Download summary of requirements

August 17, 2009
SUMMARY OF REQUIREMENTS
The following is a brief summary of the revised paragraphs in the Standard for Standard For
Safety For Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear, UL 1558, which have
a future Effective Date of January 9, 2013 and the action that may be required to determine
compliance.
Paragraphs
General Subject and Comment
4.1
Construction and test requirements for switchgear shall be in accordance
with ANSI C37.20.1 and ANSI C37.51. Deletion of the dated references
to each standard requires switchgear to be investigated using the 2002
version of C37.20.1 rather than the 1993 version, and the 2003 version
of C37.51 rather than the 1989 edition. Where the construction and test
requirements in the new editions is different than the previous editions, it
will be necessary to review construction and test reports to determine if
the switchgear meets the requirements in the newer version, and
retesting may be required.
All paragraphs that
reference to C37.20.1
See attached for summary of changes to C37.20.1 which will possibly
impact currently listed products.
All paragraphs that
reference C37.51
See attached for summary of changes to C37.51 which will possibly
impact currently listed products.
Subject:
Page 2 of 12
«ACTIONDATE»
Comparison: C37.20.1-1993 vs -2002
Clause in C37.20.11993
Clause in C37.20.12002
1.1 Scope
1.2 References
1 Scope
2 References
2 Definitions
3 Service Conditions
4 Ratings
4.1 General
4.2 Voltage and Insulation
Levels
3 Definitions
4 Service Conditions
5 Ratings
5.1 General
5.2 Voltage and Insulation
Levels
4.3 Rated Frequency
4.4.1 Rated Continuous
Current
4.4.2 Continuous Current
ratings
5.3 Rated power frequency
5.4.1 Rated Continuous current
4.4.3 Rated Short-Time
Current
5.4.3 Rated Short-Time
withstand current
4.4.4 Rated Short-Circuit
Current
5.4.4 Rated Short-Circuit
Withstand Current
4.5 Temperature Limitations
4.6 Current Transformer
Ratings
4.7 Current Transformer
Accuracies
--
5.5 Temperature Limitations
5.6 Current Transformer
Ratings
5.7 Phase Current transformer
accuracies
5.8 Shunts for use in LV dc
switchgear
5.4.2 Continuous current
ratings
Differences / Effect
Essentially the same
Editions of referenced
standards have been updated
Essentially the same
Essentially the same
Essentially the same
Addition of preferred rating of
1000 v dc. Does not affect
existing certifications
Essentially the same
Essentially the same
Some revisions in preferred
current ratings. Does not
affect existing certifications
Clarified differences between
ac and dc ratings. Does not
affect existing certifications.
Clarified requirements for dc
gear. Added explanatory
notes. Does not affect existing
cerfications
Essentially the same
Added requirements for
thermal ratings per C57.13
Essentially the same
Shunts to comply with IEEE
std 316. May require review
for Currently Certified DC
switchgear
Subject:
Page 3 of 12
5 Tests
5.1 General
5.2 Design Tests
--
6 Tests
6.1 General
6.2 Design Tests
6.2.1 Test Arrangements
5.2.1 Dielectric Tests
5.2.2 Rated Continuous
current tests
5.2.2.1 Test area conditions
6.2.2 Dielectric Tests
6.2.3 Rated continuous current
tests
6.2.3.1 Test area conditions
5.2.2.2 Ambient air
temperature limits
5.2.2.3 Measurement of
ambient air temperature
5.2.2.4 Method of measuring
temperature
5.2.2.5 Duration of Tests
5.2.2.6 Frequency of test
current
--
6.2.2.2 Ambient air temperature
limits
6.2.3.3 Measurement of
ambient air temperature
6.2.3.4 Method of measuring
temperature
6.2.3.5 Duration of Tests
6.2.3.6 Frequency of test
current
6.2.3.7 Value of Test Current
5.2.2.7 Copper conductors
for use in continuous current
tests
6.2.3.8 Copper conductors for
use in continuous current tests
5.2.3 Short-time current
withstand tests
6.2.4 Short-time current
withstand tests
«ACTIONDATE»
Essentially the same
Added this section to define
appropriate test arrangements.
Reflects current practice.
Does not affect currently
certified products.
Essentially the same
Essentially the same
Now requires measuring the
air velocity in test area.
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Now requires testing AC gear
with three phase source
Added bus and conductor
sizes for 5000 A ratings. May
need to verify existing products
comply.
Greatly increased description
of test methods and setup,
including testing of neutral and
ground bus. Further clarified
differences between ac and dc
gear. May need to verify
existing products comply.
Subject:
5.2.4 Short-Circuit current
withstand tests
Page 4 of 12
6.2.5 Short-Circuit current
withstand tests
«ACTIONDATE»
Expanded performance
criteria.
