Electricity Quality of Service and Supply Standards · 12.‘low voltage’ (LV) means a nominal phase-to-phase voltage not exceeding 400 Volts 13.‘medium voltage’ (MV) means

Lesotho Electricity Authority

Electricity Quality of Service and Supply Standards

First Edition: 2006

Table of Contents

0 Abbreviations ...................................................................................................................... 3 1 Definitions ........................................................................................................................ 3 2 Background and Scope ..................................................................................................... 4 3 Quality of Service Standards ............................................................................................ 5

3.1 Service Activities for the Processing of Requests for Supply ................................... 5 3.2 Service Activities for Credit Metering ...................................................................... 6

3.2.1 Information Availability ..................................................................................... 6 3.2.2 Payment Venues ................................................................................................. 8

3.3 Service Activities for Prepayment Metering ............................................................. 8 3.3.1 Information Availability ..................................................................................... 8

3.4 Network Faults ........................................................................................................ 11 3.5 Customer Complaints, Enquiries and Requests ....................................................... 13 3.6 Communication Services .......................................................................................... 14 3.7 Customer Education ................................................................................................. 14

4 Quality of Supply Standards .......................................................................................... 15 4.1 Frequency ................................................................................................................. 15 4.2 Voltage Regulation .................................................................................................. 16 4.3 Voltage Unbalance .................................................................................................. 17 4.4 Voltage Harmonics and Interharmonics* ................................................................ 18 4.5 Voltage Flicker* ...................................................................................................... 18 4.6 Inter-utility Interfaces .............................................................................................. 18

Annex A .............................................................................................................................. 20 Annex B .............................................................................................................................. 21

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0 Abbreviations AGC - Automatic Generation Control CPS - Control Performance Standard EHV - Extra High Voltage HV - High Voltage IEC - International Electrotechnical Commission LEA - Lesotho Electricity Authority LV - Low Voltage MV - Medium Voltage PCC - Point of Common Coupling SAPP- Southern African Power Pool UB - (Voltage) Unbalance

1 Definitions1. ‘Act’ means the Lesotho Electricity Authority Act No. 12 of 2002;2. ‘assessed level’ means the level of performance measured and statistically

processed according to given rules;3. ‘compatibility level’ (electromagnetic compatibility level) means the

specified disturbance level at which an acceptable, high probability of electromagnetic compatibility exists (IEC 161-03-10/A). It is the level used for coordinating the utility network performance levels and the sensitivity of customers and electrical equipment;

4. ‘customer’ means a person (including a legal entity) who either has entered or is to enter into an electricity supply agreement with a licensee, or legally consumes electricity (as an end consumer) supplied by that licensee;

5. ‘declared voltage’ means the voltage declared by the licensee at the point of supply;

6. ‘extra high voltage’ (EHV) means a nominal phase-to-phase voltage in excess of 132 kilo Volts;

7. ‘forced interruption’ means an interruption that (a) occurs when a component is taken out of service immediately, either automatically or as soon as switching operations can be performed, as a direct result of emergency conditions, or (b) is caused by human error or by the improper operation of equipment;

8. ‘frequency’ means the frequency of alternating voltage generated by power system generators;

9. ‘high voltage’ (HV) means a nominal phase-to-phase voltage between the range 11 kilo Volts and 132 kilo Volts both inclusive;

10. ‘LEA’ means the Lesotho Electricity Authority as established in terms of the Act;

11. ‘licensee’ means a generator, transmitter, importer/exporter, distributor or supplier of electricity licensed by the LEA to generate, transmit, import/export, distribute or supply electricity respectively;

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12. ‘low voltage’ (LV) means a nominal phase-to-phase voltage not exceeding 400 Volts

13. ‘medium voltage’ (MV) means a nominal phase-to-phase voltage above LV and below HV

14. ‘planned interruption’ means an interruption that occurs when a component is deliberately taken out of service (by the licensee or its agent) at a selected time, usually for the purpose of construction, preventative maintenance or repair;

15. ‘rural area’ means an area which is not an urban area;16. ‘standard voltage’ means the phase voltage of 230V measured between a

phase conductor and the neutral conductor, or a line voltage of √3 x 230V measured between phase conductors;

17. ‘urban area’ means an area as defined in The Land Act 1979; and18. ‘written notice’ includes a notice submitted in electronic format.

