Industry Installation Guidelines for Pulse Width Modulated (PWM)
AC Drives
Industries discussed in this application technique include:
AutomotiveMarine and Offshore
Chemical/Specialty ChemicalMining and Steel
Food and BeverageTire Manufacturing
Forest Products/ConvertingWater/Waste Water
Summary of Changes
This manual has been extensively revised to reduce redundancies in previous version. There are different requirements in applications for
specific industries. The unique requirements of the Marine Industry are in Chapter 4 Marine and Offshore Industry. Other industries which
have more in common are discussed in Chapters 1…3 and Appendix B: Sample Requirements and Enclosure Specifications for Specific
Industry Types, which provides bulleted lists of the requirements for each of these industries. These industries include:
•Automotive
•Forest and pulp paper products
•Metal products
•Mining process products
•Oil and gas products
•Open pit mining products
This manual contains new and updated information as indicated in the following table.
Top icPa ge
Updated Safety Information link in Degree of Protection section of Chapter 1 and in the
Additional Resources table.
Added Control System Packaging for Corrosion Mitigation Design and Installation Guideline,
publication TIRE-RM001 and Control System Packaging for Corrosion Mitigation White Paper,
publication WWW-WP001 to Additional Resources table.
Moved General Precautions from Preface to Chapter 2.21
Consolidation of common information between industries into first three chapters rather
than spread across 10 chapters as in previous version
Moved Marine and Offshore Industry information from Chapter 7 in original document to
Chapter 4.
Creation of Sample Drive Installation Requirements Appendix to list standard drive
requirements.
Creation of Sample Requirements and Enclosure Specifications for S pecific Industry Types
Appendix to list unique requirements of cer tain industries.
10, 59
59
Var iou s
37
41
47
2Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
4Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
Preface
About This Publication
The purpose of this application technique is to provide basic information for different enclosure systems and environmental/location
considerations (to help protect against environmental contaminants), and power and grounding considerations needed to properly install a
Pulse Width Modulated (PWM) AC drive. The industry-specific guidelines in this document are meant to be used as examples - specific
locations are unique and the guideline examples should be adapted accordingly.
Pulse width modulation is a form of control used to generate a waveform necessary to operate an induction motor. With PWM control it is
possible to change the speed of the motor by varying the frequency sent to the motor. PWM drives are also known as Variable Frequency
Drives, and Adjustable Speed Drives.
Who Should Use This Manual
This manual is intended for qualified personnel who plan and design installations of PWM AC drives.
Recommended Agencies and Standards Publications
The following agencies and standards publications provide general information for installing drives and drive enclosures in regards to
environmental conditions and degrees of protection against ingress of contaminants.
National Electrical Manufacturers Association (NEMA)
1300 North 17th Street
Suite 1847
Rosslyn, VA 22209, USA
•No. 0 General Requirements - Canadian Electrical Code, Part II
•No. 0.4 Bonding and Grounding of Electrical Equipment (Protective Equipment)
•No. 14 Industrial Control Equipment for Use in Ordinary (Non- Hazardous) Locations
•No. 25 Enclosures for Use in Class 11 Groups E, F, and G Hazardous Locations
•No. 26 Construction and Test of Wireways, and Auxiliary Gutters, and Associated Fittings
•No. 40 Cutout, Junction, and Pull Boxes
•No. 76 Splitters
•No. 94 Special Purpose Enclosures
•No. 182.4 Plugs, Receptacles, and Connections for Communications Systems
National Fire Protection Association (NFPA)
Batterymarch Park
Quincy, MA 02169-7471, USA
www.nfpa.org
•NFPA 70 National Electrical Code
•NFPA 70e Standard for Electrical Safety Requirements for Employee Workplaces
•NFPA 79 Electrical Standard for Industrial Machinery
•NFPA 496 Purged and Pressurized Enclosures for Electrical Equipment
International Society of Automotive Engineers (SAE)
400 Commonwealth Drive
Warrendale, PA 15096-0001, USA
www.sae.org
•SAE HS 1738 SAE Standard - Electrical Equipment for Automotive Industrial Machinery
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
3 Park Avenue,
New York, NY 10016-5997, USA
www.ieee.org
•IEEE 45, Recommended Practice for Electrical Installations on Shipboard
6Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
American Bureau of Shipping (ABS)
ABS Plaza
16855 Northchase Drive
Houston, TX 77060, USA
www.eagle.org
•Rules for Building and Classing Steel Vessels 2009, Part 4, Vessel Systems and Machinery
The International Society of Automation (ISA)
67 Alexander Drive
Research Triangle Park, NC 27709, USA
www.isa.org
•ISA-71.04-2013, Environmental Conditions for Process Measurement and Control Systems: Airborne Contaminants
International Electrotechnical Commission (IEC)
Preface
3, rue de Varembé
P.O. Box 131
CH - 1211 Geneva 20 - Switzerland
www.iec.ch
•IEC Publication 529, contains descriptions and associated test requirements that define the degree of protection each IP numeral
specifies
•IEC Publication 60079, standard for installations in hazardous areas
•IEC Publication 60079-20, section for flammability group and temperature class of equipment installed in hazardous areas
•IEC Publication 60529, describes the complete test procedures for standard degrees of protection ratings
Conventions Used in This Manual
These conventions are used throughout this manual.
