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2.4 Enclosure Types
The VLT Series adjustable frequency drives are available
in various enclosure types to best accommodate the
needs of the application. Enclosure ratings are provided
based on two international standards:
•
NEMA (National Electrical Manufacturers
Association) in the United States
•
IP (International Protection) ratings outlined by
IEC (International Electrotechnical Commission) in
the rest of the world
Standard Danfoss VLT adjustable frequency drives are
available in various enclosure types to meet the
requirements of IP00 (chassis), IP20, IP21 (NEMA 1), or IP54
(NEMA12).
UL and NEMA Standards
NEMA/UL Type 1
– Enclosures constructed for indoor use
to provide a degree of protection to personnel against
incidental contact with the enclosed units and to provide a
degree of protection against falling dirt.
NEMA/UL Type 12
– General purpose enclosures are
intended for use indoors to protect the enclosed units
against the following contaminants:
•
fibers
•
lint
•
dust and dirt
•
light splashing
•
seepage
•
dripping and external condensation of non-
corrosive liquids
There can be no holes through the enclosure and no
conduit knockouts or conduit openings, except when used
with oil-resistant gaskets to mount oil-tight or dust-tight
mechanisms. Doors are also provided with oil-resistant
gaskets. In addition, enclosures for combination controllers
have hinged doors, which swing horizontally and require a
tool to open.
UL type validates that the enclosures meet NEMA
standards. The construction and testing requirements for
enclosures are provided in NEMA Standards Publication
250-2003 and UL 50, Eleventh Edition.
IP Codes
provides a cross-reference between the two
standards.
demonstrates how to read the IP
number code and defines the levels of protection. The
adjustable frequency drives meet the requirements of
both.
NEMA type
IP type
Chassis
IP00
Protected chassis
IP20
NEMA 1
IP21
NEMA 12
IP54
Table 2.3 IP Number Cross Reference
First digit (solid foreign objects)
0
No protection
1
Protected to 50 mm (hands)
2
Protected to 12.5 mm (fingers)
3
Protected to 2.5 mm (tools)
4
Protected to 1.0 mm (wire)
5
Protected against dust – limited entry
6
Protected totally against dust
Second digit (water)
0
No protection
1
Protected from vertical dripping water
2
Protected from dripping water at 15° angle
3
Protected from water at 60° angle
4
Protected from splashing water
5
Protected from water jets
6
Protected from strong water jets
7
Protected from temporary immersion
8
Protected from permanent immersion
Table 2.4 IP Number Code Definitions
Safety and Conformity
Design Guide
MG34S222
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
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