Post on 28-Nov-2014
04/09/23 Module Two 1
SUBSTATION COMMISSIONING COURSE
MODULE TWO
SWITCHGEAR ASSEMBLIESTESTING PROCEDURES
04/09/23 Module Two 2
INTRODUCTION
• The electrical commissioning and acceptance testing of electric power systems is essential for the energization of any electrical system for the first time.
04/09/23 Module Two 3
INTRODUCTION
Module Two:• Introduce the NETA acceptance
testing procedures– Visual and mechanical
inspections– Electrical tests– Assessment of test results
• Test equipment operation & hands on testing
• Adopting safe work practices
04/09/23 Module Two 4
INTRODUCTION
By the end of MODULE ZERO:• Perform acceptance testing
procedure for switchgear assemblies
• Operate insulation and dielectric test equipment
• Operate Digital Low Resistance Ohmmeter (DLRO)
• Apply safe work practices• Analyze test values• Complete test forms
04/09/23 Module Two 5
ELECTRICAL TESTING
• Majority of testing is to check the insulation system integrity
• Types of Solid Insulation testing:– Insulation Resistance test
• Prelude for the Dielectric Withstand– Dielectric Withstand test
• Survivability for high voltage spikes– Switching, lightning induced over
voltages and transients
04/09/23 Module Two 6
TESTING
Insulation Testing:• Insulation
Resistance
DC Insulation Resistance Test• Conducted at 100% of
operating stress level• AC RMS voltage x 1.414• Voltage applied < 1000 V/s• Voltage held for 1 minute• If “pass”, proceed to dielectric
withstand test
– NOTE: Voltage level specified is higher than NETA test voltage
04/09/23 Module Two 7
TESTING
Insulation Testing:• Insulation
Resistance
Test Volt. Calculation example:
Nameplate Rated voltage: 5 kV
Ø – gnd voltage = 5 kV / 1.732
= 2.887 kV
Crest Voltage = 2.9 kV x 1.414
= 4.1 kV
Test Voltage = 4.1 kV
04/09/23 Module Two 8
ELECTRICAL TESTING
04/09/23 Module Two 9
TESTING
Insulation Testing:• Insulation
Resistance
IR Test Procedure:• Isolate equipment• Prepare the DUT• Prepare the Test set• Apply test voltage
04/09/23 Module Two 10
TESTING
Insulation Testing:• Insulation Resistance
Test Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Isolate Equipment / DUT:• Apply isolation / lock-out /
grounding procedure• Obtain test and work
permit• Install DANGER HIGH
VOLTAGE – TESTING IN PROGRESS warning signs
• Install barrier tape or high visibility rope barrier
04/09/23 Module Two 11
TESTING
04/09/23 Module Two 12
TESTING
Insulation Testing:• Insulation Resistance
Test Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Prepare the DUT:• Disconnect all incoming
and outgoing cables– Maintain adequate
clearance• Remove primary fuses
from VT / PT’s and CPT• Disconnect surge arrestors
04/09/23 Module Two 13
TESTING
Insulation Testing:• Insulation Resistance
Test Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Prepare the Test Set:• Functional check
– Battery Level– Calibration date– Short circuit test– Recording paper
• Link computer software• Use grounded plug / GFI if
AC powered
04/09/23 Module Two 14
TESTING
Insulation Testing:• Insulation Resistance
Test Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Apply test voltage:• Apply test voltage• Test to the desired time
interval• Discharge / ground tested
phase before changing / removing connections
• Review test data• Proceed to dielectric test
IF results are satisfactory !
