NETA ATS
7.1 Switchgear and Switchboard
Assemblies
A. Visual and Mechanical
Inspection:
- Compare equipment nameplate data with drawings and specifications.
- Inspect physical and mechanical condition.
- Inspect anchorage, alignment, grounding, and required area clearances.
- Verify the unit is clean and all shipping bracing, loose parts, and documentation shipped
inside cubicles have been removed.
- Verify that fuse and circuit breaker sizes and types correspond to drawings and coordination
study as well as to the circuit breaker’s address for microprocessor-communication packages.
- Verify that current and voltage transformer ratios correspond to drawings.
- Verify that wiring connections are tight and that wiring is secure to prevent damage during
routine operation of moving parts.
- Inspect bolted electrical connections for high resistance using one or more of the following
methods:
- Use of a low-resistance ohmmeter in accordance with Section 7.1.B.1.
- Verify tightness of accessible bolted electrical connections by calibrated torquewrench
method in accordance with manufacturer’s published data or Table 100.12.
- Perform thermographic survey in accordance with Section 9.
- Verify operation and sequencing of interlocking systems.
- Verify appropriate lubrication on moving current-carrying parts and on moving and sliding
surfaces.
- Inspect insulators for evidence of physical damage or contaminated surfaces.
- Verify correct barrier and shutter installation and operation.
- Exercise all active components.
- Inspect mechanical indicating devices for correct operation.
- Verify that filters are in place and vents are clear.
- Perform visual and mechanical inspection of instrument transformers in accordance with
Section 7.10.
- Perform visual and mechanical inspection of surge arresters in accordance with Section 7.19.
- Inspect control power transformers.
- Inspect for physical damage, cracked insulation, broken leads, tightness of
connections, defective wiring, and overall general condition.
- Verify that primary and secondary fuse or circuit breaker ratings match drawings.
- Verify correct functioning of drawout disconnecting contacts, grounding contacts, and
interlocks.
B. Electrical Tests:
- rm resistance measurements through bolted electrical connections with a low-resistance
ohmmeter, if applicable, in accordance with Section 7.1.A.8.1.
- Perform insulation-resistance tests on each bus section, phase-to-phase and phase-to-ground,
for one minute in accordance with Table 100.1.
- Perform a dielectric withstand voltage test on each bus section, each phase-to-ground with
phases not under test grounded, in accordance with manufacturer’s published data. If
manufacturer has no recommendation for this test,
- *Perform insulation-resistance tests on control wiring with respect to ground. Applied
potential shall be 500 volts dc for 300-volt rated cable and 1000 volts dc for 600-volt rated
cable. Test duration shall be one minute. For units with solid-state components or control
devices that can not tolerate the applied voltage, follow the manufacturer’s recommendation.
- Perform electrical tests on instrument transformers in accordance with Section 7.10.
- Perform ground-resistance tests in accordance with Section 7.13.
- Test metering devices in accordance with Section 7.11.
- Control Power Transformers
- Perform insulation-resistance tests. Perform measurements from winding-to-winding
and each winding-to-ground. Test voltages shall be in accordance with Table 100.1
unless otherwise specified by the manufacturer.
- Perform a turns-ratio test on all tap positions.
- Perform secondary wiring integrity test. Disconnect transformer at secondary
terminals and connect secondary wiring to a rated secondary voltage source. Verify
correct potential at all devices.
- Verify correct secondary voltage by energizing the primary winding with system
voltage. Measure secondary voltage with the secondary wiring disconnected.
- Verify correct function of control transfer relays located in the switchgear with
multiple control power sources.
- Voltage Transformers
- Perform secondary wiring integrity test. Verify correct potential at all devices.
- Verify secondary voltages by energizing the primary winding with system voltage.
- Perform current-injection tests on the entire current circuit in each section of switchgear.
- Perform current tests by secondary injection with magnitudes such that a minimum
current of 1.0 ampere flows in the secondary circuit. Verify correct magnitude of
current at each device in the circuit.
- *Perform current tests by primary injection with magnitudes such that a minimum of
1.0 ampere flows in the secondary circuit. Verify correct magnitude of current at each
device in the circuit.
- Perform system function tests in accordance with ANSI/NETA ECS.
