Flexi -3G Installation & Commissioning Manual
Chapter 7. Installation of DC Cables
Page 64 of 94
Document No: - 4493-CM-EN-10989402
Copyright © 2008-2009 Eaton Corporation. All Rights Reserved
7.1. DC Distribution
7.1.1. Load MCB’s
The maximum quantity of load MCB’s in the Power Cabinet is up to 22 x 18mm load
MCB’s.
A range of MCB ratings are available. Contact Eaton for further information (refer to
section 1.5. Contact Information on page 6).
The Power Supply Unit is POSITIVE EARTH. Ensure that the correct polarity is observed
throughout.
7.1.2. Fitting MCBs
1.
Check that all MCBs are switched off.
2.
Loosen the terminals on the new MCB and clip onto the DIN rail.
3.
Secure the MCB to the DIN rail with the clip.
When fitting cables to <25A type MCBs, tighten terminals to 2.5Nm.
When fitting cables to >25A type MCBs, tighten terminals to 3.5Nm.
7.1.3. De-rating factors for Cables and MCBs
The following information relates to the de-rating factors that mustr be applied to MCBs and
cables used in Flex – 3G Power Cabinets.
7.1.3.A. MCB Grouping
MCBs used Side by side (grouped) must be de-rated by a factor of 0.8.
7.1.3.B. Temperature de-rating for MCBs
Ambient temperature is measured outside of the Power Box, near to the air inlet.
De-rating assumes that the system is running at full load.
7.1.3.B.i. Chint manufactured MCBs
Chint NB1 up to 63A
Ambient
Temp
0
˚
C 10
˚
C 20
˚
C 30
˚
C 40
˚
C
De-rating
Factor
1.04 1.00 0.96 0.93 0.88
Chint DZ158 up to 125A
Ambient
Temp
0
˚
C 10
˚
C 20
˚
C 30
˚
C 40
˚
C
De-rating
Factor
1.05 1.00 0.95 0.93 0.82
40˚C ambient is the maximum limit for cabinets using Chint MCBs.