6.2.5.2 added requirements for
test on LV dc switchgear
5.2.5 Mechanical Endurance
Tests
6.2.6 Mechanical Endurance
Tests
5.2.6 Flame-Resistance
Tests
5.2.7 Rod Entry Test
5.2.8 Paint Qualification
Tests
5.2.9 Rain Test
--
6.2.7 Flame-Resistance Tests
5.3 Production Tests
6.3 Production Tests
5.4 Conformance Tests
5.5 Field Dielectric Tests
6.4 Conformance Tests
6.5 Field Dielectric Tests
6.2.8 Rod Entry Test
6.2.9 Coating (Paint)
Qualification Tests
6.2.10 Rain Test
6.2.11 Gaskets Used in
Outdoor Switchgear
6.2.5.4 Added requirements for
equipment primary disconnect
device short circuit current
withstand testing
GREATLY increased the
number of operations.
Expanded description of test
method and performance
requirements.
Essentially the same
Essentially the same
Test method is now per ASTM
D1654-1992 (was –79a)
Essentially the same
Added test requirements. May
require review of current
certifications
Very similar. Additional
requirements for dc gear.
Still refers to C37.51-1989
Essentially the same.
Subject:
Page 5 of 12
6 Construction
6.1.1 Buses and Primary
Connections
7 Construction
7.1.1 Buses and Primary
Connections
6.1.2 Grounding
7.1.2 Grounding
6.1.3.1 Wiring
7.1.3.1 Wiring
6.1.3.2 Secondary Wiring
Terminals
6.1.3.3 Terminal Blocks
6.1.3.4 Designation of
auxiliary switches and
contacts
6.1.3.5 Device Function
Numbers
7.1.3.2 Secondary Wiring
Terminals
7.1.3.3 Terminal Blocks
7.1.3.4 Designation of auxiliary
switches and contacts
6.1.3.6 Voltage limits of
instrument and control
circuits
6.1.3.7 Polarity of dc
connections to device coils
6.1.3.8 Voltage circuit
protection
7.1.3.7 Voltage limits of
instrument and control circuits
6.1.3.8.1 Control Power
Transformers
7.1.3.8.1 Control Power
Transformers
6.1.3.8.2 Voltage
transformers
6.1.3.8.3 Isolation
6.1.3.9 Current transformer
secondary circuit protection
7.1.3.8.2 Voltage transformers
6.1.4 Miscellaneous
6.1.4.1 Nameplate marking
7.1.4 Miscellaneous
7.1.4.1 Nameplate marking
6.1.4.2 Wiring Devices
6.1.4.3 Ventilation openings
and vent outlets
6.1.4.4 Service
disconnecting means
7.1.4.2 Wiring Devices
7.1.4.3 Ventilation openings
and vent outlets
7.1.4.4 Service disconnecting
means
6.2 Materials and Finish
6.2.1 Materials
7.2 Materials and Finish
7.2.1 Materials
7.1.3.5 Device Function
Numbers
7.1.3.6 Polarity of dc
connections to device coils
7.1.3.8 Voltage circuit
protection
7.1.3.8.3 Isolation
7.1.3.9 Current transformer
secondary circuit protection
«ACTIONDATE»
Essentially the same.
Reference to CC-1 updated
from 1984 to 1993.
Requirements for AC and DC
switchgear are now separated.
Door is now required to be
bonded with 14 AWG minimum
conductor
Significant relaxations in
requirements. Does not affect
currently Listed gear.
Same
Essentially the same
Essentially the same
Essentially the same.
Reference to C37.2 updated
from 1991 to 1996.
Essentially the same
Essentially the same
Added items c and d, requiring
overcurrent protection in
accordance with NFPA 70 and
separation of wiring to bus.
Required transformer
protection has changed for
some ratings. Requires review
of cpt protection.
Essentially the same
Essentially the same
Added requirement to consider
open circuit protection when
wiring connects external to
gear.
Must now mark main bus
current rating, date of
manufacture and instruction
manual number
Essentially the same
Essentially the same
Essentially the same. Updated
NFPA 70 reference from 1993
to 2002.
Essentially the same
Subject:
Page 6 of 12
6.2.2 Finishes and Color
7.2.2 Finishes and color
--
7.2.3 Insulating materials for
support of primary conductors
6.3 Barriers
6.4 Buses and Connections
6.5 Access doors and covers
6.6 Closing and Tripping
6.7 Indoor LV Switchgear
6.8 Outdoor LV Switchgear
6.9 Pull box
6.10 Arrangements with
stationary circuit breakers
6.11 Arrangements with
drawout circuit breakers
6.11.1 Interlocks
6.11.2 Circuit breaker
retention and locking
6.11.3 Fuse accessibility
7.3 Barriers
7.4 Buses and Connections
7.5 Access doors and covers
7.6 Closing and Tripping
7.7 Indoor LV Switchgear
7.8 Outdoor LV Switchgear
7.9 Pull box
7.10 Arrangements with
stationary circuit breakers
7.11 Arrangements with
drawout circuit breakers
7.11.1 Interlocks
7.11.2 Circuit breaker retention
and locking
7.11.3 Fuse accessibility
«ACTIONDATE»
Changed ASTM reference
from 1989 to 1997. Added
note 3 regarding UV resistant
coatings. Since this is a note,
it is not normative.