•Bulleted lists such as this one provide information, not procedural steps.
•Numbered lists provide sequential steps or hierarchical information.
Rockwell Automation Publication DRIVES-AT003C-EN-P - October 20207
Preface
Notes:
8Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
Chapter 1
Environmental Considerations
This chapter describes environmental considerations, standards, and agency requirements for enclosures for different environments. This
is not meant to be a comprehensive guide but provide information that can let you know the different regulations that need to be further
studied and complied with for your location. Please contact your local Rockwell Automation representative for assistance in selecting or
addressing environmental concerns.
General Information
You must evaluate the environment where your AC drive will be installed, identify any contaminants, and provide the correct degree of
protection for the AC drive and electronics in either a stand-alone installation or when mounting the drive inside an enclosure. This
evaluation and degree of protection helps to make sure the drive functions correctly and reliably. If the drive is going to be placed into an
environmental setting that is harsher than defined by the specified rating of the drive, it must be installed in the proper type of protective
enclosure. If the drive is not installed in the proper type of protective enclosure it can suffer failure from atmospheric contaminants which
produce corrosion.
Corrosion failures of industrial electronic equipment is a concern, especially in industry groups such as water/waste water, paper making,
steel, and tire manufacturing. For these industries, sulfur compounds that can attack electrical components and lead to failure are typical.
These failures can be unexpected because the relatively low levels of sulfur concentration that can lead to electronic failure are often not
perceived as severe by workers in those facilities. Electronic assemblies can fail due to several corrosion mechanisms. This corrosion can
occur with or without electrical voltage being present, and can also compromise insulated systems, if and when they become conductive.
Conformal coating of printed circuit boards can prevent some of the contamination challenges faced in the field; but, because all
components are not coated, there is still a need to review the applications and environments. Refer to Conformal Coating for Variable Speed
Drives, publication DRIVES-WP021
.
Enclosure Types and Ratings
What's in an Enclosure Rating?
As a way of standardizing enclosure performance, organizations like National Electrical Manufacturers Association (NEMA), Underwriters
Laboratories, Inc. (UL), Canadian Standards Association (CSA), International Electrotechnical Commission (IEC), and Association for Electrical,
Electronic and Information Technologies (Verband der Elektrotechnik, Elektronik und Informationstechnik [VDE]) use rating systems to
identify the ability of an enclosure to resist external environmental influences. Resistance to everything from dripping liquid, to hosedown, to
total submersion is defined by the rating systems. While all these rating systems are intended to provide information to help you make a
safer, more informed enclosure choice, there are notable differences between the rating systems.
North American Standards Organizations
In North America, NEMA, UL, and CSA are the commonly recognized standards organizations. Their ratings are based on similar application
descriptions and expected performance. UL and CSA both require enclosure testing by qualified evaluators in UL- and CSA-certified labs.
They also send site inspectors to verify that a manufacturer adheres to prescribed manufacturing methods and material specifications.
NEMA does not require independent testing and does not verify the compliance of the manufacturer.
