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Power Quality Research Lab., I-7, Wyb. Wyspiaoskiego 27, 50-370 Wrcaw, Plandphone +48713202626, fax +48713202006, email:[email protected]

POWER QUALITY REPORT

Facility: XXX

Start Monitoring: XX Stop Monitoring: XX

Received Data: XX Report Generated: XX

Survey Type: Equipment Installed and Operating

Project Manager: Zbigniew Leonowicz, PhD Eng.

Collaborators: XXX

SUMMARY OF REPORT:

Power quality assessment showed no significant issues. Voltages over upper limit

were detected mainly in L2 of the 110 kV distribution network.
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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Power Quality Report 2010-12-27

Page 2

Category Summary AnalysisAcceptable

Need

sFollow-Up

Problem

NotA

pplicable

GENERATOR (10,5 kV)

Harmonic current factor Values within the limits

Symmetrical

components of currents

Values within the limits

Ratio of the negative-

sequence component of

current to the ratedcurrent


Voltage and frequency

limits during operation


Voltage dependence of

the generator frequency


Events No events recorded

DISTRIBUTION NETWORK (110 kV)

Power frequencyassessment


Long-term flicker

severity


Unbalance Values within the limits

Harmonics Values within the limits

THD Values within the limits

Voltage Values within the limits

Events Overvoltages, Voltage over RMS

upper limit mainly in L2, see page

25.


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CONTENT

1. MEASUREMENTS RELATED TO AC GENERATOR ....................................................................................... 4

1.1. MEASURING EQUIPMENT ...................................................................................................................... 4

1.2. ACGENERATOR PARAMETERS ................................................................................................................ 4

1.3. HARMONIC CURRENT FACTOR (HCF) ........................................................................................................ 8

1.4. SYMMETRICAL COMPONENTS OF CURRENTS ............................................................................................... 9

1.5. RATIO OF THE NEGATIVE-SEQUENCE COMPONENT OF CURRENT TO THE RATED CURRENT (I2/IN) ............................. 11

1.6. VOLTAGE AND FREQUENCY VARIATIONS DURING OPERATION......................................................................... 12

1.7. VOLTAGE DEPENDENCE OF THE GENERATOR FREQUENCY .............................................................................. 15

1.8. SUMMARY OF THE REPORT

................................................................................................................... 15

2. MEASUREMENTS RELATED TO 110 KV DISTRIBUTION NETWORK .......................................................... 17

2.1. MEASURING EQUIPMENT .................................................................................................................... 17

2.2. POWER FREQUENCY ASSESSMENT .......................................................................................................... 17

2.3. LONG TERM FLICKER SEVERITY............................................................................................................... 19

2.4. VOLTAGE UNBALANCE ASSESSMENT ....................................................................................................... 20

2.5. HARMONICS ASSESSMENT ................................................................................................................... 21

2.6. SUPPLY VOLTAGE VARIATION ................................................................................................................ 24

2.7. EVENTS........................................................................................................................................... 25

2.8. SUMMARY OF THE REPORT ................................................................................................................... 26

3. LITERATURE........................................................................................................................................... 26


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1. Measurements related to AC generator

In this chapter, the power quality (PQ) report contains assessment of set of PQ parameters

recorded indirectly at the AC generator (10,5 kV). Recorded values were compared with

recommended values. Power quality report includes assessment of :

harmonic current factor (HCF) [4]

system of currents symmetrical components [4]

ratio of the negative-sequence component of current to the rated current [4]

voltage and frequency variations during operation [4]

voltage dependence of the generator frequency [5]

recorded power quality events and transients

Measurements were done on the voltage and current transformers terminals in the XXX

Localization of the power quality recorder in the generator circuitry presents XX

1.1.Measuring equipmentFluke 1760, Three-Phase Power Quality Recorder Topas, Serial No. Y760588, GPS time

synchronization, Class-A compliance.