Shall withstand dielectric tests
and flame resistance tests.
Reflects current practice.
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Essentially the same
Subject:
Page 7 of 12
6.11.4 Removable element
interchangeability
7.11.4 Removable element
interchangeability
6.11.5 Fuses on separate
removable elements
7.11.5 Fuses on separate
removable elements
6.11.6 Secondary
Disconnect devices
6.12 Primary Cable space
6.13 Precautionary labels
7.11.6 Secondary Disconnect
devices
7.12 Primary Cable space
7.13 Precautionary labels
6.14 Lifting devices
7 Application Guide for LV
Switchgear
7.1 Unusual Service
conditions
7.14 Lifting devices
8 Application Guide for LV
Switchgear
8.1 Unusual Service Conditions
7.2 System Characteristics –
voltage and frequency
7.3 Overvoltage
considerations – Insulation
levels
8.2 System Characteristics –
voltage and frequency
8.3 Overvoltage considerations
– Insulation levels
7.4 Continuous Current
rating and overload capacity
7.5 Short circuit
considerations
7.6 Nuclear power plant
application
7.7 Associated devices used
in LV switchgear
7.7.1 Current transformers
8.4 Continuous Current rating
and overload capacity
8.5 Short Circuit considerations
7.7.2 Surge Protective
devices
7.7.3 Ground detectors
--
8.7.2 Surge Protective devices
--
8.7.5 LV dc switchgear
enclosure ground/live relays
(e.g., for transit applications)
8.8 Protection and isolation of
switchgear connected to other
circuit protective equipment
7.8 Protection and isolation
of switchgear connected to
other circuit protective
equipment
7.9 Overcurrent Protection
8.6 Nuclear power plant
application
8.7 Associated devices used in
LV switchgear
8.7.1 Current Transformers
8.7.3 Ground detectors
8.7.4 LV dc shunts and dc
current transformers
8.9 Overcurrent protection
«ACTIONDATE»
Added requirement to reject
elements of different current
ratings.
Eliminated use of switches in
series with fuses. May require
review
Essentially the same
Essentially the same
Essentially the same.
Reference to Z535.4 updated
from 1991 to 1998
Essentially the same
Essentially the same, except
7.1.4.6. Seismic requirements
changed from IEEE 344-1987
to C37.81-1989. Since
Seismic investigation has not
been part of Listing, this does
not affect currently Listed
products.
Essentially the same
Essentially the same. Added
reference to application
information for surge arrestor &
capacitors
Essentially the same. Added
some higher current ratings
Essentially the same
Essentially the same
Essentially the same.
Additional selection guidance
added
Essentially the same
Essentially the same
Additional requirements for
shunts. Possible review
needed for DC switchgear
Additional requirements.
Possible review needed for DC
switchgear
Essentially the same
Eliminated allowance for tow-
Subject:
8 Guide for handling,
storage, and installation
Page 8 of 12
9. Guide for handling, storage,
and installation
«ACTIONDATE»
phase overcurrent, residual
ground arrangement. Reflects
current practice.
Not reviewed as this is not
considered part of Listing
investigations.