Rockwell Automation Publication DRIVES-AT003C-EN-P - October 20209
Chapter 1 Environmental Considerations
North American enclosure rating systems also include a 4X rating that indicates corrosion resistance. This rating is based on the ability of
the enclosure to withstand prolonged exposure to saltwater spray. While a 4X rating is a good indicator that an enclosure can resist
corrosion, it does not provide information on how a specific corrosive agent will affect a given enclosure material. It is best to conduct a full
analysis of the specific application and environment to determine the best enclosure choice.
International Standards Organizations
Like NEMA, IEC does not require independent testing and does not verify the compliance of the manufacturer. Nevertheless, there are
differences in how enclosure performance is interpreted. For example, UL and CSA test requirements specify that an enclosure fails the
water-tight test if even a single drop of water enters the enclosure. In the IEC standards for each level of ingress protection (IP), a certain
amount of water is allowed to enter the enclosure.
IEC 60529 IP ratings do not specify construction requirements or degrees of protection against corrosive atmospheres, risk of explosion, or
conditions such as moisture or corrosive vapors. NEMA Type ratings do specify construction and performance requirements for most
environmental conditions. Because of this difference in construction requirements, and because the tests and evaluations for other
characteristics are not identical, the IEC enclosure classification designations cannot be exactly equated with NEMA enclosure Type
numbers.
Enclosure materials and construction must consider the following:
•Environmental considerations include moisture, temperature, solar affect, airborne particulate matter, and harsh or corrosive
chemicals present in the atmosphere.
•Safety issues including electrical code requirements, grounding needs, and others.
Choosing the incorrect solution can be costly and can adversely affect the performance of your installation.
Degree of Protection
IEC Publication 60529 describes standard Degrees of Protection that enclosures are designed to provide when properly installed.
Summary
The publication defines Degrees of Protection with respect to:
•Persons
•Equipment within the enclosure
•Ingress of water
It does not define:
•Protection against risk of explosion
•Environmental protection (for example: against humidity, corrosive atmospheres or fluids, fungus, or the ingress of vermin)
Note: The IEC test requirements for Degrees of Protection against liquid ingress refer only to water. The products on the Safety Products
page (https://ab.rockwellautomation.com/Safety
Nitrile seals. Nitrile seals have good resistance to a wide range of oils, coolants, and cutting fluids; however, some of the available lubricants,
hydraulic fluids, and solvents can cause severe deterioration of Nitrile and other polymers. Some of the products listed are available with
seals of Viton or other materials for improved resistance to such liquids. For specific advice on enclosure seals and protection against liquid
ingress, contact your local Rockwell Automation sales office.
) that have a high degree of protection against ingress of liquid include, in most cases,
10Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
Chapter 1 Environmental Considerations
IEC Enclosure Classification
The IEC enclosure classification for degree of protection is indicated by two letters and two numerals (IP_ _). International Standard IEC
60529 contains descriptions and associated test requirements that define the degree of protection that each numeral specifies. Table 1
indicates the general degree of protection indicated by the value and position of each numeral in the enclosure classification.
See the Abridged Descriptions of IEC Enclosure Test Requirements below for brief descriptions of the test requirements.
Note: For complete test requirements refer to IEC 60529.
Abridged Descriptions of IEC Enclosure Test Requirements
Refer to IEC 60529 for complete test specifications (for example: test apparatus configuration, tolerances, etc). For metric conversion
factors, see Safety Products page (https://ab.rockwellautomation.com/Safety
Tests for Protection Against Access to Hazardous Parts (first characteristic numeral)
).
The first characteristic numeral of the IP number indicates compliance with the following tests for the degree of protection against access
to hazardous parts. It also indicates compliance with tests shown in Tests for Protection Against Solid Foreign Objects (first characteristic
numeral) on page 12.
The protection against access to hazardous parts is satisfactory if adequate clearance is kept between the specified access probe and
hazardous parts. For voltage less than 1000V AC and 1500V DC, the access probe must not touch the hazardous live parts. For voltage
exceeding 1000V AC and 1500V DC, the equipment must be capable of withstanding specified dielectric tests with the access probe in the
most unfavorable position.
