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Routine Field Testing

Routine  field testing of the electrical equipment is intended to enable maintenance personal to determine,
without laboratory conditions  or complicated equipment, that a particular electrical equipment is able to
perform its basic circuit functions.

The following constitutes a guide to tests that might be performed during routine maintenance.

1.

Insulation Resistance Test

Extreme  atmospheres  and conditions may reduce the dielectric withstandability of any insulating
material. An instrument commonly known as "megger" is used to perform this test.

The  voltage recommended for this test should be at least 50 percent greater than the circuit rating;
however, a minimum of 500 volts is permissible. Tests should be made  between phases of
opposite  polarity as well as from current carrying parts of the circuit protective device to ground.
Also,  a test should be made between the line-and-load terminals with the circuit protective device
in the "OFF" position.

Resistance values below one megaohm are considered  unsafe  and  should be investigated for
possible contamination on the surfaces.

NOTE:  

For  individual  circuit  protective device's resistance readings, load and line conductors

should be disconnected. If not disconnected, the test measurements will also include the
characteristics of the attached circuits.

A  temperature  and humidity reading are recommended and recorded during the testing
period.

Insulation  resistivity  is  markedly effected by temperature and humidity conditions. Based
condition of one (1) megaohm per kV assumes a 20°C wet bulb reading. The following table shall
be used to adjust readings to the 20°C constant.

                 TABLE OF TEMPERATURE CORRECTION FACTORS

Temp (°C)

Motors

Transformers

Oil filled

Cables

PVC 90

XLPE

0

0.40

0.25

0.22

0.41

5

0.50

0.36

0.37

0.54

10

0.63

0.50

0.58

0.72

15

0.81

0.74

1.00

0.96

20

1.00

1.00

1.53

1.28

25

1.25

1.4

2.48

1.70

30

1.58

1.98

4.03

2.26

35

2.00

2.80

6.53

3.01

40

2.50

3.93

10.70

3.99

45

3.15

5.60

17.10

5.30

50

3.98

7.83

27.85

7.04

55

5.00

11.20

45.00

9.35

60

6.30

15.85

73.00

12.40

2.

Connection Test

Connections to the circuit protective device should be inspected to determine that  a proper
electrical  joint  is present. If overheating in these connections is evident by discoloration or signs
of arcing, the connections should be removed and the connecting surfaces clean  before re-

Summary of Contents for SAHARA 1000

Page 1: ...ipment ABB Electrical Industries Co Ltd Kingdom of Saudi Arabia ABB SAHARA Series Compact Substation OPERATING INSTRUCTIONS MODELS 24kV 36kV SAHARA 500 SAHARA MAX 1 SAHARA 1000 SAHARA MAX 2 SAHARA 1600 SAHARA 2000 SAHARA 3000 ...

Page 2: ...cal Inspection 7 MAINTENANCE AND PERIODIC INSPECTION 7 Bolt Tightness 7 Inspection and Testing 7 Routine Field Testing 8 1 Insulation Resistance Test 8 2 Connection Test 9 3 Mechanical Operation 9 TRANSFORMER MAINTENANCE 9 Inspection during operation 9 Maintenance during operation 9 Inspection and Measures to be taken during downtime 9 Inspection of oil leaks and precautions to be taken 9 Inspecti...

Page 3: ...rtance of care in Site selection and design embodying features that provide adequate ventilation protection and security and which have taken account of appropriate fire moisture and explosion hazards Jointing Earthing Selection and setting of electrical protection in primary and secondary against overload overvoltage and short circuit Carrying out regular inspection and electrical and mechanical ...

Page 4: ...ion has not sustained any damage during transportation Immediately upon receipt of the Package Compact Substation examine them to determine if any damage or loss was sustained during transit If abuse or rough handling is evident file a damage claim with carrier and promptly notify the nearest ABB office ABB ELECTRICAL INDUSTRIES CO LTD is not responsible for damage of goods after delivery to the c...

Page 5: ... LIFT OR MOVE A TRANSFORMER OR PACKAGE COMPACT SUBSTATION WITHOUT ADEQUATE EQUIPMENT AND PRECAUTIONS 2 TERMINALS ARE FOR ELECTRICAL LOADING ONLY 3 DO NOT MAKE ANY CONNECTIONS THAT ARE NOT AUTHORIZED BY THE NAMEPLATE OR CONNECTION DIAGRAMS 4 DO NOT ENERGIZE THE SUBSTATION WITHOUT PROPERLY MADE GROUND OR EARTH CONNECTIONS 5 DO NOT ATTEMPT TO CHANGE THE TAP SETTINGS WHILE THE TRANSFORMER IS ENERGIZED...

Page 6: ...due stress on the terminals Conductors should be securely fastened in place and adequately supported with allowances for expansion and contraction FINAL INSPECTION PRIOR TO ENERGIZATION After the Package Compact Substation has been found to be in good condition and the protective equipment is operational the substation may be connected to the network However it is recommended that the transformer ...

Page 7: ...awings and previous test records before starting activity Scrutinize maintenance instructions given for the equipment to be maintained Maintenance information is given in the Operation and Maintenance Manual for each type of equipment The main dangers of such process are Inaccessible lubrication points greased for life cannot be lubricated and may seize up Areas not lubricated may be subject to co...

Page 8: ...estigated for possible contamination on the surfaces NOTE For individual circuit protective device s resistance readings load and line conductors should be disconnected If not disconnected the test measurements will also include the characteristics of the attached circuits A temperature and humidity reading are recommended and recorded during the testing period Insulation resistivity is markedly e...

Page 9: ...ntenance measures can be carried out which can not normally be performed during operation Before starting maintenance work the transformer has to be disconnected from the network and earthed or grounded When the disconnector has been opened one has to see to that they stay open and before grounding or earthing one has to test that they are voltage free i e with a voltage tester Inspection of oil l...

Page 10: ...ten of milliamperes With the same voltage reading the current taken by other phases can be measured The excitation currents of different phases should be approximately the same magnitude In a damage phase the current can rise to tens of amperes thus the regulating transformer has to be protected by a suitable fuse 4 DC resistance of windings A satisfactory large DC source and an accurate resistanc...

Page 11: ...energy may be different for different fuse types as well as the selection tables and protection characteristics It is compulsory to use the same type of fuse links in all phases type rated current The disconnector cannot be closed before the fuse links are changed Note According to IEC Publication 282 1 all 3 fuse links should be replaced even if only 1 or 2 of the fuse links in the three phase sy...

Page 12: ...uring periodic checks established the best fixed periods for maintenance work It is also advisable to refer to the following rules The circuit breakers that operate rarely or which remain closed or open for long periods must be activated once in a while to prevent a tendency to jam which might cause reductions in the closing or opening speed During service circuit breaker must be visually check fr...

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