SOW NETA Tables and Appendix.pdf

Tables

TABLE 100.

Insulation Resistance Test Values Electrical Apparatus and Systems

Nominal Rating of Equipment in Volts

Minimum Test Voltage, DC

Recommended Minimum Insulation Resistance in

Megohms 250 500 25 600 1,000 100

1,000 1,000 100 2,500 1,000 500 5,000 2,500 1,000 8,000 2,500 2,000

15,000 2,500 5,000 25,000 5,000 20,000

34,500 and above 15,000 100,000

In the absence of consensus standards dealing with insulation-resistance tests, the Standards Review Council suggests the above representative values.

See Table 100.14 for temperature correction factors.

Test results are dependent on the temperature of the insulating material and the humidity of the surrounding environment at the time of the test.

Insulation-resistance test data may be used to establish a trending pattern. Deviations from the baseline information permit evaluation of the insulation.

ATS-2007

Switchgear Withstand Test Voltages

Type of Switchgear

Rated Maximum Voltage (kV) (rms)

Maximum Test Voltage kV

AC DC

Low-Voltage Power Circuit Breaker

Switchgear

.254/.508/.635

1.6

2.3

Metal-Clad Switchgear

4.76 14 20

8.25 27 37

15.0 27 37

27.0 45 †

38.0 60 †

Station-Type Cubicle

Switchgear

15.5 37 †

38.0 60 †

72.5 120 †

Metal Enclosed Interrupter Switchgear

4.76 14 20

8.25 19 27

15.0 27 37

15.5 37 52

25.8 45 †

38.0 60 †

Derived from ANSI/IEEE C37.20.1-1993, Paragraph 5.5, Standard for Metal-Enclosed Low-Voltage Power Circuit- Breaker Switchgear, C37.20.2-1993, Paragraph 5.5, Standard for Metal-Clad and Station-Type Cubicle Switchgear and C37.20.3-1987 (R1992), Paragraph 5.5, Standard for Metal-Enclosed Interrupter Switchgear, and includes 0.75 multiplier with fraction rounded down.

The column headed “DC” is given as a reference only for those using dc tests to verify the integrity of connected cable installations without disconnecting the cables from the switchgear. It represents values believed to be appropriate and approximately equivalent to the corresponding power frequency withstand test values specified for voltage rating of switchgear. The presence of this column in no way implies any requirement for a dc withstand test on ac equipment or that a dc withstand test represents an acceptable alternative to the low-frequency withstand tests specified in these specifications, either for design tests, production tests, conformance tests, or field tests. When making dc tests, the voltage should be raised to the test value in discrete steps and held for a period of one minute.

† Because of the variable voltage distribution encountered when making dc withstand tests, the manufacturer should be contacted for recommendations before applying dc withstand tests to the switchgear. Voltage transformers above 34.5 kV should be disconnected when testing with dc. Refer to ANSI/IEEE C57.13-1993 (IEEE Standard Requirements for Instrument Transformers) paragraph 8.8.2.

Recommended Dissipation Factor/Power Factor at 20° C Liquid-Filled Transformers, Regulators, and Reactors

Acceptance Test Values

Oil, Silicone, and Less-Flammable Hydrocarbon Maximum Value (Percent) New Power Transformers and Reactors 0.5% New Distribution Transformers and Regulators 1.0% Remanufactured Power Transformers and Reactors 1.0% Remanufactured Distribution Transformers and Regulators 1.5%

In the absence of consensus standards dealing with transformer dissipation-factor or power-factor values, the NETA Standards Review Council suggests the above representative values.

Insulating Fluid Limits

Table 100.4.1 Test Limits for New Insulating Oil Received in New Equipment

Mineral Oil

Test

ASTM

Method

≤ 69 kV and Below

>69 kV - < 230 kV

>230 kV - < 345 kV

>345 kV and Above

Dielectric breakdown, kV minimum D877 30 30 30 kV minimum @ 1mm (0.04") gap

D1816 kV minimum @ 2 mm (0.08") gap

Interfacial tension mN/m minimum

D971 or D2285 38 38 38 38

Neutralization number, mg KOH/g maximum D974 0.015 0.015 0.015 0.015

Water content, ppm maximum D1533 20 10 10 10

Power factor at 25° C, % D924 0.05 0.05 0.05 0.05 Power factor at 100° C, % D924 0.40 0.40 0.30 0.30 Color D1500 1.0 1.0 1.0 0.5 Visual condition D1524 Bright and clear Bright and clear Bright and clear Bright and clear

ANSI/IEEE C57.106-2002, Guide for Acceptance and Maintenance of Insulating Oil in Equipment, Tables 1, 2, and 3.

Table 100.4.2 Test Limits for Silicone Insulating Liquid in New Transformers

Test ASTM Method Acceptable Values Dielectric breakdown, kV minimum D877 30 Visual D2129 clear, free of particles Water content, ppm maximum D1533 50 Dissipation/power factor, 60 hertz, % max. @ 25° C

D924 0.1

Viscosity, cSt @ 25° C D445 47.5 – 52.5 Fire point, ° C, minimum D92 340 Neutralization number, mg KOH/g max.

