Most of the questions here are concerned with the following topics:

MOTOR TESTS MEASUREMENTS

Give examples of tests done on motors.

The following are some important electric motor testing items:

Electric Motor Impulse Testing

Electric Motor Rotation Testing

Wound Rotor Motor Testing

Electric Motor Insulation Resistance Testing

The recommended off-line in-service electric motor tests are –

• Stator winding resistive imbalance
• Stator winding insulation resistance (Meg-Ohm checks)
• Polarization Index (PI)
• Step Voltage test
• Surge test

The recommended spare electric motor tests are –

• Stator winding resistive imbalance
• Stator winding insulation resistance (Meg-Ohm checks)
• Polarization Index (PI)
• Step Voltage test
• Surge test

The recommended new/refurbished electric motor tests are –

• Stator winding resistive imbalance
• Stator winding insulation resistance (Meg-Ohm checks)
• Polarization Index (PI)
• Step Voltage test
• Surge test.

PRESURE MEASUREMENTS

What Is Pressure?

Pressure Measurement Methods

There are three methods for measuring pressure: absolute, gauge, and differential.

Pressure Sensor Types

There are a variety of pressure sensor designs due to different measurement conditions, ranges, and materials used in construction of the sensor. Common pressure sensor types are bridge-based, amplified, and piezoelectric sensors. Pressure is measured by converting the physical phenomenon to an intermediate form, such as displacement, which can be measured by a transducer.

TRANSFORMER TESTS

Under Electrical Transformer

For confirming the specifications and performances of an electrical power transformer it has to go through numbers of testing procedures. Some tests are done at manufacturer premises before delivering the transformer. Mainly two types of transformer testing are done at manufacturer premises- type test of transformer and routine test of transformer. In addition to that some transformer tests are also carried out at the consumer site before commissioning and also periodically in regular & emergency basis throughout its service life.

Type of Transformer Testing

Tests done at factory

1. Type tests
2. Routine tests
3. Special tests

Tests done at site

1. Pre-commissioning tests
2. Periodic/condition monitoring tests
3. Emergency tests

Type tests of transformer includes

1. Transformer winding resistance measurement
2. Transformer ratio test.
3. Transformer vector group test.
4. Measurement of impedance voltage/short circuit impedance (principal tap) and load loss (Short circuit test).
5. Measurement of no load loss and current (Open circuit test).
6. Measurement of insulation resistance.
7. Dielectric tests of transformer.
8. Temperature rise test of transformer.
9. Tests on on-load tap-changer.
10. Vacuum tests on tank and radiators.

Routine tests of transformer include

1. Transformer winding resistance measurement.
2. Transformer ratio test.
3. Transformer vector group test.
4. Measurement of impedance voltage/short circuit impedance (principal tap) and load loss (Short circuit test).
5. Measurement of no load loss and current (Open circuit test)
6. Measurement of insulation resistance.
7. Dielectric tests of transformer.
8. Tests on on-load tap-changer.
9. Oil pressure test on transformer to check against leakages past joints and gaskets.

Special Tests of transformer include

1. Dielectric tests.
2. Measurement of zero-sequence impedance of three-phase transformers
3. Short-circuit test.
4. Measurement of acoustic noise level.
5. Measurement of the harmonics of the no-load current.
6. Measurement of the power taken by the fans and oil pumps.
7. Tests on bought out components / accessories such as buchhloz relay, temperature indicators, pressure relief devices, oil preservation system etc.

Vector Group Test of Transformer

In three phase transformer, it is essential to carry out a vector group test of transformer. Proper vector grouping in a transformer is an essential criteria for parallel operation of transformers.

Insulation Resistance Test or Megger Test of Transformer

Insulation resistance test of transformer is essential type test. This test is carried out to ensure the healthiness of overall insulation system of an electrical power transformer.

What is the procedure of Insulation Resistance Test of Transformer?

Dielectric Tests of Transformer

Dielectric tests of transformer is one kind of insulation test.

Induced Voltage Test of Transformer

The induced voltage test of transformer is intended to check the inter turn and line end insulation as well as main insulation to earth and between windings-

Temperature Rise Test of Transformer

Temperature rise test of transformer is included in type test of transformer. In this test we check whether the temperature rising limit of the transformer winding and oil as per specification or not .Type tests are tests made on a transformer which is representative of other transformers to demonstrate that they comply with specified requirements not covered by routine tests:

You will also need to have a depth of knowledge on Programmable Logic Controllers and SCADA and how they applied in the manufacturing sector.

 

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