How to chose the right UL SPD Type for your UL508A Control Panel

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UL508A Industrial Control Panels Standard

UL508A Main
UL508A Industrial Control Panel

Overview

In North America, UL approval provides independent 3rd Party certification that a product has been tested by Underwriters Laboratories (UL) or another Nationally Recognized Testing Laboratory (NRTL) and meets all necessary electric code safety requirements as well as industry benchmarks.

On April 13, 2020, UL released a UL508A supplement document titled "REQUIREMENTS FOR COMPONENTS USED IN INDUSTRIAL CONTROL PANELS" that was published with the intent to help control panel builders determine the requirements for components when used in industrial control panels. The document replaces what was Supplement SA in the Second Edition of UL508A, and subsequently Appendix C in the Third Edtition of UL508A. It supersedes the previous verion of this document dated October 21, 2019.

Remote VFD Control Panel

UL, in the form of the UL inspector, will carefully consider many factors while determing the fitness of the Surge Protective Device (SPD) for the equipment that is being evaluated for UL compliance. It is critically important to understand the process that UL will use to evaluate the SPD according to UL508A.

Each component belongs to individual Category that describes the specific requirements of the component. In a UL508A Industrial Control Panel, the Surge Protective Device will be evaluated based on Sections 36, 47, and 75. These sections are referenced in Table 1 of the Supplement document.

Table 1 - Components that comply with specific requirements

UL508A Section/Paragraph Reference
Section 36 - Miscellaneous power devices meeting component selection requirements
UL508A
Paragraph
reference
Component descriptionUL StandardCategory
control
number(s)
Notes
36.4.1Recognized Surge
Protective
Devices
UL 1449VZCA2SPDs that are outside the guidelings of Table 2 must be procedure described
36.4.1Listed Surge
Protective
Devices
UL 1449VZCAType 1, 2 or 3 SPDs that are outside the guidelines of Table 2 must be procedure described
Section 47 - Surge control devices meeting component selection requirements
UL508A
Paragraph
reference
Component descriptionUL StandardCategory
control
number(s)
Notes
47.1.1Recognized Surge
Protective
Devices
UL 1449VZCA2SPDs that are outside the guidelings of Table 2 must be procedure described
47.1.1Listed Surge
Protective
Devices
UL 1449VZCAType 1, 2 or 3 SPDs that are outside the guidelines of Table 2 must be procedure described
47.1.3Listed isolated Loop Circuit ProtectorsUL 479BQVGQ-
47.1.3Recognized isolated Loop Circuit ProtectorsUL 479BQVGQ2Procedure described
Section 75 - Service Equipment Use - components meeting specific selection requirements
UL508A
Paragraph
reference
Component descriptionUL StandardCategory
control
number(s)
Notes
75.8.4Surge
Protective
Devices
UL 1449VZCAType 1 SPD Only

The first step in determining the acceptability of the SPD for a given application or piece of equipment is to consider the UL SPD Type. This is the case for UL 508A as well as all other UL Listed equipment. This first level compliance is based on the UL Approval (LISTED UL logo png or RECOGNIZED UR logo png ) of the SPD or UL SPD Type and it’s Suitable Ratings. This means that the SPD has met all safety, performance, environmental and electrical system ratings of the application.

If any of these criteria are not fully met, it will require a Procedure Description, a File Update and/or Additional Testing. These actions will require additional costs that may be substantial. For this reason, it is in the interest of the specifier to use UL LISTED UL logo png SPD (Type 1 or Type 2) to eliminate any uncertainty or to make sure the UL RECOGNIZED UR logo png SPD (Type 1CA, Type 2CA, Type 4CA, Type 5) is selected at the initial UL evaluation of the control panel or at the submittal of the equipment to UL for compliance testing.

Table 2 - Use of Surge Protective Devices

Type of Surge Protective Device (SPD) - One port only*
Listed Type 1Listed Type 2Listed Type 3R/C
Type 4
Component
Assembly
R/C Type 5
Location of the SPD
Service Equipment Supply Side of Overcurrent Protectionwzzzz
Service Equipment Load Side of Overcurrent Protectionwwzzz
Non-Service Equipment Feeder or Branch Circuitswwwzz
Isolated Control Circuitswwwww
Ratings
Service Equipment Supply Side of Overcurrent ProtectionVbxzzzz
In cyzzzz
Service Equipment Load Side of Overcurrent ProtectionVbxxzzz
In cy10kAzzz
Non-Service Equipment Feeder or Branch CircuitsVbxxxzz
In cyyyzz
Isolated Control CircuitsVbxxxxx
In cyyy3kA3kA
NOTES
(1)A "w" indicates an allowable location for the SPD.
(2)An "x" indicates indicates a Normal Operating Voltage Rating is required as specified in footnote "b" below.
(3)A "y" indicates indicates a Nominal Discharge Current Rating as specified in footnote "c" below is not required.
(4)A "z" indicates the SPD nees further evaluation to determine suitability and Procedure description is required.
(a)A Two-Port SPD shall be Listed and comply with the ratings specified above for the intended application. In addition, it shall have an appropriate short circuit current rating (SCCR) rating.
(b)V - Normal Operating Voltage Rating - Operating Voltage and MCOV ratings shall be equal to or greater than the applied circuit Line-to-Line (full phase) voltage.
(c)In (NDC) - Nominal Discharge Current - Amount of peak current "forced" through the device during Surge Testing.