1.2.AC Generator Parameters

Manufacturer: XXX Type: XXX

Air cooled turbo generator, apparent power 76 MVA, rated voltage 10,5 kV, current 4205 A,

power factor 0,85, speed 3000 rpm.

The generator parameters during 1 week assessment time are shown in Table 1-1:


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Table 1-1. Generator parameters during the assessment period

Parameter

Values

minPercen-

tile 95% max

Active power P [MW] 24,515 62,975 64,291

Reactive power Q[MVAr] 2,604 18,361 22,961

Apparent Power S [MVA] 24,752 64,802 66,782

cos 0,934 0,994 0,999

tan 0,045 0,110 0,382

Power factor PF 0,964 0,993 0,998

PF is defined as: PF=(P/|S|)(Qh/|Qh|)

Fig. 1.1. Visualization of the generatrs active pwer in 1 week. (yellow line sum of three phase quantities)


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Fig. 1.2. Visualization of the generatrs reactive pwer in 1 week.

Fig. 1.3. Visualization of the generatrs apparent pwer in 1 week.


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Fig. 1.4. Visualization of the generatrs pwer factr (cs) in 1 week.

Fig. 1.5. Visualization of the generatrs pwer factr (PF=(P/|S|)*(Qh/|Qh|)) in 1 week.


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Fig. 1.6. Localization of the power quality measurements in the generator circuitry.

1.3.Harmonic current factor (HCF)

Three-phase a.c. generators shall be suitable for supplying circuits which, when supplied by a

system of balanced and sinusoidal voltages result in currents not exceeding a harmonic

current factor (HCF) of 5% [4].

The HCF shall be computed by using the following formula:

where in is the ratio of the harmonic current In to the rated current IN; n is the order of

harmonic; k= 13. Harmonic components are shown in Fig. 1.7.

Table 1-2. Assessment of the HCF

HCF assessmentHCF

[%]

min 1,01

Percentile 95% 1,69

max 1,83

During 100% of the assessment period the maximum HCF values are within the range of

1,01% 1,83%, all below the limit of 5%.


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Fig. 1.7. Visualizatin f the currents harmnics averaged over 1 week. (in all figures the plots of L1 are blue,

L2-red, L3-green)

1.4.Symmetrical components of currentsThree-phase a.c. generators shall be suitable for supplying circuits which, when supplied by a

system of balanced and sinusoidal voltages result in a system of currents where neither the

negative-sequence component nor the zero-sequence component exceed 5% of the

positive-sequence component [4]. Currents symmetrical components are shown in Fig. 1.8

and 1.9.


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Fig. 1.8. Visualization of currents Zero to Positive sequence ratio.

Fig. 1.9. Visualization of currents Negative to Positive sequence ratio.


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Table 1-3. Assessment of the negative and zero-sequence components

Components ratio

assessment

Components ratio

[%]

min

Percen-

tile 95% max

Zero/Pos 0,43 0,50 0,50

Neg/Pos 0,55 1,11 2,35

During 100% of the assessment period measured values hold in range from 0,43% to 0,50%

for zero sequence component and from 0,55% to 2,35% for negative sequence component,

all below the limit of 5%.

1.5.Ratio of the negative-sequence component of current to the rated

current (I2/IN)

Three-phase synchronous machines shall be capable of operating continuously on an

unbalanced system in such a way that, with none of the phase currents exceeding the rated

current, the ratio of the negative-sequence component of maximum current for continuous

operation (I2) to the rated current (IN) does not exceed the value of 8% for a.c. generators

with direct cooled (inner cooled) rotor windings [4].

Table 1-4. Assessment of the I2/IN

I2/IN assessmentI2/IN

[%]

I2/IN min 0,008

I2/IN Percentile 95% 0,152

I2/IN max 0,356


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Fig. 1.10. Visualization of currents I2/IN ratio.