2 Background and Scope

These quality of service and supply standards are issued by the Lesotho Electricity Authority in terms of Sections 22(1) (c) and 22(1) (e) of the Lesotho Electricity Authority Act No. 12 of 2002 with the following conditions:

• For inclusion in generation, transmission and distribution licences (excluding licences for rural electrification) in the electricity supply industry in Lesotho:

• These quality of service and supply standards may be reviewed periodically by the Lesotho Electricity Authority;

• Certain of these standards are not yet operative, and will be put into effect on a date to be determined by the Lesotho Electricity Authority. Relevant standards are identified in the attached schedules; and

• It is not intended at this stage to impose a penalty regime on licensees who fail to meet these performance standards. However the LEA reserves the right to introduce such a system, after consultation with licensees, if licensee performance warrants this;

• A party (customer/licensee) aggrieved by any decision emanating from these standards may appeal to the LEA .Only unresolved disputes that the licensee has been given an opportunity to solve may be referred to the LEA.

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3 Quality of Service Standards

3.1 Service Activities for the Processing of Requests for Supply

The service activities that determine the quality of service in processing requests for supply are provision of quotations and making the service connection. The measures of these services, minimum standards for the services as well as the targeted success in implementing the minimum standards are tabled in Table 1 below.

Table 1: Times for Provision of Quotations and Supply

Service activity

Measure of service standards Minimum standard Target

Quotations to customers

Time taken to provide the customer with a quotation for the cost of providing a supply (once customer has made a written request for supply and has provided all the necessary documentation)

Within 10 working days where existing infrastructure can be used.

Within 1 month where LV network extensions are required

If new networks have to be installed or if a supply is required for industrial or commercial customers, the period for providing a quotation shall be negotiated between the customer and the licensee.

Target percentage success is at least 95%

Provision of supply

Time taken to make a supply available (once all customers obligations have been met, including payment of all monies due)

Within 30 working days where existing infrastructure can be used.

Within 2 months where LV network extensions are required

Within 4½ months where MV network extensions are required

If new networks have to be installed, or if HV extensions are required, or if supply is required for industrial or commercial customers, then the period for requiring the supply shall be negotiated between the customer and the licensee.

Target percentage success is at least 75%

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3.2 Service Activities for Credit Metering

3.2.1 Information Availability

The following information shall be provided to credit meter customers by the licensee at the time of installation of the service connection and any changes subsequently introduced by the licensee shall be made available to customers for inspection at its Service Centers:

1. the scheduled frequency of meter readings;2. the method used to estimate electricity consumption during periods when

no meter readings are taken;3. the amount of the security deposit required for the supply;4. the format of the electricity account;5. the methods of payment of the account and the period allowed for payment

before penalties are applied;6. the location of payment venues and the hours of business;7. the penalties for late payment, for non-payment and for the

disconnection/reconnection process;8. the process to initiate an account query;9. the process that the licensee will follow when it is not possible to gain

access to the customer’s premises or electricity meter;10. the process for dealing with special meter accuracy queries and the fees

charged for accuracy audits;11. the penalties applied in the case of tampering, by-passing of meters or any

other method employed to procure electricity illegally;12.where applicable, the process for recovering any electricity account

arrears;13.where applicable, the voltage transformer/current transformer factors

should be available or calculable.

Table 2 below shows the service standards for frequency of meter readings, disconnections for non-payment & reconnections after payment, account queries and meter accuracy queries.

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Table 2: Minimum Standards for Credit Metering

Service activity


Meter reading Frequency of meter reading for various customers

Customer’s meter should be read at least once in every 3 months

Target average percentage success is 95%

Disconnections/Reconnections for/after non-payment

Periods and time frame for disconnections and reconnections

No disconnection shall be effected until at least 5 working days after the due date for payment stipulated on the account

Commercial and industrial customers shall be given at least 48 hours written notice of an impending disconnection

Disconnections shall only be carried out up to 2 hours before normal closing time of the payment venue

Disconnections shall not be carried out over weekends, public holidays or Fridays (unless normal payment and reconnection facilities are available on Saturday mornings) or on the day before a public holiday

Reconnections shall be effected as promptly as possible; and no later than the first working day after the account has been settled and the reconnection fee has been paid.