04/09/23 Module Two 15
TESTINGNETA Insulation Resistance Test Voltage level
04/09/23 Module Two 16
TESTING
Insulation Testing:• Dielectric Withstand
Dielectric Withstand Test• AC / DC depending on class• Factory Test + 200% of rated
voltage• Field acceptance test @ 75% of
Factory level
04/09/23 Module Two 17
ELECTRICAL TESTING
Insulation Testing:• Dielectric Withstand
AC Dielectric Withstand Test• Rated power frequency, 60 Hz • Voltage applied at a rate
< 1000 V per second• Voltage held for 1 minute
CAUTION: AC Hipot can be a destructive test
04/09/23 Module Two 18
ELECTRICAL TESTING
Insulation Testing:• Dielectric Withstand
Factory AC Dielectric Withstand Test as per IEEE C37.20.2
Rated max Volts Test Volts
(kV rms) (kV rms)
4.76 14.0
8.25 27.0
15.0 27.0
27.0 38.0
38.0 60.0
04/09/23 Module Two 19
ELECTRICAL TESTING
Phase A Hot: AC Hipot, Breaker Connected & Closed
04/09/23 Module Two 20
ELECTRICAL TESTING
Phase B Hot: AC Hipot, Breaker Connected & Closed
04/09/23 Module Two 21
ELECTRICAL TESTING
Phase C Hot: AC Hipot, Breaker Connected & Closed
04/09/23 Module Two 22
ELECTRICAL TESTING
Phase A Hot: AC Hipot, Breaker Connected & Opened
04/09/23 Module Two 23
ELECTRICAL TESTING
Phase B Hot: AC Hipot, Breaker Connected & Opened
04/09/23 Module Two 24
ELECTRICAL TESTING
Phase C Hot: AC Hipot, Breaker Connected & Opened
04/09/23 Module Two 25
TESTING
Insulation Testing:• Dielectric Withstand
60 Hz
Dielectric Test Procedure:• Isolate equipment• Prepare the DUT• Prepare the Test set• Apply test voltage
04/09/23 Module Two 26
TESTING
Insulation Testing:• Dielectric Withstand Test
Procedure - 60 Hz– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Isolate Equipment / DUT:• Apply isolation / lock-out /
grounding procedure• Obtain test and work
permit• Install DANGER HIGH
VOLTAGE – TESTING IN PROGRESS warning signs
• Install barrier tape or high visibility rope barrier
04/09/23 Module Two 27
TESTING
04/09/23 Module Two 28
TESTING
Insulation Testing:• Dielectric Withstand Test
Procedure – 60 Hz– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Prepare the DUT:• Disconnect all incoming
and outgoing cables– Maintain adequate
clearance• Remove primary fuses
from VT / PT’s and CPT• Disconnect surge arrestors• Ensure equipment is
grounded
04/09/23 Module Two 29
TESTING
Insulation Testing:• Dielectric Withstand Test
Procedure – 60 Hz– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Prepare the Test Set:• Perform functional check
– Spark Gap test– Recording paper
• Link computer software• Use grounded plug / GFI• Ground test set to
equipment ground
04/09/23 Module Two 30
TESTING
Insulation Testing:• Dielectric Withstand Test
Procedure – 60 Hz– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test voltage
Apply test voltage:• Apply test voltage• Test to the desired time
interval• Discharge / ground tested
phase before changing / removing connections
• Review test data
04/09/23 Module Two 31
TESTING
Dielectric Withstand Test – 60 Hz• Some manufacturer recommend Low Frequency
withstand voltage VS Power Frequency• Field test voltage levels are the same• Field test voltage at 75% of factory test voltage• DC Hipot is not recommended but not prohibited
04/09/23 Module Two 32
TESTING
Dielectric Withstand Test – DC• Will not be presented• Included in the manual for the sake of
completeness
04/09/23 Module Two 33
TESTING
Low Resistance test• Measures bolted connection resistance
– Bus bar to bus bar resistance– Bus bars to cable resistance
• DC test at constant 100 ADC or higher• Joints must be torque to specified force (ft-lbs)• Values are compared to similar joints• High reading joints are inspected / retorque /
reassembled and retested
04/09/23 Module Two 34
TESTING
Low Resistance test• Access to main bus compartment required
– Remove metal barriers for access– Insulating boots for bolted joints removed
• Measure on a per phase basis• Resistance calculated based on Ohm’s Law
– Example: – 1 mV across joint equates to 10 μΩ– (1 X 10-3 V) / (1 x 102 A) = 1 x 10-5 = 10 x 10-6