D974 0.01

ANSI/IEEE C57.111-1989 (R1995), Guide for Acceptance of Silicone Insulating Fluid and Its Maintenance in Transformers, Table 2.

TABLE 100.4 (continued)

Insulating Fluid Limits

ANSI/IEEE C57.121-1998, IEEE Guide for Acceptance and Maintenance of Less Flammable Hydrocarbon Fluid in Transformers, Table 3.

The test limits shown in this table apply to less-flammable hydrocarbon fluids as a class. Specific typical values for each brand of fluid should be obtained from each fluid manufacturer.

a. If the purpose of the HMWH installation is to comply with the NFPA 70 National Electrical Code, this value is the minimum for compliance with NEC Article 450.23.

Table 100.4.3 Typical Values for Less-Flammable Hydrocarbon Insulating Liquid

Received in New Equipment

ASTM

Method

Test

Results

Minimum Maximum

Dielectric breakdown voltage for 0.08 in gap, kV

40 34.5 kV class and below ----- 50 Above 34.5 kV class

60 Desirable

Dielectric breakdown voltage for 0.04 in gap kV

20 34.5 kV class and below ----- 25 Above 34.5 kV class

30 Desirable D974 Neutralization number, mg KOH/g ----- 0.03 D877 Dielectric breakdown voltage Kv 30 -----

D924

AC loss characteristic (dissipation factor), % 25° C 100° C

0.1

D1533B Water content, ppm ----- 25 D1524 Condition-visual Clear D92 Flash point (° C) 275 ----- D92 Fire point (° C) 300a ----- D971 Interfacial tension, mN/m, 25° C 38 ----- D445 Kinematic viscosity, mm2/s, (cSt), 40° C 1.0 X 102 (100) 1.3 X 102 (130) D1500 Color ----- L2.5

TABLE 100.5

Transformer Insulation Resistance Acceptance Testing

Transformer Coil

Rating Type in Volts

Minimum DC Test

Voltage

Recommended Minimum Insulation Resistance in Megohms

Liquid Filled Dry 0 - 600 1000 100 500 601 - 5000 2500 1000 5000 Greater than 5000 5000 5000 25000

In the absence of consensus standards, the NETA Standards Review Council suggests the above representative values.

See Table 100.14 for temperature correction factors.

NOTE: Since insulation resistance depends on insulation rating (kV) and winding capacity (kVA), values obtained should be compared to manufacturer’s published data.

TABLE 100.6

Medium-Voltage Cables

Table 100.6.1 DC Test Voltages

Rated Voltage Phase-to-Phase kV

Conductor Size AWG or kcmil (mm)

Nominal

Insulation Thickness mils (mm)

Maximum DC Field Test Voltages, kV

During/After Installation

100% Insulation

Level

133% Insulation

Level

100% Insulation

Level

133% Insulation

Level

5 8-1000 (8.4-507) Above 1000 (507)

90 (2.29) 140 (3.56)

115 (2.92) 140 (3.56)

8 6-1000 (13.3-507) Above 1000 (507)

115 (2.92) 175 (4.45)

140 (3.56) 175 (4.45)

15 2-1000 (33.6-507) Above 1000 (507)

175 (4.45) 220 (5.59)

220 (5.59) 220 (5.59)

25 1-2000 (42.4-1013) 260 (6.60) 320 (8.13) 80 96 28 1-2000 (42.4-1013) 280 (7.11) 345 (8.76) 84 100 35 1/0-2000 (53.5-1013) 345 (8.76) 420 (10.7) 100 124 46 4/0-2000 (107.2-1013) 445 (11.3) 580 (14.7) 132 172 69 4/0-2000 (107.2-1013) 650 195

Tables derived from ANSI/ICEA S 93-639/NEMA WC 74-2000, 5-46 kV Shielded Power Cable for Use in the Transmission and Distribution of Electric Energy; ANSI/ICEA S-94-649-2000, Standard for Concentric Neutral Cables Rated 5,000 - 46,000 Volts; ANSI/ICEA S-97-682-2000, Standard for Utility Shielded Power Cables Rated 5,000 - 46,000 Volts; and The Okonite Company, High-Voltage Proof Testing.

DC test voltages are applied to discover gross problems such as incorrectly installed accessories or mechanical damage.

The dc field test voltages listed above are intended for cable designed in accordance with ICEA specifications. When older cables or other types/classes of cables or accessories are connected to the system, voltages lower than those shown may be necessary. Consult the manufacturers of the cables and accessories before applying the test voltage.