Target average percentage success is at least 75%

Disconnections/Reconnections for/after tampering and illegal connection


Disconnection shall be effected immediately without prior notice

Reconnections shall be effected as promptly as possible; and no later than the two working days after applicable fees have been settled and necessary rectification of installation have been done to standards.

Disconnections/Reconnections for/after non adherence to standards


Disconnection may be effected to the premises depending on the nature of non-adherence.

Reconnections shall be effected as promptly as possible; and no later than the first working day after the situation has been rectified accordingly.

Account queries Time to respond to account queries An account query shall be acted upon and be responded to within 5 working days.


Credit meter accuracy queries

Response time to check meter accuracy

A request for meter accuracy checking shall be acted upon and be responded to within 1 month.


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The following notes supplement the table above:

The licensee shall, on request, provide meter reading accuracy checking as a service to customers.

Information on how to obtain the service and any associated costs shall be readily available to customers.

Where applicable, any fee charged for checking the accuracy of a meter shall be refunded if the meter accuracy should prove to be outside the declared limits specified in the supply agreement, or if no such limit is stipulated, then outside the manufacturer’s declared limit.

3.2.2 Payment Venues

Licensee shall ensure that, wherever practical, facilities are provided within or close to urban residential, commercial or industrial areas to afford customers a reasonable opportunity to pay their accounts and to resolve account queries.

3.3 Service Activities for Prepayment Metering

3.3.1 Information AvailabilityThe following information shall be provided to prepayment meter customers by the licensee at the time of installation of the service connection and any changes subsequently introduced by the licensee shall be made available to customers for inspection at its Service Centers:

1. the type of electricity token to be used and how to purchase and use the token;

2. the applicable tariff (which shall also be displayed at the vending station);

3. the location of points of sale of tokens and the hours of business;4. the contact telephone numbers and addresses of the licensee’s service

centers, where service queries and queries concerning the meter can be handled;

5. the process for dealing with special meter accuracy queries and the fees charged for accuracy audits;

6. the applicable fees in the case of tampering, by-passing of meters or any other method employed to procure electricity illegally; and

7. the process for disconnecting of service.

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Table 3 below shows the service standards for provision of vending stations, business hours of vending stations, meter accuracy queries and reconnection of meters.

Table 3: Minimum Standards for Prepayment Metering

Service activity


Provision of vending stations

Number of customers per vending station

Where practical, the licensee shall provide at least one vending station or vending agent for every 2500 customers in urban areas. In rural areas, the licensee shall, where practical, provide at least one vending station or vending agent for each rural system consisting of more than 1000 customers.


Business hours of vending stations

List of vending stations and the actual hours of business of each

List of vending stations and vending agents must be made available to customers at every vending station and vending agent periodically by publication in the local media

Vending stations and vending agents should sell tokens at least during normal working hours on working days, and from 09:00 to 13:00 on weekends and public holidays.


Prepayment meter accuracy queries

Response time to check meter reading accuracy

A request for meter reading accuracy checking shall be acted upon and be responded to within 2 weeks


Reconnection of prepayment meters

Time taken to reconnect prepayment meters

Prepayment meters should be reconnected within 48 hours of receiving a request and the payment of the reconnection fee (except in the case of service removals after tampering has taken place)



The licensee shall, on request, provide meter reading accuracy checking as a service to customers.

Information on how to obtain the service and any associated costs shall be readily available to customers.

Where applicable, any fee charged for checking the accuracy of a meter shall be refunded in the form of units if the meter accuracy should prove to be outside the

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declared limits specified in the supply agreement, or if no such limit is stipulated, then outside the manufacturer’s declared limit.

The licensee shall provide the means to read, to transfer or refund, as appropriate, the amount of unexpended credit due to a customer when a prepayment meter is replaced or removed.