Table 1 - Numeric Conventions for Protection Against Access to Hazardous Parts
First Numeral
Protection of persons against access to hazardous
parts and protection against penetration of solid
foreign objects.
0 – Non-protected0 – Non-protected
1 – Back of hand; objects greater than 50 mm in diameter 2 – Vertically falling drops of water
3 – Finger; objects greater than 12.5 mm in diameter4 – Vertically falling drops of water with enclosure tilted 15°
5 – Tools or objects greater than 2.5 mm in diameter6 – Spraying water
7 – Tools or objects greater than1.0 mm in diameter8 – Splashing water
9 – Dust-protected (dust can enter during specified test
but must not interfere with operation of the equipment or
impair safety)
11 – Dusttight (no dust observable inside enclosure at
end of test)
Example: IP41 describes an enclosure that is designed to protect against the entry of tools or objects greater than 1 mm
in diameter and to protect against vertically dripping water under specified test conditions.
Note: All first numerals and second numerals up to and including characteristic numeral 6, imply compliance also with
the requirements for all lower characteristic numerals in their respective series (first or second). Second numerals 7 and
8 do not imply suitability for exposure to water jets (second characteristic numeral 5 or 6) unless dual coded; e.g., IP_5/ IP_7.
(1) The IEC standard permits use of certain supplementary letters with the characteristic numerals. If such letters are
used, refer to IEC 60529 for the explanation.
(1)
Second Numeral
Protection against ingress of water under test conditions
specified in IEC 60529.
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Chapter 1 Environmental Considerations
IP0_ No test required.
IP1_
A rigid sphere 50 mm in diameter shall not completely pass through any
opening. Force = 50 N.
A jointed test finger 80 mm long and 12 mm in diameter can penetrate to its
IP2_
80 mm length, but shall have adequate clearance as specified above, from
hazardous live parts, in every possible position of the test finger as both
joints are bent through an angle up to 90°. Force = 10 N.
A test rod 2.5 mm in diameter shall not penetrate and adequate clearance
IP3_
shall be kept from hazardous live parts
(as specified in Table 1
). Force = 3 N.
A test wire 1 mm in diameter shall not penetrate and adequate clearance
IP4_
shall be kept from hazardous live parts
(as specified in Table 1
). Force = 1 N.
A test wire 1 mm in diameter shall not penetrate and adequate clearance
IP5_
shall be kept from hazardous live parts
(as specified in Table 1
). Force = 1 N.
A test wire 1 mm in diameter shall not penetrate and adequate clearance
IP6_
shall be kept from hazardous live parts
(as specified in the Table 1
). Force = 1 N.
Tests for Protection Against Solid Foreign Objects (first characteristic numeral)
For first numerals 1, 2, 3, and 4, the protection against solid foreign objects is satisfactory if the full diameter of the specified probe does not
pass through any opening. Note that for first numerals 3 and 4, the probes are intended to simulate foreign objects which can be spherical.
Where shape of the entry path leaves any doubt about ingress or a spherical object capable of motion, it can be necessary to examine
drawings or to provide special access for the object probe. For first numerals 5 and 6, see test descriptions below for acceptance criteria.
IP0_ No test required.
IP1_
IP2_
IP3_
The full diameter of a rigid sphere 50 mm in diameter must not pass through
any opening at a test force of 50 N.
The full diameter of a rigid sphere 12.5 mm in diameter must not pass
through any opening at a test force of 30 N.
A rigid steel rod 2.5 mm in diameter must not pass through any opening at a
test force of 3 N.
12Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
Chapter 1 Environmental Considerations
IP4_
IP5_
IP6_
A rigid steel wire 1 mm in diameter must not pass through any opening at a
test force of 1 N.
The test specimen is supported inside a specified dust chamber where
talcum powder, able to pass through a square-mesh sieve with wire
diameter 50 mm and width between wires 75 mm, is kept in suspension.
Enclosures for equipment subject to thermal cycling effects (category 1) are
vacuum pumped to a reduced internal pressure relative to the surrounding
atmosphere: maximum depression = 2 kPa; maximum extraction rate = 60
volumes per hour. If extraction rate of 40 to 60 volumes/hr is obtained, test
is continued until 80 volumes have been drawn through or 8 hours has
elapsed. If extraction rate is less than 40 volumes/hr at 20 kPa depression,
test time = 8 hr.