TABLE 100.6 (continued)

Table 100.6.2 AC Test Voltages

Conductor Size AWG or kcmil

Nominal Insulation Thickness

Mils (mm)

AC Test Voltage, kV

100% Insulation

Level

133%

100%

133%

Level

5 kV 8-1000 1001-3000

90 (2.29) 140 (3.56)

115 (2.92) 140 (3.56)

8 kV 6-1000 1001-3000

115 (2.92) 175 (4.45)

140 (3.56) 175 (4.45)

15 kV 2-1000 1001-3000

175 (4.45) 220 (5.59)

220 (5.59) 220 (5.59)

25 kV 1-3000 260 (6.60) 320 (8.13) 52 64

28 kV 1-3000 280 (7.11) 345 (8.76) 56 69

35 kV 1/0-3000 345 (8.76) 420 (10.7) 69 84

46 kV 4/0-3000 445 (11.3) 580 (14.7) 89 116

Tables derived from ANSI/ICEA S 93-639/NEMA WC 74-2000, 5-46 kV Shielded Power Cable for Use in the Transmission and Distribution of Electric Energy; ANSI/ICEA S-94-649-2000, Standard for Concentric Neutral Cables Rated 5,000 - 46,000 Volts; ANSI/ICEA S-97-682-2000, Standard for Utility Shielded Power Cables Rated 5,000 - 46,000 Volts.

All ac voltages are rms values.

TABLE 100.6 (continued)

Table 100.6.3 Partial Discharge Requirements for Semiconducting Coating and Tape Designs Only

Rated Circuit Voltage

Volts

Minimum Partial Discharge Extinction Level, kV

100% Insulation Level 133% Insulation Level 2001-5000 4 5 5001-8000 6 8

8001-15000 11 15

In the absence of consensus standards the NETA Standards Review Council suggests the above representative values.

ANSI/ICEA S 93-639/NEMA WC 74-2000, 5-46 kV Shielded Power Cable for Use in the Transmission and Distribution of Electric Energy.

Table 100.6.4 Very Low Frequency Testing Levels

0.1 Hz Test Voltage (rms)

System Voltage Phase-to-Phase

(kV) (rms)

Proof Phase-to-Ground

(kV) (rms)

5 10

15 22

25 33

35 47

In the absence of consensus standards the NETA Standards Review Council suggests the above representative values.

Inverse Time Trip Test at 300% of Rated Continuous Current of Circuit Breaker

Molded-Case Circuit Breakers

Range of Rated Continuous

Current (Amperes)

Maximum Trip Time in Seconds For Each Maximum Frame Ratinga

< 250 V 251 – 600V 0-30 50 70 31-50 80 100

51-100 140 160 101-150 200 250 151-225 230 275 226-400 300 350 401-600 - - - - - 450 601-800 - - - - - 500

801-1000 - - - - - 600 1001 – 1200 - - - - - 700 1201-1600 - - - - - 775 1601-2000 - - - - - 800 2001-2500 - - - - - 850 2501-5000 - - - - - 900

6000 - - - - - 1000

Derived from Table 5-3, NEMA Standard AB 4-1996, Guidelines for Inspection and Preventive Maintenance of Molded- Case Circuit Breakers Used in Commercial and Industrial Applications.

a. Trip times may be substantially longer for integrally-fused circuit breakers if tested with the fuses replaced by solid links (shorting bars).

Instantaneous Trip Tolerances for Field Testing of Circuit Breakers

Tolerances of Manufacturer’s Published Trip Range

Breaker Type Tolerance of Settings High Side Low Side

Adjustable +40% -30%

Nonadjustable - - - - - +25% -25%

Reproduction of Table 5-4 from NEMA publication AB4-1996.

For circuit breakers with nonadjustable instantaneous trips, tolerances apply to the manufacturer’s published trip range, i.e., +40 percent on high side, -30 percent on low side.

Instrument Transformer Dielectric Tests Field Acceptance

Nominal System

Voltage (kV)

BIL

(kV)

Periodic Dielectric Withstand Test Field Test Voltage (kV)

AC DC*

0.60 10 3.0 4

1.20 30 7.5 10

2.40 45 11.25 15

5.00 60 14.25 19

8.70 75 19.5 26

15.00 95 25.5 34

15.00 110 25.5 34

25.00 125 30.0 40

25.00 150 37.5 50

34.50 200 52.5 70

46.00 250 71.2 +

69.00 350 105 +

115.00 450 138 +

115.00 550 172 +

138.00 650 206 +

161.00 750 243 +

230.00 900 296 +

230.00 1050 345 +

345.00 1300 431 +

500.00 1675 562 +

500.00 1800 600 +

765.00 2050 690 +

Table 100.9 is derived from Paragraph 8.8.2 and Tables 2 of ANSI/IEEE C57.13-1993, Standard Requirements for Instrument Transformers.

+ Periodic dc potential tests are not recommended for transformers rated higher than 34.5 kV.

* DC potential tests are not recommended for transformers rated higher than 200 kV BIL. DC tests may prove beneficial as a reference for future testing. In such cases the test direct voltage shall not exceed the original factory test rms alternating voltages.

Maximum Allowable Vibration Amplitude

RPM @

60 Hz

Velocity in/s peak

Velocity mm/s

RPM @

50 Hz

Velocity in/s peak

Velocity mm/s

3600 0.15 3.8 3000 0.15 3.8 1800 0.15 3.8 1500 0.15 3.8 1200 0.15 3.8 1000 0.13 3.3

900 0.12 3.0 750 0.10 2.5 720 0.09 2.3 600 0.08 2.0 600 0.08 2.0 500 0.07 1.7

Derived from NEMA publication MG 1–1998, Section 7.8.1, Table 7–1. Table is unfiltered vibration limits for resiliently mounted machines. For machines with rigid mounting multiply the limiting values by 0.8.