The licensee shall have the right to inspect a prepayment meter at the customer’s premises.

Meters may be inspected if tampering is detected or suspected.

Where reasonable but unsuccessful attempts have been made to gain access to the prepayment meter, the licensee may disconnect the supply after having delivered 24 hours written notice to the customer.

Where access to the premises is unreasonably denied by the customer, immediate disconnection shall be effected.

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3.4 Network Faults

The service activities and standards for the management of network faults are tabled below.

Table 4: Minimum Standards for Handling Network Faults

Service activity


Fault reporting centers

Provision of information on Fault Reporting Centres

Customers to be informed about location and hours of business of fault reporting center(s) by notice at the Licensee’s Service Centers or vending stations (as applicable) and periodically in the local media


Fault reporting process

Information to be supplied to the customer

Information to be requested from the customer

Licensee shall give the reporting customer a fault reference number

The customer reporting a fault shall provide the following information:customer’s name, telephone number (if any), physical address, nature of fault, time fault occurred and meter number.


Forced interruptions

Magnitude of supply restored and time to restore the supply after a forced interruption

30% of interrupted supply within 1,5 hours



100% of interrupted supply within 24 hours


Planned interruptions

Notification Period

Duration of Interruptions

Where possible, at least 48 hours advance notice should be given of any planned interruption

In the case of large commercial or industrial customers, wherever possible, the licensee and customer should mutually agree on planned interruptions

Duration of planned interruptions not to exceed 8 hours for all voltage levels and network types.




Licensee shall provide a 24 hour telephone and internet service to receive reports of faults from customers

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Licensee shall provide a customer service office and internet facility to receive reports of faults from the customers during normal office hours

Licensee shall supply the customer with the telephone number of the fault reporting center and internet address to which faults should be reported

Licensee must classify each fault/customer in an Emergency Priority List (EPL) which dictates the order in which supply after each forced interruption shall be restored.

Licensee may choose to give certain customers on the EPL more than 48 hours notification.

Service standard applies to normal operating conditions. Where abnormal conditions exist, such as adverse weather conditions, then the licensee shall endeavour to keep supply interruptions to an absolute minimum in the circumstances.

The Licensee shall endeavor to keep supply interruptions to an absolute minimum in all cases.

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3.5 Customer Complaints, Enquiries and Requests

The service standards for handling customer complaints, enquiries and requests are tabled in Table 5.

Table 5: Minimum Standards for Managing Customer Complaints, Enquiries and Requests

Service activity


Customer complaints

Time to respond and resolve General complaints received telephonically, through the internet or in person should be handled on a one-stop basis without referral within 1 day.

Written customer complaints should be responded to in writing within five working days and the problem should be resolved within two weeks


Customer enquiries

Time to respond and resolve Enquiries for information and advice received telephonically, through the internet or in person should be handled on a one-stop basis without referral within 1 day.

Where investigative work is required, at least 95% of telephonic enquiries, internet enquiries or queries received in person should be responded to in writing within five working days, and resolved within three weeks


Customer requests

Time to respond and resolve All general customer requests (moving of meters, changing of meters, switching of tariffs etc) should be responded to in writing within two weeks of receipt of the written request


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3.6 Communication Services

Communication services are integral to the business of electricity supply. Table 6 gives the minimum standards for communication services.

Table 6: Minimum Standards for Communication Services

Service activity


Essential communication services

Provision of essential communication services

24 hour telephone service and internet service shall be provided for the reporting of faults and emergencies

A telephone service and internet service for complaints, requests and queries shall be available during normal working hours



Call Handling Response Time All incoming calls to be answered within 15 seconds (4 rings)


3.7 Customer Education

General customer education about electricity supply is encouraged. A licensee must make available and keep updated at least the following information for its customers, and demonstrate that it has taken reasonable measures to inform the specific target audience about:

• Safety issues• Ethos of paying for electricity• Protecting against over voltages and harmonics• Management of disconnections• Efficient Use of Electricity

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4 Quality of Supply Standards

4.1 Frequency

The standard frequency of supply voltage shall be 50Hz.