Figure 1.10 and Table 1-4 contains statistical parameters which confirmed that in the

investigated case requirements for I2/I

Nare fulfilled. The recorded r.m.s. values hold in range

from 0,008% to 0,356%.

1.6.Voltage and frequency variations during operation

For a.c. machines rated for use on a power supply of fixed frequency supplied from an a.c.

generator (whether local or via a supply network), combinations of voltage variation and

frequency variation are classified as being either zone A or zone B, in accordance with Figure

1.11 for generators and synchronous condensers. A machine shall be capable of performing

its primary function, continuously within zone A, but need not comply fully with its

performance at rated voltage and frequency [4].


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Fig. 1.11. Voltage and frequency limits for generators with plotted limit range of recorded values (red

rectangle).

Table 1-5. Assessment of voltage and frequency limits

Voltage and frequency limitsU f

[p.u.] [p.u.]

U,

f

min 0,9997 0,9981

Percentile 95% 1,0255 1,0010

max 1,0257 1,0016


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Fig. 1.12. Visualization of voltage variation in 1 week.

Fig. 1.13. Visualization of frequency variation in 1 week.


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Visualization of the recorded data in Figures 1.12 and 1.1.3 and Table 1-5 contain statistical

parameters which confirmed that in the investigated case requirements for voltage and

frequency limits are fulfilled.

1.7.Voltage dependence of the generator frequency

The generating unit should maintain the following relationship between the frequency of the

generator and voltage [5]

where f is the change of frequency in p.u. and Ug is the change of generator voltage

corresponding to the change of frequency, in p.u.

Table 1-6. Assessment of voltage dependence on generator frequency

Ug/f

[p.u.]

Ug/f10min

Ug 1,64910-5

f 8,39910-4

max 0,0196

For measured data, the maximum of numerical approximate gradient showed the point

where the change of frequency was the highest (22.11.2010 06:00:00), see Table 1-6.

Corresponding change of voltage was determined and the ratio Ug/f computed at this

time point [2]. The requirements are fulfilled.

1.8.Summary of the report

Presented in previous section assessment of crucial power quality parameters indicates that:

in case of harmonic current factor (HCF), requirements are fulfilled

in case of system of currents symmetrical components, requirements are fulfilled

in case of the ratio of the negative-sequence component of current to the rated current ,

requirements are fulfilled

in case of voltage and frequency variations during operation , requirements are fulfilled

in case of voltage dependence of the generator frequency, requirements are fulfilled

for


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During the assessment period no events were detected (with exception to one generator

disconnection from the grid due to causes not relevant to power quality assessment).


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2. Measurements related to 110 kV distribution network

In this chapter, the power quality (PQ) report contains assessment of set of PQ parameters

recorded indirectly at power line of the distribution network (110 kV). Recorded values were

compared with recommended values. Power quality report includes assessment of :

power frequency

long term flicker severity

voltage unbalance

harmonics

recorded power quality events and transients

2.1.Measuring equipment

Fluke 1760, Three-Phase Power Quality Recorder Topas, Serial No. UO13379, GPS time

synchronization, Class-A compliance. Measurements were done on the voltage and current

transformers terminals of transmission line 1 in XXX.

Localization of the power quality recorder in the distribution network of the 110 kV line

No. 1 presents XX

Fig. 2.1. Localization of the power quality measurements in 110 kV distribution network.

2.2.Power frequency assessment

The standards [3] and [4] indicate that the nominal frequency of the supply voltage shall be

50 Hz. Under normal operating conditions the mean value of the fundamental frequency

measured over 10 s shall be within a range of:

for systems with synchronous connection to an interconnected system with the voltage

below 220 kV:


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50 Hz 1 % (i.e. 49,5 Hz... 50,5 Hz) during 99,5 % of a week;

50 Hz + 4 % / - 6 % (i.e. 47 Hz... 52 Hz) during 100 % of the week;

Fig. 2.2. Visualization of power frequency variation.