04/09/23 Module Two 35
TESTING
04/09/23 Module Two 36
TESTING
Low Voltage Testing:• Low Resistance
Test Procedure
Low Resistance test:• Isolate equipment• Prepare the DUT• Prepare the Test set• Apply test current
04/09/23 Module Two 37
TESTING
Low Test Resistance Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test current
Isolate Equipment / DUT:• Apply isolation / lock-out /
grounding procedure• Obtain test and work
permit• Install DANGER HIGH
VOLTAGE – TESTING IN PROGRESS warning signs
• Install barrier tape or high visibility rope barrier
04/09/23 Module Two 38
TESTING
04/09/23 Module Two 39
TESTING
Low Test Resistance Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test current
Prepare the DUT:• Ensure equipment is
grounded
04/09/23 Module Two 40
TESTING
Low Test Resistance Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test current
Prepare the Test Set:• Perform functional check
– Calibration resistor• Use grounded plug / GFI
04/09/23 Module Two 41
TESTING
Low Test Resistance Procedure– Isolate equipment– Prepare the DUT– Prepare the Test set– Apply test current
Apply test current:• Apply test current• Measure resistance of all
bolted connections• Measure resistance of all
breaker connections– Sliding contacts– Main contacts
• Review test data
04/09/23 Module Two 42
SAFETY AWARENESS & PRACTICE
• HV testing is an electrical shock potential• Test set operators must:
– be aware of the hazards involved in performing the task
– take the required safety precautions and restrict access to anyone not involved in the testing process
– be properly trained in the equipment operations – recognize and avoid the hazards– be trained in safe work practices and procedures
04/09/23 Module Two 43
SAFETY AWARENESS & PRACTICEQualified person
A qualified person shall be trained and knowledgeable of the construction and operation of equipment or a specific work method, and be trained to recognize and avoid the electrical hazard that might be present with respect to
that equipment or work method. Such persons shall also be familiar with the proper use of special precautionary techniques, personal protective equipment, insulating and shielding material, and insulating tools and test
equipment.
04/09/23 Module Two 44
Qualification of Qualified Person1. Basic understanding of
electricity
2. Working knowledge of test equipment and hazards with the test and equipment
3. Understand approach distances
4. Trained is safe work practices and procedures
5. Understand the factors affecting severity of electrical shock
6. Know the effects of current to the body
7. Trained on releasing a victim from energized circuit
8. Trained not to contact a device under test
9. Understand that enclosure and test equipment must be grounded
10. Know that DUT must be discharge before changing / removing any connections
04/09/23 Module Two 45
SAFETY AWARENESS & PRACTICE
• Engineering controls and work practices primary factors for safeguarding against risk of injury
• PPE is not an alternative to safe work practices
04/09/23 Module Two 46
SAFETY AWARENESS & PRACTICE
Resources:• IEEE Standard 510 – 1983,
Recommended Practice for Safety in High Voltage & High Power Testing
• NEMA Standard Publication SG 10 – 2008, Guide to OSHA and NFPA 70E Safety Requirements When Servicing and Maintaining Medium-Voltage Switchgear and Circuit Breakers Rated above 1000 Volts.
04/09/23 Module Two 47
NETA STANDARD
3. NETA Acceptance Testing Procedures 3.1 Visual and Mechanical Inspection 3.2 Electrical Test 3.3 Test values analysis 3.3.1 Visual and Mechanical 3.3.2 Electrical
04/09/23 Module Two 48
TEST SET MANUALS
15 KV Insulation Resistance Test set
AC High Potential Test set DC High Potential Test set Digital Low Resistance Test set
04/09/23 Module Two 49
TEST FORM
Switchgear Inspection Check List Form Bus Resistance Test Form Bus Insulation Test Form
04/09/23 Module Two 50
04/09/23 Module Two 51
04/09/23 Module Two 52