The limits within which the frequency of supply voltage must be regulated are given in Table 7 below.

Table 7: Minimum Standards for Frequency Regulation

Supply parameter

Measure of supply standards

Minimum standard Target

Compatibility levels

Compatibility levels for the frequency of supply voltage

± 3.0% (±1.5 Hz) For grid networks, the frequency deviation for 99.5% of one year shall be retained

For island networks, the frequency deviation for 95% of one year shall be retained

The following notes supplement the above table:

The assessed levels, to be compared with the compatibility levels shall be the instantaneous measured values of frequency.

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4.2 Voltage Regulation

The limits within which the supply voltage must be regulated are given in Table 8 below.

Table 8: Minimum Standards for Voltage Regulation

Supply parameter

Measure of supply standards Minimum standard Target

Declared voltages

Declared voltage to be supplied to customers

For customers supplied at LV, the declared supply voltage shall be the standard voltage.

For customers supplied at other voltage levels, the magnitude of the declared voltage shall be as specified in the supply agreement.

Unless otherwise specified in the supply agreement, the declared voltage shall be the nominal voltage.

For grid networks, the voltage level shall be retainedfor 99.5% of one year

For island networks, the voltage level shall be retained for 95% of one year.

Compatibility levels

Compatibility levels for the magnitude of supply

Voltage level(V)

Compatibility level (%)

≤400 ±10>400 ± 5

For grid networks, the voltage deviation for 99.5% of one year shall be retained

For island networks, the voltage deviation for 95% of one year shall be retained

The following notes supplement the above table:

The assessment period is a minimum of 7 continuous days.

Measurements shall be taken at the extremities (near and far ends) of feeders.

The assessed levels, which are to be compared with the compatibility levels, are the highest and lowest daily values over the full assessment period.

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4.3 Voltage Unbalance

Voltage unbalance (UB) defines the degree to which the three phases of the electrical supply are not identical either in magnitude or displacement (or both). UB can be described in terms of the contribution of zero sequence voltages and the contribution of negative sequence voltages. Only the contribution of the negative sequence voltages are given because this is the relevant component when considering the impact on equipment connected to the system.

Voltage unbalance is usually expressed in percentage and is (simplistically) given:

UB = (Deviation between highest and lowest phase voltage) ÷ (Average Voltage of three phases) × 100

Or more accurately UB is given by:

UB = Vn ÷ Vp × 100

Where Vn is the negative sequence voltage, in voltsVp is the positive sequence voltage, in volts

Alternatively, simultaneous measurement of the three r.m.s phase-to-phase voltages can be used to calculate the unbalance as:

UB = (1-(3-6β)½ ÷ 1+(3-6β)½)½ × 100

Where β =((V12)4 + (V23)4+ (V31)4) ÷ ( (V12)2 + (V23)2 + (V31)2 )2

and where V12 represents the phase-to-phase voltage between phases 1 and 2 and similarly for V23 and V31.

The compatibility level for UB on LV, MV and HV three-phase networks shall be 2%.

On networks where there is a predominance of single-phase or two-phase customers, a compatibility level of 3% may be applied.

The assessment period is a minimum of 7 continuous days.

The highest of the assessed 95% weekly values over the full measurement period shall be compared with these compatibility levels.

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4.4 Voltage Harmonics and Interharmonics*

The compatibility levels for voltage harmonics and interharmonics relate to quasi-stationary or steady state harmonic values and are specified for both long-term effects and very short-term effects

The long-term effects relate mainly to thermal effects on cables, transformers, motors, capacitors etc.Very short-term effects relate mainly to disturbing effects on electronic devices that may be susceptible to harmonic distortion. The effects of transients are excluded.

The highest of the assessed 95% weekly values over the full measurement period shall be compared with the compatibility levels in the table.

The compatibility levels for harmonic voltages are given in Annex A

* Standard to be implemented in future

4.5 Voltage Flicker*

Voltage flicker is the modulation of the supply voltage amplitude that can be observed as a fluctuation of the light intensity of electric lighting.