TABLE 100.11

— RESERVED —

TABLE 100.12.1

Bolt-Torque Values for Electrical Connections

US Standard Fasteners a Heat-Treated Steel – Cadmium or Zinc Plated b

Grade SAE 1&2 SAE 5 SAE 7 SAE 8

Head Marking

Minimum Tensile (Strength) (lbf/in2)

64K

105K

133K

150K

Bolt Diameter (Inches)

Torque (Pound-Feet)

1/4 4 6 8 8 5/16 7 11 15 18 3/8 12 20 27 30 7/16 19 32 44 48 1/2 30 48 68 74 9/16 42 70 96 105 5/8 59 96 135 145 3/4 96 160 225 235 7/8 150 240 350 380

1.0 225 370 530 570

a. Consult manufacturer for equipment supplied with metric fasteners.

b. Table is based on national coarse thread pitch.

TABLE 100.12.2

Silicon Bronze Fasteners b c

Torque (Pound-Feet)

Bolt Diameter (Inches) Nonlubricated Lubricated

5/16 15 10 3/8 20 15 1/2 40 25 5/8 55 40 3/4 70 60

a. Consult manufacturer for equipment supplied with metric fasteners.

b. Table is based on national coarse thread pitch.

c. This table is based on bronze alloy bolts having a minimum tensile strength of 70,000 pounds per square inch.

TABLE 100.12.3

Aluminum Alloy Fasteners b c

Bolt Diameter (Inches) Lubricated

5/16 10

3/8 14

1/2 25

5/8 40

3/4 60

a. Consult manufacturer for equipment supplied with metric fasteners.

b. Table is based on national coarse thread pitch.

c. This table is based on aluminum alloy bolts having a minimum tensile strength of 55,000 pounds per square inch.

TABLE 100.12.4

Stainless Steel Fasteners b c

Bolt Diameter (Inches) Uncoated

5/16 15

3/8 20

1/2 40

5/8 55

3/4 70

a. Consult manufacturer for equipment supplied with metric fasteners.

b. Table is based on national coarse thread pitch.

c. This table is to be used for the following hardware types:

Bolts, cap screws, nuts, flat washers, locknuts (18-8 alloy) Belleville washers (302 alloy).

Tables in 100.12 are derived from Square D Company, Anderson Products Division, General Catalog: Class 3910 Distribution Technical Data, Class 3930 Reference Data Substation Connector Products and Penn-Union Catalogue data.

TABLE 100.13

SF6 Gas Tests

Test Method Serviceability Limits a Moisture Hygrometer Per manufacturer or ≥ 200 ppmb SF6 decomposition byproducts ASTM D 2685 ≥ 500 ppm Air ASTM D 2685 ≥ 5000 ppmc Dielectric breakdown hemispherical contacts 0.10 inch gap at atmospheric pressure 11.5 - 13.5 kVd

a. In the absence of consensus standards dealing with SF6 circuit breaker gas tests, the NETA Standards Review Council suggests the above representative values.

b. According to some manufacturers.

c. Dominelli, N. and Wylie, L., Analysis of SF6 Gas as a Diagnostic Technique for GIS, Electric Power Research

Institute, Substation Equipment Diagnostics Conference IV, February 1996.

d. Per Even, F.E., and Mani, G. Sulfur Fluorides, Kirk, Othmer Encyclopedia of Chemical Technology, 4th ed., 11,428, 1994.

Reference: IEC 61634 High-Voltage Switchgear and Controlgear - Use and Handling of Sulfur Hexafluoride (SF6) in High-Voltage Switchgear and Controlgear.

TABLE 100.14

Insulation Resistance Conversion Factors (20° C)

Table 100.14.1 Test Temperatures to 20° C

Temperature Multiplier

° C ° F Apparatus Containing Immersed Oil Insulation

Apparatus Containing Solid Insulation

-10 14 0.125 0.25 -5 23 0.180 0.32 0 32 0.25 0.40 5 41 0.36 0.50

10 50 0.50 0.63 15 59 0.75 0.81 20 68 1.00 1.00 25 77 1.40 1.25 30 86 1.98 1.58 35 95 2.80 2.00 40 104 3.95 2.50 45 113 5.60 3.15 50 122 7.85 3.98 55 131 11.20 5.00 60 140 15.85 6.30 65 149 22.40 7.90 70 158 31.75 10.00 75 167 44.70 12.60 80 176 63.50 15.80 85 185 89.789 20.00 90 194 127.00 25.20 95 203 180.00 31.60

100 212 254.00 40.00 105 221 359.15 50.40 110 230 509.00 63.20

Derived from Stitch in Time…The Complete Guide to Electrical Insulation Testing, Megger.