Table 2-1. Assessment of power frequency variation

Frequency assessmentf

[Hz]

f10s min 49,905

f10s Percentile 99,5% 50,009

f10s max 50,109

Visualization of the recorded set of frequency values is shown in Fig. 2.2.

Figure 2.2 and Table 1-2 contains the statistical parameters which confirmed that in the

investigated case requirements for frequency standards are fulfilled. During 100% of the

assessment period frequency values hold in range from 49,905 to 50,109 Hz.


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2.3.Long term flicker severity

Fig. 2.3. Visualization of long-term flicker severity

Table 2-2. Assessment of long-term flicker severity

Flicker assessmentL1 L2 L3

[-] [-] [-]

Plt2h

min 0,15 0,16 0,15

Percentile 95% 0,73 0,65 0,63

max 0,75 0,66 0,64

Visualization of the recorded set of long-term flicker coefficient values is shown in Fig 2.3.

The standards indicate that under normal operating conditions, in any period of one week

the long term flicker severity caused by voltage fluctuation shuld be Plt 0,8 fr 95 % f the

time [5].

Table 2-2 contains the statistical parameters which confirmed that in the investigated case

requirements for flicker severity are fulfilled. 95% of the recorded long-term flicker values

hold in range from 0,15 to 0,75. Moreover 100% of the recorded values follows by the

standard expectation.


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2.4.Voltage unbalance assessment

Fig. 2.4. Visualization of the voltage unbalance variation

Table 2-3. Assessment of unbalance variation

Unbalance assessmentNeg/Ps

[%]

Neg/Pos10min

min 0,15

Percentile 95% 0,26

max 0,29

Visualization of the recorded set of unbalance values is shown in Fig. 2.4. The standard [4]

indicates that under normal operating conditions, during each period of one week, 95 % of

the 10 min mean r.m.s. values of the negative phase sequence component (fundamental) of

the supply voltage shall be within the range 0 % to 1 % of the positive phase sequence

component (fundamental).

Table 2-3 contains statistical parameters which confirm that in the investigated case

requirements for unbalance standards are fulfilled. The recorded unbalance coefficient hold

in range from 0,15% to 0,29%.(with 95% values not greater than 0,26%).


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2.5.Harmonics assessment

Table 2-4. Assessment of harmonic variations

Harmonic assessment

Percentile95% MaxOrder Limits L1 L2 L3 L1 L2 L3

Nr. [ % ] [ % ] [ % ] [ % ] [ % ] [ % ] [ % ]