For LV and MV networks, the compatibility level for short-term flicker severity (Pst) shall be 1.0, and the compatibility level for long-term flicker shall be (Plt) shall be 0.8.

The highest of the assessed 95% weekly Plt values over the full measurement period shall be compared with this compatibility level.

* Standard to be implemented in future

4.6 Inter-utility Interfaces

General:Individual generation units’ capacity output verification test must be done by the utility concerned and be witnessed by other stakeholders at least once a year in terms of SAPP ‘Agreement Between Operating Members.’

Table 9 below gives the minimum standards of supply parameters between interfacing utilities.

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Table 9: Minimum Standards of Supply Parameters Between Interfacing Utilities

Supply parameter

Measure of supply standards Minimum standard Target

Declared voltage supply at PCC

Voltage supplied by generators to transmission grid

Nominal voltage +5%of Nominal voltage

Declared generation frequency at PCC

Service level deviation from 50Hz Maintain acceptable deviation levels per SAPP CPS 1 and CPS 2

Deviation between 49.85 and 50.15Hz for 95% per month

Declared reactive power at PCC

Capability to produce or absorb reactive power at PCC

Within tested generator’s capability

Between ± 0.85 PF Lagging or Leading

Operating reserve capacity at PCC

Capability to service system load that is less or equals 65MW

Hydro quick and spinning reserve service obligation as prescribed by SAPP

10% of 72MW being installed capacity

Generation schedules dispatch through AGC

Accuracy level between schedules and actual delivery

Maintain required capacity for load requirements that are less or equals 72MW

Within 5% average deviation per month

Protection relay co-ordination at PCC

Integrity on system grading, selected schemes, settings, etc

To be mutually agreed between utilities

Generator black start facility

Capability to synchronize hydro units to diesel power during an incident or drill

Drills to be carried out at least twice a year using resources within plant

Synchronization within 1 hour per each incident or drill

*Planning levels for harmonic voltage on HV and EHV systems

See Annex B * Standard to be implemented in future

The operating guide lines of SAPP shall take precedence over the above table.

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Annex A

Compatibility levels for harmonic voltages (Expressed as a percentage of the fundamental voltage of LV and MV power

systems)

1 2 3 4 5 6Odd harmonics

Not multiples of three Multiples of three(See note)

Even harmonics

OrderH

Magnitude%

Orderh

Magnitude%

Orderh

Magnitude%

5 6 3 5 2 27 5 9 1.5 4 111 3.5 15 0.5 6 0.513 3 21 0.3 8 0.517 ≤ h ≤ 49

{2.27 x (17/h)} – 0.27

21 ≤ h ≤ 45

0.2 10 ≤ h ≤ 50

{0.25 x (10/h)} + 0.25

NOTE – The levels given for odd harmonics that are multiples of 3 apply to zero sequence harmonics. Also on a three-phase network without a neutral conductor or without load connected between phase and earth, the actual values of the third and ninth harmonics might be much lower than the compatibility levels depending on the UB value of the system.

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Annex B

Recommended planning levels for harmonic voltage on HV and EHV systems

Indicative values of planning levels for harmonic voltage (In % of the rated voltage of HV and EHV power systems)

1 2 3 4 5 6Odd harmonics non multiple of 3

Odd harmonics multiple of 3

Even harmonics

OrderH

Harmonic voltage

%HV-EHV

Orderh

Harmonic voltage

%HV-EHV

Orderh

Harmonic voltage

%HV-EHV

5 2 3 2 2 1,57 2 9 1 4 111 1,5 15 0,3 6 0,513 1,5 21 0,2 8 0,417 1 >21 0,2 10 0,419 1 12 0,223 0,7 >12 0,225 0,7>25 0,2 +

0,5 x 25/hrTotal harmonic distortion (THD): 3% in HV networks

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Contact Person

The Director: Technical DepartmentLesotho Electricity Authority

6th Floor, Moposo HouseKingswayMaseruLesotho

Tel: 2231 2479

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Documents

Electricity Quality of Service and Supply Standards · 12.‘low voltage’ (LV) means a nominal phase-to-phase voltage not exceeding 400 Volts 13.‘medium voltage’ (MV) means