- Verify operation of cubicle switchgear/switchboard space heaters.
- Perform phasing checks on double-ended or dual-source switchgear to insure correct bus
phasing from each source.
- Perform electrical tests of surge arresters in accordance with Section 7.19.
C. Test Values – Visual and
Mechanical
- Compare bolted connection resistance values to values of similar connections. Investigate
values which deviate from those of similar bolted connections by more than 50 percent of the
lowest value. (7.1.A.8.1)
- Bolt-torque levels shall be in accordance with manufacturer’s published data. In the absence
of manufacturer’s published data, use Table 100.12. (7.1.A.8.2)
- Results of the thermographic survey shall be in accordance with Section 9. (7.1.A.8.3)
D. Test Values – Electrical
- Compare bolted connection resistance values to values of similar connections. Investigate
values which deviate from those of similar bolted connections by more than 50 percent of the
lowest value.
- Insulation-resistance values of bus insulation shall be in accordance with manufacturer’s
published data. In the absence of manufacturer’s published data, use Table 100.1. Values of
insulation resistance less than this table or manufacturer’s recommendations should be
investigated. Dielectric withstand voltage tests shall not proceed until insulation-resistance
levels are raised above minimum values.
- If no evidence of distress or insulation failure is observed by the end of the total time of
voltage application during the dielectric withstand test, the test specimen is considered to
have passed the test.
- Minimum insulation-resistance values of control wiring shall not be less than two megohms.
- Results of electrical tests on instrument transformers shall be in accordance with Section 7.10.
- Results of ground-resistance tests shall be in accordance with Section 7.13.
- Accuracy of metering devices shall be in accordance with Section 7.11.
- Control Power Transformers
- Insulation-resistance values of control power transformers shall be in accordance with
manufacturer’s published data. In the absence of manufacturer’s published data, use
Table 100.1. Values of insulation resistance less than this table or manufacturer’s
recommendations should be investigated.
- Turns-ratio test results shall not deviate by more than one-half percent from either the
adjacent coils or the calculated ratio.
- Secondary wiring shall be in accordance with design drawings and specifications.
- Secondary voltage shall be in accordance with design specifications.
- Control transfer relays shall perform as designed.
- Voltage transformers
- Secondary wiring shall be in accordance with design drawings and specifications.
- Secondary voltage shall be in accordance with design specifications
- Current-injection tests shall prove current wiring is in accordance with design specifications.
- Results of system function tests shall be in accordance with ANSI/NETA ECS.
- Heaters shall be operational.
- hasing checks shall prove the switchgear or switchboard phasing is correct and in
accordance with the system design.
- Results of electrical tests on surge arresters shall be in accordance with Section 7.19.
NETA MTS
7.1 Switchgear and Switchboard
Assemblies
A. Visual and Mechanical
Inspection:
- Inspect physical, electrical, and mechanical condition.
- Inspect anchorage, alignment, grounding, and required area clearances.
- Prior to cleaning the unit, perform as-found tests, if required.
- Clean the unit.
- Verify that fuse and/or circuit breaker sizes and types correspond to drawings and
coordination study as well as to the circuit breaker address for microprocessorcommunication
packages.
- Verify that current and voltage transformer ratios correspond to drawings.
- Verify that wiring connections are tight and that wiring is secure to prevent damage during
routine operation of moving parts.
- Inspect bolted electrical connections for high resistance using one or more of the following
methods:
- Use of a low-resistance ohmmeter in accordance with Section 7.1.B.1.
- Verify tightness of accessible bolted electrical connections by calibrated torquewrench
method in accordance with manufacturer’s published data or Table 100.12.
- Perform thermographic survey in accordance with Section 9.
- Confirm correct operation and sequencing of electrical and mechanical interlock systems.
- Attempt closure on locked-open devices. Attempt to open locked-closed devices.
- Make key exchange with all devices included in the interlock scheme as applicable.
- Use appropriate lubrication on moving current-carrying parts and on moving and sliding
surfaces.
- Verify correct barrier and shutter installation and operation.
- Exercise all active components.
- Inspect mechanical indicating devices for correct operation.
- Verify that filters are in place and/or vents are clear.