2 1,50 0,06 0,06 0,06 0,09 0,09 0,08

3 2,00 0,26 0,30 0,15 0,28 0,33 0,19

4 1,00 0,03 0,02 0,02 0,04 0,03 0,04

5 2,00 0,74 0,66 0,71 0,90 0,89 0,95

6 0,50 0,02 0,02 0,02 0,04 0,03 0,03

7 2,00 0,41 0,39 0,39 0,53 0,48 0,50

8 0,50 0,03 0,02 0,03 0,05 0,05 0,05

9 1,00 0,04 0,04 0,04 0,07 0,07 0,07

10 0,50 0,03 0,03 0,03 0,07 0,06 0,07

11 1,50 0,14 0,16 0,15 0,18 0,19 0,19

12 0,50 0,02 0,02 0,02 0,02 0,02 0,02

13 1,50 0,19 0,19 0,19 0,27 0,28 0,28

14 0,50 0,02 0,02 0,02 0,03 0,03 0,03

15 0,50 0,02 0,02 0,02 0,03 0,03 0,03

16 0,50 0,01 0,01 0,01 0,02 0,02 0,02

17 0,00 0,10 0,10 0,12 0,13 0,12 0,15

18 0,50 0,01 0,01 0,02 0,02 0,03 0,03

19 1,00 0,07 0,06 0,06 0,09 0,10 0,08

20 0,50 0,01 0,01 0,01 0,02 0,03 0,03

21 0,50 0,01 0,01 0,01 0,03 0,03 0,03

22 0,50 0,01 0,01 0,01 0,02 0,02 0,02

23 0,70 0,07 0,08 0,08 0,11 0,14 0,11

24 0,50 0,01 0,01 0,01 0,02 0,03 0,02

25 0,70 0,07 0,06 0,07 0,13 0,11 0,13

26* 0,680,01 0,01 0,01 0,01 0,01 0,01

27* 0,660,01 0,01 0,01 0,01 0,01 0,01

28* 0,650,01 0,01 0,01 0,01 0,01 0,01

29* 0,630,02 0,02 0,02 0,02 0,02 0,02

30* 0,620,01 0,01 0,01 0,01 0,01 0,01

31* 0,60 0,02 0,02 0,02 0,02 0,02 0,02


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32* 0,590,01 0,01 0,01 0,01 0,01 0,01

33* 0,580,01 0,01 0,01 0,01 0,01 0,01

34* 0,570,01 0,01 0,01 0,01 0,01 0,01

35* 0,560,02 0,02 0,02 0,02 0,02 0,02

36* 0,550,01 0,01 0,01 0,01 0,01 0,01

37* 0,540,02 0,02 0,02 0,02 0,02 0,02

38* 0,530,01 0,01 0,01 0,01 0,01 0,01

39* 0,520,01 0,01 0,01 0,01 0,01 0,01

40* 0,510,01 0,01 0,01 0,01 0,01 0,01

41* 0,500,02 0,02 0,03 0,02 0,02 0,03

42* 0,500,01 0,01 0,01 0,01 0,01 0,01

43* 0,490,02 0,03 0,03 0,02 0,03 0,03

44* 0,480,01 0,01 0,01 0,01 0,01 0,01

45* 0,480,01 0,01 0,02 0,01 0,01 0,02

46* 0,470,01 0,01 0,01 0,01 0,01 0,01

47* 0,470,02 0,02 0,02 0,02 0,02 0,02

48* 0,460,01 0,01 0,01 0,01 0,01 0,01

49* 0,460,02 0,01 0,01 0,02 0,01 0,01

50* 0,450,01 0,01 0,01 0,01 0,01 0,01

*For harmonics higher than 25th

the formula for the harmonic limit is 0,2+0,5(25/h) [%] [5].

Fig, 2.5. Visualization ofthe vltages harmonic spectrum averaged in 1 week.


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Table 2-4 contains limits for particular harmonics defined in [5] and statistical parameters of

recorded data. Distribution of the harmonics is also visible in Fig, 2.5. Performed

measurements has detected no values over the limit.

Fig, 2.6. Visualization of THDV variation

Table 2-5. Assessment of THDV variation

THDV assessmentTHDVL1 THDVL2 THDVL3

[%] [%] [%]

THDV

10min

min 0,37 0,38 0,29

Percentile 95% 0,88 0,81 0,83

max 0,99 0,99 1,02

Visualization of the recorded set of total harmonics distortion in voltage is shown in Fig. 2-6,

[5] indicates THD of the supply voltage (including all harmonics up to the order 40) shall be

less than or equal to 3 %.

Table 2-5 contains the statistical parameters of THDV which confirmed that in the

investigated case requirements are fulfilled, 95% of the recorded THDV coefficient hold in


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range from 0,83% to 0,88%, Moreover 100% of the recorded values follow by the standard

expectation.

2.6.Supply voltage variation

Fig. 2.7. Visualization of supply voltage variation.

Table 2-6. Assessment of supply voltage variation

Voltage assesmentVL1 VL2 VL3

[V] [V] [V]

U10min

min67609,00 67837,00 67683,00

Percentile 95% 69407,25 69648,00 69441,50

max69677,00 69948,00 69698,00

Visualization of the recorded set of supply voltage values is shown in Fig, 2.7. The [5]

indicates that under normal operating conditions:

- during each period of one week 95 % of the 10 min mean r.m.s. values of the supply

voltage shall be within the range f Un 10 %, i.e. in the range 57157,68 69859,38 V.