Formula:

Rc = Ra x K Where: Rc is resistance corrected to 20° C

Ra is measured resistance at test temperature

K is applicable multiplier

Example: Resistance test on oil-immersion insulation at 104° Ra = 2 megohms @ 104° F K = 3.95 Rc = Ra x K Rc = 2.0 x 3.95 Rc = 7.90 megohms @ 20° C

TABLE 100.14 (continued)

Insulation Resistance Conversion Factors (40° C)

Table 100.14.2 Test Temperature to 40° C

Temperature Multiplier

° C

° F Apparatus Containing

Immersed Oil Insulation Apparatus Containing

Solid Insulation -10 14 0.03 0.10

-5 23 0.04 0.13 0 32 0.06 0.16 5 41 0.09 0.20

10 50 0.13 0.25 15 59 0.18 0.31 20 68 0.25 0.40 25 77 0.35 0.50 30 86 0.50 0.63 35 95 0.71 0.79 40 104 1.00 1.00 45 113 1.41 1.26 50 122 2.00 1.59 55 131 2.83 2.00 60 140 4.00 2.52 65 149 5.66 3.17 70 158 8.00 4.00 75 167 11.31 5.04 80 176 16.00 6.35 85 185 22.63 8.00 90 194 32.00 10.08 95 203 45.25 12.70

100 212 64.00 16.00 105 221 90.51 20.16 110 230 128.00 25.40

Derived from Megger’s Stitch in Time…The Complete Guide to Electrical Insulation Testing and ANSI/IEEE 43-2000, IEEE Recommended Practice for Testing Insulation Resistance of Rotating Machinery.

Notes: The insulation resistance coefficient is based on the halving of the insulation resistance to the change in temperature.

Apparatus Containing Immersed Oil Insulation Table uses 10° C change with temperature halving.

Apparatus Containing Solid Insulation Table uses 15° C change with temperature halving.

Formula:

Rc = Ra x K Where: Rc is resistance corrected to 40° C

Ra is measured resistance at test temperature K is applicable multiplier

Example: Resistance test on oil-immersion insulation at 68° F/20° C

Ra = 2 megohms @ 68° F/20° C K = 0.40 Rc = Ra x K Rc = 2.0 x 0.40 = 0.8 megohms @ 40° C

High-Potential Test Voltage Automatic Circuit Reclosers

Nominal Voltage Class, kV

Maximum Voltage, kV

Rated Impulse Withstand Voltage, kV

Maximum Field Test Voltage, kV, AC

14.4 15.0 95 35

14.4 15.5 110 50

24.9 27.0 150 60

34.5 38.0 150 70

46.0 48.3 250 105

69.0 72.5 350 160

Derived from ANSI/IEEE C37.61-1973(R1992), Standard Guide for the Application, Operation, and Maintenance of Automatic Circuit Reclosers and from C37.60-1981(R1992), Standard Requirements for Overhead, Pad-Mounted, Dry- Vault, and Submersible Automatic Circuit Reclosers and Fault Interrupters for AC Systems.

TABLE 100.219

High-Potential Test Voltage for Acceptance Testing of Line Sectionalizers

Nominal Voltage

Class kV

Maximum Voltage kV

Rated Impulse Withstand Voltage

Maximum Field Test

Voltage kV, AC

DC 15 Minute

Withstand (kV)

14.4 (1 ø) 15.0 95 35 53

14.4 (1 ø) 15.0 125 42 53

14.4 (3 ø) 15.5 110 50 53

24.9 (1 ø) 27.0 125 60 78

34.5 (3 ø) 38.0 150 70 103

Derived from ANSI/IEEE C37.63-1984(R1990) Table 2 (Standard Requirements for Overhead, Pad-Mounted, Dry- Vault, and Submersible Automatic Line Sectionalizers of ac Systems).

In the absence of consensus standards, the NETA Standards Review Council suggests the above representative values.

NOTE: Values of ac voltage given are dry test one minute factory test values.

TABLE 100.17

Dielectric Withstand Test Voltages

Metal-Enclosed Bus

Type of Bus

Rated kV

Maximum Test Voltage, kV

AC DC

24.5 37.0 52.0 Isolated Phase for Generator Leads 29.5 45.0 --

34.5 60.0 --

Isolated Phase for Other than Generator Leads

15.5 25.8 38.0

37.0 45.0 60.0

52.0

0.635 1.6 2.3

4.76 14.2 20.0

Nonsegregated Phase 15.0 27.0 37.0

25.8 45.0 63.0

38.0 60.0 --

15.5 37.0 52.0

Segregated Phase 25.8 45.0 63.0

38.0 60.0 --

0.3 1.6 2.3

0.8 2.7 3.9

DC Bus Duct 1.2 3.4 4.8

1.6 4.0 5.7

3.2 6.6 9.3

Derived from ANSI/IEEE C37.23-1987, Tables 3A, 3B, 3C, 3D and paragraph 6.4.2. The table includes a 0.75 multiplier with fractions rounded down.

NOTE:

The presence of the column headed “DC” does not imply any requirement for a dc withstand test on ac equipment. This column is given as a reference only for those using dc tests and represents values believed to be appropriate and approximately equivalent to the corresponding power frequency withstand test values specified for each class of bus.