- Perform visual and mechanical inspection of instrument transformers in accordance with
Section 7.10.
- Perform visual and mechanical inspection of surge arresters in accordance with Section
7.19.
- Inspect control power transformers.
- Inspect for physical damage, cracked insulation, broken leads, tightness of
connections, defective wiring, and overall general condition.
- Verify that primary and secondary fuse ratings or circuit breakers match drawings.
- Verify correct functioning of drawout disconnecting and grounding contacts and
interlocks.
- Perform as-left tests.
B. Electrical Tests:
- performrm resistance measurements through bolted electrical connections with a low-resistance
ohmmeter, if applicable, in accordance with Section 7.1.A.7.1.
- Perform insulation-resistance tests on each bus section, phase-to-phase and phase-to-ground,
for one minute in accordance with Table 100.1.
- Perform a dielectric withstand voltage test on each bus section, each phase-to-ground with
phases not under test grounded, in accordance with manufacturer’s published data. within
the absence of manufacturer’s published data, use Table 100.2. The test voltage shall be
applied for one minute. Refer to Section 7.1.3 before performing test.
- *Perform insulation-resistance tests on control wiring with respect to ground. The applied
potential shall be 500 volts dc for 300-volt rated cable and 1000 volts dc for 600-volt rated
cable. Test duration shall be one minute. For units with solid-state components or control
devices that cannot tolerate the applied voltage, follow manufacturer’s recommendation.
- Perform electrical tests on instrument transformers in accordance with Section 7.10.
- Perform ground-resistance tests in accordance with Section 7.13.
- Test metering devices in accordance with Section 7.11.
- Control Power Transformers
- Perform insulation-resistance tests. Perform measurements from winding-to-winding
and each winding-to-ground. Test voltages shall be in accordance with
manufacturer’s published data. In the absence of manufacturer’s published data, use
Table 100.1.
- Verify correct function of control transfer relays located in switchgear with multiple
power sources.
- Verify operation of switchgear/switchboard heaters and their controller.
- Perform electrical tests of surge arresters in accordance with Section 7.19.
- *Perform online partial-discharge survey in accordance with Section 11.
- Perform system function tests in accordance with Section 8.
C. Test Values – Visual and
Mechanical
- Compare bolted connection resistance values to values of similar connections. Investigate
values which deviate from those of similar bolted connections by more than 50 percent of the
lowest value. (7.1.A.8.1)
- Bolt-torque levels shall be in accordance with manufacturer’s published data. In the absence
of manufacturer’s published data, use Table 100.12. (7.1.A.8.2)
- Results of the thermographic survey shall be in accordance with Section 9. (7.1.A.3)
D. Test Values – Electrical
- Compare bolted connection resistance values to values of similar connections. Investigate
values which deviate from those of similar bolted connections by more than 50 percent of the
lowest value.
- Insulation-resistance values of bus insulation shall be in accordance with manufacturer’s
published data. In the absence of manufacturer’s published data, use Table 100.1. Values of
insulation resistance less than this table or manufacturer’s recommendations should be
investigated. Dielectric withstand voltage tests shall not proceed until insulation-resistance
levels are raised above minimum values.
- If no evidence of distress or insulation failure is observed by the end of the total time of
voltage application during the dielectric withstand test, the test specimen is considered to
have passed the test.
- Minimum insulation-resistance values of control wiring shall not be less than two megohms.
- Results of electrical tests on instrument transformers shall be in accordance with Section 7.10.
- Results of ground-resistance tests shall be in accordance with Section 7.13.
- Accuracy of metering devices shall be in accordance with Section 7.11.
- Control Power Transformers
- Insulation-resistance values of control power transformers shall be in accordance with
manufacturer’s published data. In the absence of manufacturer’s published data, use
Table 100.1. Values of insulation resistance less than this table or manufacturer’s
recommendations should be investigated.
- Control transfer relays should perform as designed.
- Heaters should be operational.
- Results of electrical tests on surge arresters shall be in accordance with Section 7.19.
- Results of online partial-discharge survey should be in accordance with manufacturer’s
published data. In the absence of manufacturer’s published data, refer to Table 100.23.
- Results of system function tests shall be in accordance with Section 8.
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