CONSOLIDATED EDISON CO. OF NEW YORK, INC.
4 IRVING PLACE
NEW YORK, NY 10003
DISTRIBUTION ENGINEERING DEPARTMENT
SYSTEM DESIGN SECTION
SPECIFICATION EO – 4019
REVISION 34
DECEMBER 2015
EFFECTIVE DATE
DECEMBER 28, 2015
TESTING OF AC FEEDERS
OPERATING AT
4kV TO 33kV
FILE: SYSTEM OPERATION MANUAL No. 5
FIELD MANUAL No. 6, Section No. 8
TARGET AUDIENCE
REGIONAL ENGINEERING, SUBSTATION
OPERATIONS, SYSTEM OPERATION,
FIELD OPERATION AND DISTRIBUTION
ENGINEERING
NESC REFERENCE
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Page 1/13
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TABLE OF CONTENTS
PARAGRAPH
DESCRIPTION
1.0
SCOPE
2.0
APPLICATION
3.0
GENERAL
4.0
DEFINITIONS
5.0
HIPOT TESTING 13kV, 27kV OR 33kV
DISTRIBUTION FEEDERS
TABLE I
VOLTAGE AND LEAKAGE CURRENT LIMITS FOR
HIPOT TESTS
TABLE II
VOLTAGE AND LEAKAGE CURRENT LIMITS FOR
REDUCED VOLTAGE HIPOT TESTS
TABLE III
VOLTAGE AND LEAKAGE CURRENT LIMITS FOR
RAISED VOLTAGE HIPOT TESTS
6.0
AMMETER CLEAR TEST
7.0
EQUIPMENT TO BE DISCONNECTED PRIOR TO
TESTS
8.0
VALIDATION OF TESTING MEASUREMENTS
9.0
REFERENCES
ATTACHMENTS
TABLE IV
AMMETER CLEAR TEST LIMITS
APPENDIX A
FEEDER LIST
APPENDIX B
NOTES TO TABLE I, TABLE II, AND TABLE III
Specification
Revision
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Date
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System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
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TESTING OF AC FEEDERS
OPERATING AT 4 kV TO 33 kV
1.0
SCOPE
This document specifies the electrical tests performed on 4, 13, 27, and 33 kV AC
feeders to verify the restoration of adequate electrical insulation levels and the
absence of short-circuit conditions following an outage. These tests are described
as a High Potential Test (Hipot) and an Ammeter Clear Test.
2.0
APPLICATION
This specification applies to all Regions.
3.0
GENERAL
The application of this specification shall be in accordance with the “General
Instructions Governing Work on System Electric Equipment,” and under the
jurisdiction of the District Operator.
3.1
The Regional Engineering Manager, Control Center Shift Manager,
District Operator, or the System Design Department Manager of
Distribution Engineering may waive Hipot Test requirements based on
system conditions. These conditions include: network feeder
contingencies, local second or third conflicts, next contingency resulting
in overloads or customer outages, customers out of service, extreme
weather, or there is no indication of an additional fault on the feeder. The
criteria used to waive the Hipot Test must be entered in the Electric
Control Center Shift Manager’s log book and communicated (e.g. emailed) to the System Design Department Manager of Distribution
Engineering in a timely manner.
3.2
A VLF Hipot Test is the preferred High Potential Test and should be used
whenever a test set is available.
3.3
Hipot Tests on 4kV feeders are not required by Distribution Engineering.
Specification
Revision
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System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
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4.0
5.0
DEFINITIONS
4.1
VLF Hipot Test – A High-Potential withstand test using a very low
frequency (VLF) power source. The typical VLF frequency is 0.1 hertz. A
VLF Hipot test is the preferred method of High-Potential testing and
should be used whenever a VLF test set is available.
4.2
DC Hipot Test – A High-Potential withstand test using a DC power
source. A DC Hipot test should be used only when a VLF test set is not
available.
4.3
Ammeter Clear Test – A low-voltage test using a 60 Hz 125V AC power
source to verify the absence of short circuits on or between the primary
feeder conductors or grounds on transformer secondaries.