Direct current withstand tests are recommended for flexible bus to avoid the loss of insulation life that may result from the dielectric heating that occurs with rated frequency withstand testing.

Because of the variable voltage distribution encountered when making dc withstand tests and variances in leakage currents associated with various insulation systems, the manufacturer should be consulted for recommendations before applying dc withstand tests to this equipment.

TABLE 100.18

Thermographic Survey Suggested Actions Based on Temperature Rise

Temperature difference (⊗T) based on comparisons between similar components under similar loading.

Temperature difference (⊗T) based upon comparisons between component and ambient air temperatures.

Recommended Action

1ºC - 3ºC 1ºC - 10ºC Possible deficiency; warrants investigation

4ºC - 15ºC 11ºC - 20ºC Indicates probable deficiency; repair as time permits

- - - - - - 21ºC - 40ºC Monitor until corrective measures can be accomplished

>15ºC >40ºC Major discrepancy; repair immediately

Temperature specifications vary depending on the exact type of equipment. Even in the same class of equipment (i.e., cables) there are various temperature ratings. Heating is generally related to the square of the current; therefore, the load current will have a major impact on ⊗T. In the absence of consensus standards for ⊗T, the values in this table will provide reasonable guidelines.

An alternative method of evaluation is the standards-based temperature rating system as discussed in Chapter 8.9.2, Conducting an IR Thermographic Inspection, Electrical Power Systems Maintenance and Testing, by Paul Gill, PE, 1998.

It is a necessary and valid requirement that the person performing the electrical inspection be thoroughly trained and experienced concerning the apparatus and systems being evaluated as well as knowledgeable of thermographic methodology.

TABLE 100.19

Dielectric Withstand Test Voltages

Electrical Apparatus Other than Inductive Equipment

Nominal System (Line) Voltagea (kV)

Class

AC Factory

Test (kV)

Maximum Field Applied AC Test (kV)

Maximum Field Applied DC Test (kV)

1.2 1.2 10 6.0 8.5

2.4 2.5 15 9.0 12.7

4.8 5.0 19 11.4 16.1

8.3 8.7 26 15.6 22.1

14.4 15.0 34 20.4 28.8

18.0 18.0 40 24.0 33.9

25.0 25.0 50 30.0 42.4

34.5 35.0 70 42.0 59.4

46.0 46.0 95 57.0 80.6

69.0 69.0 140 84.0 118.8

In the absence of consensus standards, the NETA Standards Review Council suggests the above representative values.

a. Intermediate voltage ratings are placed in the next higher insulation class.

TABLE 100.20

Rated Control Voltages and their Ranges for Circuit Breakers Operating mechanisms are designed for rated control voltages listed with operational capability throughout the indicated voltage ranges to accommodate variations in source regulation, coupled with low charge levels, as well as high charge levels maintained with floating charges. The maximum voltage is measured at the point of user connection to the circuit breaker [see notes (12) and (13)] with no operating current flowing, and the minimum voltage is measured with maximum operating current flowing.

100.20.1

(11) Rated Control

Voltage

Direct Current Voltage Ranges (1)(2)(3)(5)

Volts, dc (8)(9)

Opening Functions All Types

Rated Control Voltage

(60 Hz)

Alternating Current Voltage Ranges (1)(2)(3)(4)(8)

Closing, Tripping, and Auxiliary Functions

Closing and Auxiliary Functions

Indoor Circuit

Breakers

Outdoor Circuit

Breakers

Single Phase

Single Phase 24 (6) 48 (6)

--- 38–

100–140 200–280

36–56

90–140 180–280

14–28 28–56

70–140 140–280

104–127 (7) 208–254 (7)

Polyphase Polyphase 208Y/120

180Y/104–220Y/127

208–254

Derived from Table 8, ANSI C37.06-2000, AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis

— Preferred Ratings and Related Required Capabilities.

Notes:

(1) Electrically operated motors, contactors, solenoids, valves, and the like, need not carry a nameplate voltage rating that corresponds to the control voltage rating shown in the table as long as these components perform the intended duty cycle (usually intermittent) in the voltage range specified.

(2) Relays, motors, or other auxiliary equipment that function as a part of the control for a device shall be subject to the voltage limits imposed by this standard, whether mounted at the device or at a remote location.

(3) Circuit breaker devices, in some applications, may be exposed to control voltages exceeding those specified here due to abnormal conditions such as abrupt changes in line loading. Such applications require specific study, and the manufacturer should be consulted. Also, application of switchgear devices containing solid-state control, exposed continuously to control voltages approaching the upper limits of ranges specified herein, require specific attention and the manufacturer should be consulted before application is made.

(4) Includes supply for pump or compressor motors. Note that rated voltages for motors and their operating ranges are covered by ANSI/NEMA MG-1-1978.

(5) It is recommended that the coils of closing, auxiliary, and tripping devices that are connected continually to one dc potential should be connected to the negative control bus so as to minimize electrolytic deterioration.