Table 2-6 contains statistical parameters which confirmed that in the investigated case

requirements for r.m.s. supply voltage standards are fulfilled, 95% of the recorded r.m.s.,


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values hold in range from 69407,25 V to 69648,00 V Moreover 100% of the recorded values

follows by standard expectation, i.e. are within the range of 50806,82 V 76210,23 V.

2.7.Events

During the assessment period the following events were detected:

Overvoltages

Designation L1 L2 L3 L123-N

Number 1 4 1 4

Maximum value [V] 69879 70136 69900 70136

Maximum duration 4h 56m 26s 8h 51m 14s 6h 9m 33s 8h 51m 14s

Details of recorded events

Event Location DetectionDate &Time

Duration Value

Voltage Swells V L3 21.11.201000:45:43,71

6h 9m 33s 6,99e+04 [V]


4h 56m 26s 6,988e+04 [V]


8h 51m 14s 7,014e+04 [V]


5h 16m 0s 7,003e+04 [V]


4h 8m 3s 6,999e+04 [V]


4h 5m 8s 6,991e+04 [V]

Voltage Swells 3-ph V L123-N 22.11.201000:47:40,70

8h 51m 14s 7,014e+04 [V]


5h 16m 0s 7,003e+04 [V]


4h 8m 3s 6,999e+04 [V]


4h 5m 8s 6,991e+04 [V]

RMS Upper Limit V L3 22.11.201008:33:09,62

4h 44m 5s 6,987e+04 [V]


10h 19m 45s 7,012e+04 [V]


6h 11m 40s 7,001e+04 [V]


4h 33m 42s 6,996e+04 [V]


4h 23m 59s 6,989e+04 [V]

h06 Harmonics V L2 24.11.201009:15:00,91

200,06ms 0,5343 [%]

h06 Harmonics V L1 24.11.201014:27:37,11

200,05ms 0,5235 [%]

h06 Harmonics V L1 24.11.2010

15:38:24,90

199,88ms 0,501 [%]

h06 Harmonics V L1 25.11.201002:05:16,99

999,77ms 0,5519 [%]


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h06 Harmonics V L1 25.11.201002:05:16,99

199,99ms 0,5788 [%]

h06 Harmonics V L1 25.11.201002:05:19,01

1,0002s 0,5491 [%]

h06 Harmonics V L1 25.11.201005:29:01,27

200,05ms 0,5054 [%]

h06 Harmonics V L3 25.11.201007:55:14,98

200,11ms 0,5294 [%]

h12 Harmonics V L1 25.11.201012:44:23,45

199,96ms 0,7392 [%]

2.8.Summary of the report

Presented in previous section assessment of crucial power quality parameters indicates that:

in case of power frequency, requirements are fulfilled

in case of voltage supply, requirements are fulfilledin case of flicker severity, requirements are fulfilled

in case of voltage unbalance, requirements are fulfilled

in case of THD of the supply voltage, requirements are fulfilled

in case of harmonics, requirements are fulfilled

Multiple events were detected during the recording time. Closer follow-up require the

overvoltages.

3. Literature

[1] IEC 61000-4-30:2008, Electromagnetic compatibility (EMC): Testing and measurement

techniques -Power quality measurement method

[2]Bollen M,H,J, Irene Yu-Hua Gu, Signal Processing of Power Quality Disturbances, 2006

The Institute of Electronics and Electrical Engineers, Inc

[3]EN 50160: Voltage characteristics of electricity supplied by public distribution networks

[4] IEC 60034-1: Rotating electrical machines: 7 Electrical operating conditions

[5]Regulations of the operation and exploitation of the distribution network

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