: or skin effect: which is caused by the high frequency current traveling on the outer edge of the conductor. 

C. Copper loss: which is caused by the power dissipated in the windings of a transformer. Copper loss is minimized by using as large conductors as possible in the windings. 

Note: A and B are fixed losses. C varies by  I²R. When the efficiency is computed the computation is done with 100% load.

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What are the types of protection of a power system?

Types of Protection:

1. Apparatus Protection

- Busbar Protection

- Motor Protection

- Generator Protection

- Transformer Protection

- Transmission Line Protection

2. System Protection

- Under-frequency Relays
- Out-of-Step Protection

- Islanding Systems
- Rate of Change of Frequency Relays

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Why do we need protection of a power system?

Electrical apparatus operates at various voltage levels and may be enclosed or placed in open. Under abnormal operating conditions protection is necessary for-

• Safety of electrical equipments.
• Safety of human personnel.

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Define measuring instrument and measurement system.

Measurement system: The procedure of measure a quantity is called the measurement system. 

Measuring instruments: The measuring instruments are used for measure the quantity. 

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Write down the methods of measurement and explain them.

The methods of measurements are classified into two categories- 

a) Direct methods and 

b) Indirect methods. 

Direct methods: In these methods, the unknown quantity is directly compared against a standard. The result is expressed as a numerical number and a unit. Direct methods are quite common for the measurement of physical quantities like length, mass and time. 

Indirect methods: These methods are apply in which measurement by direct method are not possible, flexible and practicable. This method includes always error in measurement.

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