Enclosures for equipment not subject to thermal cycling effects, and
designated category 2 in the relevant product standard, are tested for 8
hours without vacuum pumping.
Protection is satisfactory if talcum powder has not accumulated in a
quantity or location such that, as with any other kind of dust, it could
interfere with the correct operation of the equipment or impair safety, and
no dust has been deposited where it could lead to tracking along creepage
distances.
All enclosures are tested as category 1, as specified above for IP5_. The
protection is satisfactory if no deposit of dust is observable inside the
enclosure at the end of the test.
Tests for Protection Against Water (second characteristic numeral)
The second characteristic numeral of the IP number indicates compliance with the following tests for the degree of protection against
water. For numerals 1 through 7, the protection is satisfactory if any water that has entered does not interfere with satisfactory operation,
does not reach live parts not designed to operate when wet, and does not accumulate near a cable entry or enter the cable. For second
numeral 8, the protection is satisfactory if no water has entered the enclosure.
IP_0 No test required.
Water is dripped onto the enclosure from a “drip box” having spouts spaced
IP_1
IP_2
IP_3
IP_4 Same as test for IP_3 except spray covers an arc of 180° from vertical.
on a 20 mm square pattern, at a “rainfall” rate of 1 mm/min The enclosure is
placed in its normal operating position under the drip box. Test time = 10 min
Water is dripped onto the enclosure from a “drip box” having spouts spaced
on a 20 mm square pattern, at a “rainfall” rate of 3 mm/min The enclosure is
placed in 4 fixed positions tilted 15° from its normal operating position,
under the drip box. Test time = 2.5 min for each position of tilt.
Water is sprayed onto all sides of the enclosure over an arc of 60° from
vertical, using an oscillating tube device with spray holes 50 mm apart (or a
hand-held nozzle for larger enclosures). Flow rate, oscillating tube device =
0.07 l/min per hole x number of holes; for hand-held nozzle = 10 l/min Test
time, oscillating tube = 10 min; for hand-held nozzle = 1 min/m2 of enclosure
surface area, 5 min minimum.
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Chapter 1 Environmental Considerations
Enclosure is sprayed from all practicable directions with a stream of water
IP_5
IP_6
IP_7
IP_8
at 12.5 l/min from a 6.3 mm nozzle from a distance of 2.5 to 3 m. Test time =
1 min/m2 of enclosure surface area to be sprayed, 3 min minimum.
Enclosure is sprayed from all practicable directions with a stream of water
at 100 l/min from a 12.5 mm nozzle from a distance of 2.5 to 3 m. Test time =
1 min/m2 of enclosure surface area to be sprayed, 3 min minimum.
Enclosure is immersed in water in its service position for 30 min Lowest
point of enclosures less than 850 mm tall = 1000 mm below surface of water.
Highest point of enclosures more than 850 mm tall = 150 mm below surface
of water.
Test conditions are subject to agreement between manufacturer and user,
but shall be at least as severe as those for IP_7.
Abridged Descriptions of NEMA Enclosure Test Requirements
NEMA is a commonly recognized standards organization in North America and publishes standards for enclosures. It does not require
independent verification of these tests.
6.2 Rod Entry Test
A 3.18 mm (0.125 in.) diameter rod must not be able to enter enclosure except at locations where nearest live part is more than 102 mm (4 in.)
from an opening — such opening shall not permit a 13 mm (0.5 in.) diameter rod to enter.
6.3 Drip Test
Water is dripped onto enclosure for 30 minutes from an overhead pan having uniformly spaced spouts, one every 12,900 mm (20 in.) of pan
area, each spout having a drip rate of 20 drops per minute.
Evaluation 6.3.2.2: No water shall have entered enclosure.
6.4 Rain Test
Entire top and all exposed sides are sprayed with water at a pressure of
0.35 kg/cm2 (5 psi) from nozzles for one hour at a rate to cause water to rise 457 mm (18 in.) in a straight-sided pan beneath the enclosure.
