2. Contents
• Eskom’s 5 Life Saving Rules
• Power Plant Maintenance Department
Voltage Regulators and Reclosers
• Standards Implementation Environment
Different Forums and Processes
Inspections and Investigation
Non-Conformances
• Line Hardware – CNC and SI
• Control Plant Maintenance - Metering
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3. Eskom’s 5 Life Saving Rules
• Open, isolate, test, earth, bond and/or insulate before touch
• Hook up at heights
• Buckle up during vehicle trips
• No one is to work under the influence of alcohol or/and drugs
• Having a valid worker’s permit
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4. 4
Departments
Departments Visited Next Departments
Power Plant Maintenance
(PPM)
CPM - DC
Standards
Implementation (SI)
CPM - Telecontrol
Customer Network Centre
(CNC)
CPM - Mainly Protection
Control Plant
Maintenance - Metering
8. Power Plant Maintenance
• Consists of two sub departments : Plant and Auxiliaries.
• Preventative maintenance, repairs, testing, build and manufacturing
service, within an operating unit.
.
8
Plant
Supervisor: Noxolo Mabula
Auxiliaries
Supervisor: Ronald Anderson
Transformers Cables
Tap Changers Switchgear - Reclosers
Oil sampling Voltage Regulators
Infrared Capacitor Banks
10. The Voltage Regulator
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• A Voltage Regulator can continuously monitor the output voltage
and automatically adjust itself by changing taps until the desired
voltage is obtained .
11. 11 11
How does a Voltage Regulator work?
A Regulator is an auto transformer with the ability to raise or lower
the primary or system voltage
A single-phase regulator is represented by the autotransformer in
the figure below.
Voltage Regulator Diagram
12. 12
How does a Voltage Regulator work?
Polarity reversing is achieved via a reversing switch. An on-load
tap-changer connects a variable number of turns of the series
winding into the circuit, thereby allowing small increments of
voltage change.
18. How is it implemented?
• Two or three single-phase regulators banked together make it possible
to regulate the voltage of a three-phase system.
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Closed-Delta Open-Delta
3 Voltage Regulators 2 Voltage Regulators
15% Regulation of Input
Voltage
10% Regulation of Input
Voltage
Mostly used in ECOU Cost effective
19. Connection Configuration
Two or three single-phase regulators banked together make it possible to
regulate the voltage of a three-phase system.
Closed Delta Implementation Open Delta Implementation
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21. Operating sequence to put a regulator bank
back in service - SWP 34-1436
1. Remove all earths after maintenance etc.
2. Check regulator bypass links to be closed.
3. Close regulator incoming links.
4. Ensure that regulators is on neutral tap.
5. Close regulator bank outgoing links.
6. Open regulator bank bypass links.
7. Put regulator on auto
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23. Reclosers
• Reclosers are intelligent circuit breakers that operate differently
depending on the fault and situation of the fault.
• They utilize Inverse Definite Minimum Time (IDMT) curves to
determine the time for each trip with a given fault current.
• ECOU are using two types:
• Nu-Lec Industries a company of Schneider Electric.
• The FlexVue is the predecessor of the Nu-Lec.
• Other:
• Travida
• McGraw-Edisson owned by Cooper Industries,
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24. NU-LEC
• The N-Series remotely controlled and monitored automatic circuit pole
mounted recloser consist of an N-Series automatic circuit recloser
(ACR) combined with a Controller Unit.
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ACR Control Unit
25. Solenoids And Capacitors
• The breaker operates with the use of a trip and close coils.
• These solenoids are energized by corresponding trip and close
capacitors housed behind the control card within the control console.
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Close Cap Trip Cap
Close Coil
Open Coil
26. Fault Operations
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Sensitive Earth Fault Lower than usual fault current, resistive
fault to earth caused by a tree branch or
contact with an animal -15A.
Earth Fault One or more phases to ground, or may occur
between phases - 40A.
Over Current When the system is drawing over the rated
safe current for the equipment - 60A
Loss Of Phase By losing one of more of the phases in the
network (Unbalanced voltage level),
Over Voltage System is operating above rated voltage
Under Voltage System is operating below rated voltage
27. IDMT Curve
• Reclosers utilize Inverse Definite Minimum Time (IDMT) curves to
determine the time for each trip with a given fault current.
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28. Circuit Breaker
• 6 Current Transformer and Capacitive Voltage transformers.
• 3 on source and 3 on load side; these are protection class
measurement devices.
• The readings are sent to the CC via a control cable, this cable leaves
the Circuit breaker from the bottom of the tank via the Switch Control
Entry Module (SCEM) card.
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29. FlexVue
• The FlexVue N-series ADVC Controller is produced by Schneider
Electric and has a similar design that the NU-LEC.
• The FlexVue is purely modular with limited access to individual
components.
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30. Remote Access
• The N-Series operating panel with complete control system consist off
a modem, radio, power unit and protection devices.
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Communication Devices -Radio and Modem
33. Standards Implementation
17 March 2014 – 4 April 2014
Supervisor: Henry Jordaan
•Technical Change Implementation Forum
•Non – Conformances
•Investigation
•Material Inspections
34. Standards Implementation
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• SI is responsible for the development and investigation of standards, operations,
procedures, task manuals ,buyer’s guides and specifications.