(6) 24-volt or 48-volt tripping, closing, and auxiliary functions are recommended only when the device is located near the battery or where special effort is made to ensure the adequacy of conductors between battery and control terminals.

24-volt closing is not recommended.

(7) Includes heater circuits

TABLE 100.20 (continued)

(8) Voltage ranges apply to all closing and auxiliary devices when cold. Breakers utilizing standard auxiliary relays for control functions may not comply at lower extremes of voltage ranges when relay coils are hot, as after repeated or continuous operation.

(9) Direct current control voltage sources, such as those derived from rectified alternating current, may contain sufficient inherent ripple to modify the operation of control devices to the extent that they may not function over the entire specified voltage ranges

(10) This table also applies for circuit breakers in gas insulated substation installations.

(11) In cases where other operational ratings are a function of the specific control voltage applied, tests in C37.09 may refer to the “Rated Control Voltage.” In these cases, tests shall be performed at the levels in this column.

(12) For an outdoor circuit breaker, the point of user connection to the circuit breaker is the secondary terminal block point at which the wires from the circuit breaker operating mechanism components are connected to the user’s control circuit wiring.

(13) For an indoor circuit breaker, the point of user connection to the circuit breaker is either the secondary disconnecting contact (where the control power is connected from the stationary housing to the removable circuit breaker) or the terminal block point in the housing nearest to the secondary disconnecting contact.

100.20.2

Solenoid-Operated Devices

Closing Voltage Ranges for Power Supply

125 dc 250 dc 230 ac

90 - 115 or 105 - 130 180 - 230 or 210 - 260 190 - 230 or 210 - 260

Some solenoid operating mechanisms are not capable of satisfactory performance over the range of voltage specified in the standard; moreover, two ranges of voltage may be required for such mechanisms to achieve an acceptable standard of performance.

The preferred method of obtaining the double range of closing voltage is by use of tapped coils. Otherwise it will be necessary to designate one of the two closing voltage ranges listed above as representing the condition existing at the device location due to battery or lead voltage drop or control power transformer regulation. Also, caution should be exercised to ensure that the maximum voltage of the range used is not exceeded.

TABLE 100.21

Accuracy of IEC Class TP Current Transformers Error Limit

Class

At Rated Current At Accuracy Limit Condition

Ratio Error (%) Phase Displacement Minimum

Peak Instantaneous Error

TPX ± 0.5 ± 30 10

TPY ± 1.0 ± 60 10

TPZ ± 1.0 180 ± 18 10 (see note)

NOTE – Alternating current component error.

There are four different TP classifications to meet different functional requirements as follows:

1. Class TPS low leakage flux design ct.

2. Class TPX closed core ct for specified transient duty cycle.

3. Class TPY gapped (low remanance) ct for specified transient duty cycle

4. Class TPZ linear ct (no remanence).

The error limit for TPS ct in terms of turn ratio error is ± .25% and the excitation voltage under limiting conditions should not be less than the specified value; furthermore, this value is such that an increase of 10% in magnitude does not result in an increase in the corresponding peak instantaneous exciting current exceeding 100%. In other words, the ct should not be in saturated state at the specified maximum operating voltage.

The accuracy limit conditions are specified on the rating plate. The required rating plate information is shown in the table below. (The obvious information such as rated primary and secondary currents are not shown).

CT Class TPS TPX TPY TPZ

Symmetrical short-circuit current factor x x x x Rated resistive burden (Rb) x x x x Secondary winding resistance (at .. o C) x x x x Rated Transient dimensioning factor - x x x Steady-state error limit factor x - - - Excitation limiting secondary voltage x - - - Accuracy limiting secondary exciting current x - - - Factor of construction* - x x x Rated secondary loop time constant - - x - Specified primary time constant (Tp) - x x x Duty cycle - x x -x = applicable, – = not applicable *The factor construction is determined from the following ratio:

Equivalent secondary accuracy limiting voltage (Valc) Equivalent secondary accuracy limiting e.m.f (Ealc) where Valc is the mts value of sinusoidal voltage of rated frequency, with, if applied to the secondary winding of a ct, would result in an exciting current corresponding to the maximum permissible error current appropriate to ct class Ealc is the equivalent rms emf of rated frequency determined during test observed error current corresponds to the appropriate limit for the class Derived from C37.110

TABLE 100.22

Minimum Radii for Power Cable Single & Multiple Conductor Cables with Interlocked Armor, Smooth or

Corrugated Aluminum Sheath or Lead Sheath

Cable Type

Overall Diameter of Cable inches mm

0.75 190

& less & less inches mm

0.76 to 191 to

1.50 381 inches mm

1.51 & 382 & larger larger

Minimum Bending Radius as a Multiple of Cable Diameter Smooth Aluminum Sheath Single Conductor Nonshielded, Multiple Conductor or Multiplexed, with Individually Shielded Conductors

Single Conductor Shielded 12 12 15 Multiple Conductor or Multiplexed, with Overall Shield 12 12 15

Interlocked Armor or Corrugated Aluminum Sheath Nonshielded 7 7 7

Multiple Conductor with Individually Shielded Conductor 12/7 a 12/7 a 12/7 a

Multiple Conductor with Overall Shield 12 12 12

Lead Sheath 12 12 12

ANSI/ICEA S-93-639/NEMA WC 74-2000, 5-46 kV Shielded Power Cable for Use in the Transmission and Distribution of Electric Energy, Appendix I – Recommended Bending Radii for Cables and Table I1 – Minimum Radii for Power Cable.

a. 12 x individual shielded conductor diameter, or 7 x overall cable diameter, whichever is greater.