4.4
Feeder Crossing – The portion of a feeder that runs along a bridge or
under a waterway.
4.5
Network Reliability Index (NRI) – A statistical value indicating a
networks susceptibility to a shutdown. Refer to EO-2152 and EOP-5022
for more information.
4.6
Forced Outage – Any outage where the feeder was automatically
removed from service or unable to be restored to service due to a fault.
This includes Open-Auto (AUTO), Fail-on-Test (FOT), and Cut-In-OpenAuto (CIOA) due to a fault.
4.7
Planned Outage – Any outage where the feeder was deliberately taken
out of service. This includes Scheduled (SCHD), When Ready (WR),
Isolated (ISO), Rapid Availability (RAP), or Off-On-Emergency (OOE1
or OOE2) outages.
HIPOT TESTING 13kV, 27kV OR 33kV DISTRIBUTION FEEDERS
5.1
Subject feeders to a Table I Hipot Test for five (5) minutes following:
5.1.1
Any forced outage.
5.1.2
Any outage where station work was performed that disturbed
feeder clearances.
Specification
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1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
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5.1.3
Any outage where a portion of the feeder has been out of service
longer than six (6) months. (The Hipot Test is only required on the
portion of the feeder being picked-up).
5.1.4
Any outage where a total of four (4) or more sections of feeder
cable are installed or replaced.
5.1.5
A high tension customer installation or repair on new or existing
equipment or cable.
NOTE: High tension equipment or cable which is directly
connected to the Company’s supply feeder or is energized by
closing the line circuit breaker or circuit closing device must have
been subjected to a Hipot Test within the six (6) months prior to
energization.
5.1.6
A planned outage to break down a self-clearing (e.g. sub-cycle)
fault.
NOTE: The duration of the Hipot Test will be increased to thirty (30)
minutes if any condition in the following section (5.2) is met. This
increase in duration does not apply during the summer period, June 1
through August 31, or when dictated by system conditions.
5.2
Subject a feeder to a Table I Hipot Test for thirty (30) minutes following
a non-summer outage if the feeder meets the criteria in Appendix A.
These feeders have not received a 30 minute Hipot test during the previous
three (3) years and operate in networks with a NRI greater than 0.2.
Refer to Appendix B for notes.
Specification
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Date
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System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
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5.3
Exceptions to the Hipot Test:
5.3.1 Feeders that contain a grounding transformer or have no source of
backfeed (from network transformers or unit substations) will only
be subjected to a Table II Reduced Voltage Hipot Test for five (5)
minutes.
Refer to Appendix B for notes.
5.3.2
Subject feeders to a Table III Raised Voltage Hipot Test for thirty
(30) minutes when a “condition” is not able to be established after:
5.3.2.1 A forced outage. This only applies when there is a
confirmed fault on the feeder.
5.3.2.2 The feeder was proactively taken out of service to locate a
self-clearing fault (as in section 5.1.6).
Refer to Appendix B for notes.
Specification
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Date
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System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
Paper copies of procedures and instructions are uncontrolled and therefore may be outdated. Please consult Distribution
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Page
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5.3.3
Any forced outages due to a non-fault condition, such as an
overtrip due to mis-co-ordination with a downstream device (e.g.
Loop FVRS) or a CIOA due to a breaker problem or inrush, are not
required to be Hipot Tested. (Refer to the Power Quality
SharePoint site for more information on inrush versus fault
characteristics).
5.3.4
Feeders that contain crossings only require a Table II Reduced
Voltage Hipot Test for five (5) minutes following a forced outage.
Hipot Testing that follows a Planned Outage may be waived for
feeders with crossings even if that feeder appears in Appendix A.
5.3.5
The testing of feeders with Metro North open-wire portions is
covered by SO 18-07.
NOTE: When a Hipot Test is required after a forced outage it will be
applied to all portions of the feeder; including those partially restored by
the use of sectionalizing switches.