• This includes inspections and investigations of incidents, contractor material (new
projects), line quality and technical assessments to ensure that they comply with the
ESKOM standards.
Standards
Implementation
Incident
Investigations Technical
Assessments
Warehouse
Stock
Dummy
Lines
Material
Evaluations
Contractors Tenders
Non Conformances
35. Technical Change Implementation Forum
• TCIF is a Forum mandated to support Power Delivery Engineering,
DistributionTransmission and Telecomms with implementation of
technical standards.
• The Forum serves as a link between Operating Units, Centres of
Excellence and Study Committees ensuring that national standards
are applied appropriately within OUs and to highlight areas of OU
operations that are not adequately defined by existing standards.
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TCIF
Implementation of technology standards in OU’s
Any changes to technical standards are implemented in all
business areas of the OU.
Identify opportunities for technology development
Manage investigations into technology applications.
36. Non-Conformance Report
• Directly issue any non-conformance regarding a certain product which
fails or disregards a specific standard of specification.
• Issued to the manufacturers to notify them of the non conformance.
• Consists:
• Root Cause
• Immediate Correction
• Action to Prevent Recurrence
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37. NCR – Tombo Substation
Non-Conformance Standards & Specifications
ABB 132kV Breaker cracked rubber
boot.
DSP34-1687
ACTOM Dog box Breaker Leaks DSP34-1687 REQUIREMENTS FOR
11kV, 22kV AND 33kV OUTDOOR
KIOSK TYPE SWITCHGEAR
ABB Breaker corroding handle DSP- 32 1166 SPECIFICATION FOR
OUTDOOR CIRCUIT-BREAKERS
22kV Isolators leakage ESP 32-536 SPECIFICATION FOR
HIGH VOLTAGE OUTDOOR
DISCONNECTORS AND EARTHING
SWITCHES
NEC/NER/Aux TRFR 22kV sealing
problems
DSP 34-1690 Specification for
combined three-phase NEC’s with
NER’s and Aux power transformers
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38. NCR – Tombo Substation
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NEC Bent Cubicle
Sealing defects
Moisture
42. Soil Resistivity Survey
• The resistivity of soil is dependent on its composition and moisture
content.
• Significant impact on the resistance of an earth electrode according to
DST_34-1985.
• Impacts the potential gradients at the soil surface during fault current
discharge through the earth electrode- Step Potential.
• Resistance readings from 0,01 Ω to 1999 Ω shall be obtainable
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43. Wenner Measuring Method
• Assumption that the soil in which the measurement is made is
homogenous
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Average resistivity to depth D: ρ = 2πaR (Ωm)
a - test probe spacing.
R -tester readings in ohms.
D - eighty percent of the probe spacing (i.e. D = 0,8 × a).
57. Substation Routines
• In order to maintain the widely spread ECOU distribution network,
monthly substation routines are implemented within the CNC
department.
• DC supply inspection, Trip Counters and Oil levels are checked.
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59. CPM Metering
• Metering data is directly related to the revenue of Eskom and to
safeguard this revenue, rules need to be put in place for the access to
a metering installation, the meter and the metering data.
• CTVT Commissioning
• Occasional Data Capturing
• Large Power User installations (LPU)
• Stats and Tariff metering in Substations
• Meter testing and calibration
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60. CTVT Panels
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A primary plant device that comprises a combination of current and voltage
transformers for metering purposes .
CTVT panels are commissioned for Large Power Users for eg. a 350kVA plant.
61. Insulation Test : DPC_240-55197966
1) The primary-to-earth and primary-to-secondary insulation > 2 MΩ/kV
2) The secondary-to-earth insulation resistance shall not be < 20 MΩ
• CTVT Point : Lukhanji Bricks SADA507
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CT Insulation test Red Phase White Phase Blue Phase
Primary to earth
(5kV): 5.1 GΩ 5.2 GΩ 6 GΩ
Primary to secondary
(5kV): 23 GΩ 27 GΩ 24 GΩ
Secondary to earth
(500V): 5.9 GΩ 5.9 GΩ 5.9 GΩ
62. Primary Injection: DPC_240-55197966
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Site: Bisho SAPD Shooting Range
Objective: Repair and commission Vandalized CTVT point.
Ratio 10: 1
Injection
Red phase
White
phase Blue phase
Primary current (A): 10 10 10
Secondary current: 0.999 1.002 1.012
Calculated % error -0.10 0.20 1.19
Safe Working Guide: MET06
64. Calibration and testing
• Load tests – Verify performance of meter under different loads
• Creep test – To verify whether the meter can detect no load.
• Starting test - Can the meter operate under small load.
• Register test – Injecting a certain kwh and monitor the meter.
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65. 65
Programming
TransducerProgramming
Meters need to be programmed to set up the load profile and ratings for
the particular site.
Transducer needs to be programmed with V, I Q and P output ratings for
substation use – Remote Terminal Unit for Telecontrol.