TABLE 100.22

Minimum Radii for Power Cable

Single & Multiple Conductor Cables with Interlocked Armor, Smooth or Corrugated Aluminum Sheath or Lead Sheath

Notes

Specific references from Appendix I:

1. Interlocked-Armor and Metallic-Sheathed Cables

1.1 The minimum bending radius for interlocked-armored cables, smooth or corrugated aluminum sheath or lead sheath shall be in accordance with Table 100.22.

2. Flat-Tape Armored or Wire-Armored Cables

2.1 The minimum bending radius for all flat-tape armored and all wire-armored cables is twelve times the overall diameter of cable.

3. Tape-Shielded Cables

3.1 The minimum bending radius for tape-shielded cables given above applies to helically applied flat or corrugated tape or longitudinally applied corrugated tape-shielded cables.

3.2 The minimum bending radius for a single-conductor cable is twelve times the overall diameter.

3.3 For multiple-conductor or multiplexed single-conductor cables having individually taped shielded conductors, the minimum bending radius is twelve times the diameter of the individual conductors or seven times the overall diameter, whichever is greater.

3.4 For multiple-conductor cables having an overall tape shield over the assembly, the minimum bending radius is twelve times the overall diameter of the cable.

4. Wire-Shielded Cables

4.1 The minimum bending radius for a single-conductor cable is eight times the overall diameter.

4.2 For multiple-conductor or multiplexed single-conductor cables having wire-shielded individual conductors, the minimum bending radius is eight times the diameter of the individual conductors or five times the overall diameter, whichever is greater.

4.3 For multiple-conductor cables having a wire shield over the assembly, the minimum bending radius is eight times the overall diameter of the cable.

APPENDIX A

Definitions

NETA recognizes the IEEE 100, The Authoritative Dictionary of IEEE Standards Terms, as its official source for electrical definitions. The definitions in the list provided by NETA are either not included in the IEEE reference or are more specific to electrical testing and to this document.

NETA defines equipment voltage ratings in accordance with ANSI/NEMA C37.84.1 American National Standard for Electrical Power Systems and Equipment – Voltage Ratings (60 Hertz).

As-found Condition of the equipment when taken out of service, prior to testing.

As-left Condition of equipment at the completion of inspection and testing. As-left values refer to test values obtained after any corrective action or design change has been performed on the device under test.

Comment Suggested revision, addition, or deletion in an existing section of the NETA specifications.

Electrical tests Electrical tests involve application of electrical signals and observation of the response. It may be, for example, applying a potential across an insulation system and measuring the resultant leakage current magnitude or power factor or dissipation factor. It may also involve application of voltage and/or current to metering and relaying equipment to check for correct response.

Equipment condition Suitability of the equipment for continued operation in the intended environment as determined by evaluation of the results of inspections and tests.

Exercise To operate equipment in such a manner that it performs all its intended functions to allow observation, testing, measurement, and diagnosis of its operational condition.

Extra-high voltage A class of nominal system voltages greater than 230,000 volts.

High voltage A class of nominal system voltages equal to or greater than 100,000 volts and equal to or less than 230,000 volts.

Inspection Examination or measurement to verify whether an item or activity conforms to specified requirements.

Interim amendment A interim amendment is made by NETA’s Standards Review Council when there is a potential hazard prior to review by the Section Panel or the public.

APPENDIX A

Definitions (continued) Low voltage A class of nominal system voltages 1000 volts or less.

Manufacturer’s published data Data provided by the manufacturer concerning a specific piece of equipment.

Mechanical inspection Observation of the mechanical operation of equipment not requiring electrical stimulation, such as manual operation of circuit breaker trip and close functions. It may also include tightening of hardware, cleaning, and lubricating.

Medium voltage A class of nominal system voltages greater than 1000 volts and less than 100,000 volts.

Proposal Draft of a section that is currently “reserved” in one of the NETA specifications.

Ready-to-test condition Having the equipment which is to be tested isolated, source and load disconnected, the equipment grounded, and control and operating sources identified.

Shall Indicates a mandatory requirement and is used when the testing firm has control over the result.

Should Indicates that a provision is not mandatory but is recommended as good practice.

System voltage The root-mean-square (rms) phase-to-phase voltage of a portion of an alternating-current electric system.

Each system voltage pertains to a portion of the system that is bounded by transformers or utilization equipment.

Verify To investigate by observation or by test to determine that a particular condition exists.

Visual inspection Qualitative observation of physical characteristics, including cleanliness, physical integrity, evidence of overheating, lubrication, etc.