6.0
AMMETER CLEAR TEST
All AC distribution feeders should be subjected to an Ammeter Clear Test before
they are restored to service. Where the feeder is also subjected to a Hipot Test, the
Ammeter Clear Test should be performed prior to the Hipot Test. The results of
the Ammeter Clear Test shall conform to the requirements stated in Table IV.
Refer to SO 11-06 for information on waiving the Ammeter Clear Test.
7.0
EQUIPMENT TO BE DISCONNECTED PRIOR TO TESTS
The following apparatus shall be disconnected prior to performing a Phase-toGround DC or VLF Hipot Test on any distribution feeder:
• Phase to neutral connected potential transformers
• Lightning arrestors
• Grounding transformers
• Shunt reactors
• Any transformer with a neutral/ground connected HV winding
• High tension customer equipment
NOTE: Lightning arrestors are not required to be disconnected during Reduced
Voltage Hipot Test.
Specification
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Date
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System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
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8.0
VALIDATION OF TESTING MEASUREMENTS
8.1
Prior to the application of any Hipot Test, test facilities leakage
measurements shall be made at Hipot Test voltage for five minutes.
8.2
Upon the completion of any Hipot Test, test facilities leakage
measurements shall be made at Hipot Test voltage for five minutes.
8.3
At stations with ammeter test sets, the condition of the test set shall be
checked for ground continuity before and after each test.
Specification
Revision
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Date
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System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
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9.0
REFERENCES
SPEC. NO.
TITLE
FILED IN
ES-1002
Specification of Proof Testing
of Station Electric Equipment
and Circuits
Station Electric Section
Manual
EO-2022
General Specification for High
Tension Service
Application & Design
Manual No. 4
EO-2152
Distributed Network Reliability
Improvements
Application & Design
Manual No. 4
EO-4035
Operating and Maintenance of
Equipment on High Tension
Customer’s Premises
System Operation
Manual No. 5
EOP-5022
Automated Voltage Reduction
Program and Demand Response
Programs
Electric Operations
Guidelines: Manual
No. 4
SO11-06-11
Guide for Waiving Ammeter
Clear Test
Public Folders\Con Ed Co of
NY\Central Operations\STO System & Transmission
Operations\System Operation
Procedures
SO18-07-15
Operating Requirements
Associated with Distribution
Feeders Supplying Metro North
Public Folders\Con Ed Co of
NY\Central Operations\STO System & Transmission
Operations\System Operation
Procedures
CIOA Guideline
http://pq/CIOA/VisioCIOA%20guideline.pdf
Christopher G. Jones (Signature on File)
Department Manager, System Design
Distribution Engineering Department
George Murray (Signature on File)
Section Manager, Dist. Cable Systems
Distribution Engineering Department
John Foglio
REVISION 34:
Changed requirements for Hipot Testing.
Changes made to add clarity.
Specification
Revision
EO-4019
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Filing Information
Rev Date
FILE:
SYSTEM OPERATION MANUAL No. 5
FIELD MANUAL No. 6, Section No. 8
Effective
Date
12/28/2015
System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
Paper copies of procedures and instructions are uncontrolled and therefore may be outdated. Please consult Distribution
Engineering Intranet Site Distribution Engineering or http://distribution, for the current version prior to use.
Page
9/13
TABLE IV
AMMETER CLEAR TEST LIMITS
Maximum Limits
1.
If the ammeter reading obtained during an Ammeter Clear Test is in excess of
the following values, the feeder shall not be placed in service until the cause of
the high reading has been determined and, if necessary, eliminated:
NOMINAL OPERATING
VOLTAGE BETWEEN
CONDUCTORS
________[KV]_________
NORMAL MAXIMUM
ALLOWABLE AMMETER
CLEAR TEST READING
______ [AMPERES]______
33
0.3
27
0.4
13
0.1
NOTE: Current readings in excess of those specified may be accepted if
equally consistent on all phases with results of previous AC tests
on the feeder.
Interpretation of Reading
2.