Subject:
Page 9 of 12
«ACTIONDATE»
Comparison: C37.51-1989(R1995) vs C37.51-2003
Clause in C37.511989(R1995)
1 Scope
2 Referenced Standards
Clause in C37.51-2003
1 Scope
1.1 Control and Instrumentation
1.2 Installations not covered
1.3 Purpose
2 Referenced Standards
-Section 3
General Test Conditions
3.1 Ambient Conditions
3.2 Protection and Conditions
3.2.1 General
3.2.2 Control Power
Transformers
3 Definitions
Section 4
General Test Conditions
4.1 Ambient Conditions
4.2 Protection Requirements
4.2.1 General
4.2.2 Control Power Transformers
3.2.3 Voltage Transformers
Section 4 Conformance Test
Requirements
4.1 General
4.2 Test Requirements
4.3 Test Arrangements
4.2.3 Voltage transformers
Section 5 Conformance Test
Requirements
5.1 General
5.2 Test Requirements
5.3 Test Arrangements
4.4 AC Dielectric Withstand
Tests
5.4 Dielectric Tests
Differences /
Effect
No significant differences
The following standards
have newer editions
C37.16, C37.09, C37.13,
C37.20.1, C37.26, IEEE
No. 4
Definitions were added
Essentially the same
Essentially the same
Some of the ratings of
some short circuit
protection required by
Table 1 have changed
Essentially the same
Essentially the same
Essentially the same
Added 5000 A ratings
Added guidance on
determining representative
test samples
Added allowance to
disconnect transformers
during the test
Subject:
Page 10 of 12
4.5 Mechanical Performance
Tests – Removable CBs
4.5.1 Test Procedure
4.5.2 Cycles of Operation
5.8 Mechanical Performance
Tests – Removable CBs
5.8.1 Test Procedure
5.8.2 Cycles of Operation
4.5.3 Performance
5.8.3 Performance
4.6 Continuous Current Test
5.5 Continuous Current Test
4.6.1 Duration of Tests
4.6.2 Measurement of Ambient
Air Temperature
4.6.3 Method of Measuring
Temperature
4.6.4 Copper Conductors for
Use in Continuous Current
Tests
4.6.5 Performance
5.5.1 Duration of Tests
5.5.2 Measurement of Ambient Air
Temperature
5.5.3 Method of Measuring
Temperature
5.5.4 4.6.4 Copper Conductors for
Use in Continuous Current Tests
5.5.5 Performance
«ACTIONDATE»
Essentially the same
Added a seventh step to
check mechanism
discharge or blocking after
each of the 10 operations
Clarified the acceptance
criteria to reflect steps
taken to ensure the device
is in “essentially the same
condition”
Each phase must now
carry no less than rated
current (previously require
average of three phases to
be no less than rated
current)
Essentially the same
Essentially the same
Essentially the same
Added required
conductors for 5000 A
ratings
Essentially the same
Subject:
4.7 Short-Time Current
Withstand Test
4.7.1 Test Circuit Conditions
4.7.2 Short-Time Current Duty
Cycle
4.7.3 Performance
Page 11 of 12
«ACTIONDATE»
5.6 Short-Time Current Withstand
Test and subclauses 5.6.1.1, .2,
and .3
5.6.2.1 Prospective current
determination
5.6.2.2 Power factor
determination
5.6.2.3 Test Voltage and
Frequency
5.6.2.6 Test Current
5.6.2.5 Test Duration
Single phase testing now
permitted.
5.6.2.7 Performance
Clarified the acceptance
criteria to reflect steps
taken to ensure the device
“shows no physical
damage”
Added requirements to
perform short time tests on
neutral bus (if provided).
Note this may cover the
short circuit withstand
tests conducted on neutral
bus if the short-time and
short circuit ratings are
equal (see 5.7.1.1)
Added requirements to
perform short time tests on
ground bus. Note this may
cover the short circuit
withstand tests conducted
on neutral bus if the shorttime and short circuit
ratings are equal (see
5.7.1.1).
--
5.6.3 Neutral Bus and
Connections
--
5.6.4 Ground Bus and
Connections
Esssentially the same
Essentially the same
Subject:
4.8 Short-Circuit Current
Withstand Tests
Page 12 of 12
5.7 Short-Circuit Current
Withstand Tests
5.7.1.2 Test possibly required at
multiple voltage levels
5.7.1.3 Circuit Breaker
Compartment involved
«ACTIONDATE»
Testing must be done at
maximum voltage and also
at maximum short circuit
current. Previous version
did not require testing at
600 V.
5.7.1.1 Short-time withstand
current test may cover shortcircuit withstand current test
Covering short circuit
current withstand test with
short-time may have been
practiced previously,
although original wording
may not have been
correct.
4.8.1 Test Duration
4.8.2 Test Circuit conditions
5.7.3 Neutral bus (if applicable),
ground bus, and connections
5.7.2.3 Test duration
5.7.2.1 Circuit characteristics
Essentially the same
Essentially the same
4.8.3 Performance
5.7.2.4 Test current
5.7.2.5 Performance
5.7.2.2 Test Connections
5 Treatment of Failures
6 Accessory Devices
7 Production Tests
7.1 AC Dielectric Withstand
Tests
7.2 Mechanical Operation
Tests
7.3 Grounding of Instrument
Transformer Cases Test
7.4 Electrical Operation and
Wiring Tests
8 Retesting
6 Treatment of Nonconforming
results
-7 Production Tests
7.1 General
7.2 Dielectric Withstand Voltage
Tests
7.3 Mechanical Operation Tests
7.4 Grounding of Instrument
Transformer Cases Test
7.5 Electrical Operation and
Wiring Tests
8 Retesting
Clarified the acceptance
criteria to reflect steps
taken to ensure the device
“shows no physical
damage”
Essentially the same
Not in current draft
Essentially the same
Test may be a 1 second
test if the test voltage is
increased 10%
Essentially the same
Essentially the same
Essentially the same
Essentially the same