Evaluation 6.4.2.1: No water shall have reached live parts, insulation, or mechanisms.
Evaluation 6.4.2.2: No water shall have entered enclosure.
6.5.1.1 (2) Outdoor Dust Test (Alternate Method)
Enclosure and external mechanisms are subjected to a stream of water at 170.5 liters (45 gallons) per minute from a 25.4 mm (1 in.) diameter
nozzle, directed at all joints from all angles from a distance of 3…3.7 m (10…12 ft). Test time is 48 seconds times the test length (height +
width + depth of enclosure in feet), or a minimum of 5 minutes. No water shall enter enclosure.
14Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
Chapter 1 Environmental Considerations
6.5.1.2 (2) Indoor Dust Test (Alternate Method)
Atomized water at a pressure of 2.11 kg/cm2 (30 psi) is sprayed on all seams, joints and external operating mechanisms from a distance of
305…381 mm (12…15 in.) at a rate of 11 liters (3 gallons) per hour. No less than 142 gms
(5 oz) of water per linear foot of test length (height + length + depth of enclosure) is applied. No water shall enter enclosure.
6.6 External Icing Test
Water is sprayed on enclosure for one hour in a cold room 2 °C (36 °F); then room temperature is lowered to approximately –5 °C (–23 °F) and
water spray is controlled so as to cause ice to build up at a rate of 6.4 mm (0.25 in.) per hour until 19 mm (0.75 in.) thick ice has formed on top
surface of a 25.4 mm (1 in.) diameter metal test bar, then temperature is maintained at –5 °C (–23 °F) for 3 hours.
Evaluation 6.6.2.2: Equipment shall be undamaged after ice has melted (external mechanisms not required to be operable while iceladen).
6.7 Hosedown Test
Enclosure and external mechanisms are subjected to a stream of water at 246 liters (65 gallons) per minute from a 25.4 mm (1 in.) diameter
nozzle, directed at all joints from all angles from a distance of 3…3.7 m (10...12 ft). Test time is 48 seconds times the test length [height +
width + depth] of enclosure in meters (feet), or a minimum of 5 seconds. No water shall enter enclosure.
6.8 Rust Resistance Test (Applicable Only to Enclosures Incorporating External Ferrous Parts)
Enclosure is subjected to a salt spray (fog) for 24 hours, using water with five parts by weight of salt (NaCI), at 35 °C (95 °F), then rinsed and
dried. There shall be no rust except where protection is impractical (for example, machined mating surfaces, sliding surfaces of hinges,
shafts, etc.).
6.9 Corrosion Protection
Sheet steel enclosures are evaluated per Underwriter's Laboratories (UL) 50, Part 13 (test for equivalent protection as G-90 commercial zinc
coated sheet steel). Other materials per Underwriter's Laboratories (UL) 508, 6.9 or 6.10.
6.11 (2) Air Pressure Test (Alternate Method)
Enclosure is submerged in water at a pressure equal to water depth of 2 m (6 ft), for 24 hours. No water shall enter enclosure.
6.12 Oil Exclusion Test
Enclosure is subjected to a stream of test liquid for 30 minutes from a 9.5 mm (0.375 in.) diameter nozzle at 7.57 liters (2 gallons) a minute.
Water with 0.1% wetting agent is directed from all angles from a distance of 305…457 mm (12…18 in.), while any externally operated device is
operated at 30 operations per minute. No test liquid shall enter the enclosure.
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Chapter 1 Environmental Considerations
Abridged Descriptions of UL Standard 698 Test Requirements
The following descriptions are based on the descriptions in the UL Standard 698 Test Requirements.
Explosion Test
During a series of tests in which gas-air mixtures of the specific gas, over its range of explosive concentrations, are ignited inside the
enclosure, the enclosure shall prevent the passage of flame and sparks capable of igniting a similar gas-air mixture surrounding the
enclosure. In addition, there shall be no mechanical damage to enclosed electrical mechanisms or the enclosure.