The following tabulation shall be used as a guide to interpret readings of the
Ammeter Clear Tests:
APPROXIMATE AMMETER
CONDITION OF FEEDER
__ READING [AMPERES]__
Feeder grounded
3-5
Phase to phase short circuit
3-5
Short Circuit on low
voltage side of substation
transformer or large high
tension customer transformer
2-3
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TABLE IV (Cont’d)
APPROXIMATE AMMETER
__ READING [AMPERES]__
CONDITION OF FEEDER
Short circuits on low voltage
side of distribution transformer:
a.
33kV System
0.9*
b.
27kV System
1.4*
c.
13kV System
4.0*
d.
4kV System
2.0**
27kV shunt reactor, neutral
ground switch closed.
0.1
(per shunt reactor)
13kV grounding transformer
neutral ground switch closed
2.25
(per grounding transformer)
Excitation current of transformer
and charging current of cable.
Less than 0.1
* Per 1000 kVA of transformer capacity.
** Per 10 kVA of transformer capacity.
3.
If any of the following types of transformers are connected to the feeder when the
Ammeter Clear Test is made, an abnormally high reading will be obtained:
a.
Three-phase transformer or auto-transformer banks with a three-legged core
with the feeder winding wye-connected and the neutral grounded.
b.
Wye-delta transformer banks with the neutral grounded, where the wye
winding is connected to the portion of the feeder on which the Ammeter Clear
Test is being made.
Specification
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Manual No. 5
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APPENDIX A
FMS Online will now provide a real time list of feeders that meet the Appendix A criteria. These
are feeders that have not received a 30 minute Hipot test during the previous three (3)
years and operate in networks with a NRI greater than 0.2. For a list of these feeders:
•
•
•
Open FMS Online.
Select ‘Reports.’ A drop-down list will appear.
Select ‘Appendix A Feeders.’ A current list of all the feeders that meet the Appendix A
criteria will appear.
Note 1
This list is compiled in real-time by FMS Online.
Note 2
The Control Center Shift Manager may waive a Hipot Test on any
feeder on this list if it can be verified that a 30 minute Hipot was carried
out during the previous three (3) calendar years, this is a non-network
feeder, or the feeder has a grounding transformer.
Note 3
For feeders with crossings, a Hipot Test following a Planned Outage
may be waived even if that feeder appears on Appendix A.
•
•
•
To request access to FMS Online:
Access the Product Access System via http://sto/Information/Request.aspx.
Select ‘New Access Request.’
Check ‘Feeder Management System (FMS); select Read Only in the ‘Type of Access’
field. After you acknowledge the requirements you can submit your request.
Specification
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APPENDIX B – NOTES TO TABLE I, TABLE II, AND TABLE III
Note A The VLF Hipot Test is preferred and should be used whenever the
test set is available.
The rate of rise of the applied voltage should not exceed 1kV per
second with a pause of two or three seconds (not to exceed 5
seconds) after every 5kV step.
Note B Hipot Tests are satisfactory only if the leakage current is constant or
decreases without fluctuations or surges after the full test potential
has been applied and is below the specified values at the end of the
test. Current readings in excess of those specified may be accepted
if they are consistent with the results of previous tests on the feeder.
For the rate of rise of applied voltage, refer to Note A.
Note C Upon the completion of tests on each phase and with the test set still
connected to the cable, the supply voltage to the test set shall be
reduced to zero and the cable grounded.
Note D High tension customer's incoming devices shall be opened
prior to performing a Hipot Test. All high tension customer's
equipment connected to the line side of the incoming
disconnect device shall be subject to the Company Hipot
values in force during the time of the test.
Note E All Hipot Tests are to be made with all conductors connected
together and ground.
On 33kV cable, Hipot Tests on 3-conductor cable or where 3
single conductor cables are in 1 duct, test between all 3
conductors connected together and ground. On single
conductor cable in separate ducts, test between phase and
ground with the other phases grounded.
Specification
Revision
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Rev Date
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Date
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System Operations
Copyright Information
1966-2015 Consolidated Edison Co. of New York, Inc.
Manual No. 5
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