(Confidential – For Internal Use Only)

Copyright © 2009 Rockwell Automation, Inc. All rights reserved.

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SCCRApplying High Fault Ratings

Component HOTT

Why is SCCR important?

• OSHA – law requires that owners provide a safe workplace for there employees

• Installation codes require installing a panel within the available fault level available. Ref: NEC70 section 110.11

• End Users are specifying panels with specific SSCR ratings.• Large users with multiple facilities are standardizing on panels

with specific SCCR ratings. • End Users are now doing system studies of there facilities (ex. Arc

Flash) and now know the level of fault current available. • OEMs, Panel Builders will offer higher rated panels to differentiate

themselves from there competitors

Industrial Control Panels Requirements

• All panels installed must be marked – This is an electrical code requirement NEC 70 ( 2005 or later) – Responsibility of the installer (contractor or owner of the facility)

• Marking

Evaluating the Panel – How it works

• Evaluate the 3 areas of the panel – Feeder Section – Control Circuit – Branch Circuits

The lowest rating of any of the following will determine the rating of the whole panel.

• Any power component in the Feeder Section• The circuit protection device protecting the control circuit. • The branch circuit rating

• Components that do not require evaluation• Power Transformers, Reactors, Current Transformers, Dry-type

capacitors, resistors, varistors and volt meters

Locating Feeder Circuit Components

Indentify Components in the feeder1. Find all of the last branch circuit protection

devices.2. All components above the branch circuit

protection device are feeder components 3. Include passive components such as bus

bars and power distribution blocks.

“Feeder Circuit”“Branch” CPD

Branch Circuit ComponentsBranch Circuit protection device

Identifying Branch Circuit Components

Identifying the Branch Circuit Find all of the last branch circuit protection

devices.1. All components below each branch circuit

protection device are components in the branch circuit.

2. Include passive components such terminal blocks

Control Circuit ComponentsBranch Circuit protection device

Identifying the Control Circuit

Identifying the Control Circuit

1. The branch circuit protection device is the only component evaluated.

2. Control Circuits can be tapped from the main supply or stepped down using a control circuit transformer

Indentify the 3 areas of a panel

Panel Evaluation Method

How to evaluate Branch Circuits

1. Determine the rating of the power components in the branch

2. Compare each component to the branch circuit protection device

3. Label the branch the lowest of the two ratings

10kA 100kA

5kA

65kA100kA

65kA

5kA

5kA 10kA 65kA

Applying High Fault Ratings

• High fault Rating– A SCCR rating based on being

tested with a specific branch circuit protected device

– This is a conditional rating based on optional manufacturer’s testing

– An alternative to using individual ratings that limit the overall marking of the panel.

10kA

5kA

65kA100kA

5kA

65kA 70kA

Individual Ratings

High Fault Ratings

How to you find SCCR Product Data

Product Label or Installation Instructions Example NEMA 509 Starter

Minimum SCCR Rating

High Fault Rating

Required Branch Circuit Protection Device

Tools available to find SCCR ratings?

• Combination Motor Controllers– Catalog or UL website for manufacturers who build using discrete components– Product Selection Toolbox

• Disconnects, Circuit Breakers 194R, 140U, 140M– Catalog, Product Selection Toolbox

• PowerFlex Drives – User Manual, Technical Data Publications 22td

• Solid State Motor Controllers 150– Catalog, SPD software Utility

• Power Distribution Blocks 1492-PD– Product Selection Toolbox, Technical Data 1492-TD013_EN_.pdf

• Terminal Blocks 1492-J– Product Selection Toolbox, UL File Report

How to you find SCCR Product Data

• Products with No Ratings get assigned a minimum Ratings or Assigned Values from UL508A SB4 table

(Confidential – For Internal Use Only)

Copyright © 2009 Rockwell Automation, Inc. All rights reserved.

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