To help control panel builders select the right SPD based on the UL508A Industrial Control Panels standard, CITEL Citel C , in consultation with Underwriters Laboratories (UL), has made this quick reference table. If you have any questions on how to use this table or any technical and compliance questions, please contact CITEL.

Approval Considerations based on UL SPD Type

UL
Mark
UL1449
SPD Type
Suitable
Ratings
Procedure
Described
File
Update or
Additional
Testing
Notes
UL logo png 1

2
YesNoNoThe only requirement is that the SPD must match electrical and environmental ratings of the UL 508A Control Panel.

A UL field inspection of the control panel with the SPD installed is required as a part of a standard follow-up service visit.
UR logo png 1CA

2CA

4CA

5
YesYesYesYes – All UL recognized SPD’s require a UL engineering evaluation of the SPD’s existing UL1449 E–file.

This will result, at a minimum, in a cost to update the UL file and may also require testing that would result in additional costs.

CITEL Citel C UL LISTED UL logo png SPD meeting all requirements of UL508A

The following is a list of products for each section. They are UL Listed SPD and require only that they meet the "Suitable Rating" of the control panel. They can be used in all UL locations including,

  • Service Equipment Supply Side of Overcurrent Protection
  • Service Equipment Load Side of Overcurrent Protection
  • Non-Service Equipment Feeder or Branch Circuits
  • Isolated Control Circuits
UL508A
Paragraph
reference
Component
description
UL StandardCategory
control
number(s)
SystemPart #Link
36.4.1
Miscellaneous
power devices
Listed
Surge
Protective
Devices
UL 1449VZCA120Vac
1-Phase
2W+G
Single Phase
DS72US-120S/G DS72US-120S/G
120-240Vac
1-Phase
2W+G
Single Phase
DS72US-240T/NN DS72US-240TNN
120/240Vac
1-Phase
3W+G
Split Phase
DS73US-120T/G DS73US-120T-G
120/208Vac
3-Phase
4W+G
Wye
DS74US-120Y/G DS74US-277Y/G
277/480Vac
3-Phase
4W+G
Wye
DS74US-277Y/G DS74US-277Y/G
480Vac
3-Phase
3W+G
Delta
DS74US-480D DS74US-480D
47.1.1
Surge
control devices
Listed
Surge
Protective
Devices
UL 1449VZCA120Vac
1-Phase
2W+G
Single Phase
DS72US-120S/G DS72US-120S/G
120-240Vac
1-Phase
2W+G
Single Phase
DS72US-240T/NN DS72US-240TNN
120/240Vac
1-Phase
3W+G
Split Phase
DS73US-120T/G DS73US-120T-G
120/208Vac
3-Phase
4W+G
Wye
DS74US-120Y/G DS74US-277Y/G
277/480Vac
3-Phase
4W+G
Wye
DS74US-277Y/G DS74US-277Y/G
480Vac
3-Phase
3W+G
Delta
DS74US-480D DS74US-480D
47.1.3
Surge
control devices
Listed
isolated Loop
Circuit Protectors
UL 479BQVGQRS422 DLA-06D3 DLA-24D3 v.2
RS232
RS485
DLA-12D3 DLA-24D3 v.2
4-20mA
Current Loop
DLA-24D3 DLA-24D3 v.2
48Vdc DLA-48D3 DLA-24D3 v.2
75.8.4
Service
Equipment Use
Surge
Protective
Devices
UL 1449VZCA120Vac
1-Phase
2W+G
Single Phase
DS72US-120S/G DS72US-120S/G
120-240Vac
1-Phase
2W+G
Single Phase
DS72US-240T/NN DS72US-240TNN
120/240Vac
1-Phase
3W+G
Split Phase
DS73US-120T/G DS73US-120T-G
120/208Vac
3-Phase
4W+G
Wye
DS74US-120Y/G DS74US-277Y/G
277/480Vac
3-Phase
4W+G
Wye
DS74US-277Y/G DS74US-277Y/G
480Vac
3-Phase
3W+G
Delta
DS74US-480D DS74US-480D

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