Hydrostatic Test
The enclosure shall withstand for one minute a hydrostatic test based on the maximum internal explosion pressure developed during the
explosion tests, as follows: cast metal, four times the explosion pressure without rupture or permanent deformation; fabricated steel, twice
the explosion pressure without permanent deformation and three times the explosion pressure without rupture. Exception: Hydrostatic tests
can be omitted if calculations show safety factor of 5:1 for cast metal, and 4:1 for fabricated steel.
Temperature Test
The enclosed device is subjected to a temperature test to determine maximum temperature at any point on the external surface. The device
must be marked with a temperature code based on the result only if the temperature exceeds 100 °C (212 °F).
Dust Penetration Test
The device is operated at full rated load until equilibrium temperatures are attained, then allowed to cool to ambient (room) temperature,
through six heating and cooling cycles covering at least 30 hours, while continuously exposed to circulating dust of specified properties in a
test chamber. No dust shall enter the enclosure.
Temperature Test with Dust Blanket
This test is conducted as described for the Dust Penetration test except that the re-circulating dust nozzles are positioned so that the dust
is not blown directly on the device under test. The device is operated at full rated load (and under abnormal conditions for equipment subject
to overloading) until equilibrium temperatures are attained. Dust in contact with the enclosure shall not ignite or discolor from heat, and the
exterior surface temperatures based on 40 °C (104 °F) ambient shall not exceed the values listed below.
Class II, GroupNormal Operating ConditionsAbnormal Operating Conditions
E200 °C (392 °F)200 °C (392 °F)
F150 °C (302 °F)200 °C (392 °F)
G120 °C (248 °F)165 °C (329 °F)
Enclosure Type Descriptions
This section provides enclosure type descriptions for hazardous and non-hazardous locations.
16Rockwell Automation Publication DRIVES-AT003C-EN-P - October 2020
Chapter 1 Environmental Considerations
Type 1 – General Purpose Surface Mounting
Type 1 enclosures are intended for indoor use primarily to provide a degree of protection against contact with the enclosed
equipment in locations where unusual service conditions do not exist. The enclosures are designed to meet the rod-entry and
rust-resistance design tests. Enclosure is sheet steel, treated to resist corrosion.
Type 1 – Flush Mounting
Type 1 Flush Mounting enclosures for installation in machine frames and plaster wall. These enclosures are for similar applications and are
designed to meet the same tests as Type 1 surface mounting.
Type 3 – Rainproof Dusttight
Type 3 enclosures are intended for outdoor use primarily to provide a degree of protection against windblown dust, rain, and sleet; and to
be undamaged by the formation of ice on the enclosure. They are designed to meet rain
(1)
, external icing
tests. They are not intended to provide protection against conditions such as internal condensation or internal icing.
(2)
, dust, and rust-resistance design
Type 3R – Rainproof
Type 3R enclosures are intended for outdoor use primarily to provide a degree of protection against falling rain, and to be undamaged by
the formation of ice on the enclosure. They are designed to meet rod entry, rain
(3)
external icing
(4)
, and rust resistance design tests. They are
not intended to provide protection against conditions such as dust, internal condensation, or internal icing.
Type 4 – Watertight
Type 4 enclosures are intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust
and rain, splashing water, and hose-directed water; and to be undamaged by the formation of ice on the enclosure. They are
(4)
designed to meet hosedown, dust, and external icing tests
. They are not intended to provide protection against conditions
such as internal condensation or internal icing.
Type 4X – Non-metallic, Corrosion-resistant
Type 4X enclosures are intended for indoor or outdoor use primarily to provide a degree of protection against corrosion,
windblown dust and rain, splashing water, and hose-directed water; and to be undamaged by the formation of ice on the
(4)
enclosure. They are designed to meet the hosedown, dust, external icing
not intended to provide protection against conditions such as internal condensation or internal icing.
, and corrosion-resistance design tests. They are
(1) Evaluation criteria: No water has entered enclosure during specified test.
(2) Evaluation criteria: Undamaged after ice buildup during specified test has melted. (Note: Not required to be operable while iceladen.)
(3) Evaluation criteria: No water shall have reached live parts, insulation or mechanisms.
(4) Evaluation criteria: Undamaged after ice buildup during specified test has melted. (Note: Not required to be operable while iceladen.)
Rockwell Automation Publication DRIVES-AT003C-EN-P - October 202017
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