Specifications

PIP ELCGL01
Electrical Design Criteria November 2002
Page 10 of 20 Process Industry Practices
5.3 Transformers
5.3.1 The system power transformers shall be selected as specified on the Data
Sheet.
5.3.2 Transformers shall be sized according to the designed operating load on the
substation. Liquid-filled transformers shall be sized based on their 65°C
rating, unless otherwise specified on the Data Sheet. Dry type transformers
shall be sized based on their 80°C rating. If the forced-cooled rating will be
required for future load growth, provisions shall be made for the future
addition of fans.
5.3.3 For double-ended substations (or similar arrangements having more than one
transformer serving interconnected buses), in which one transformer is out of
service, the remaining transformer(s) shall have sufficient capacity at the
highest temperature rise FA rating to serve the maximum designed operating
load on the substation.
5.3.4 Liquid-filled transformers shall be filled with mineral-based dielectric oil
unless specified otherwise on the Data Sheet.
5.3.5 System power transformers shall be located outdoors unless indicated
otherwise on the Data Sheet. Outdoor transformers shall be specified per
PIP ELSTR01 unless specified otherwise on the Data Sheet. Indoor
transformers shall be specified per PIP ELSTR03 unless specified otherwise
on the Data Sheet.
5.3.6 Unless specified otherwise on the Data Sheet, control power and lighting
transformers shall be indoor, 80°C rise with 220°C insulation.
5.3.7 If specified on the Data Sheet, outdoor control power and lighting
transformers shall be epoxy-encapsulated.
5.3.8 Fire protection for mineral-oil-filled transformers shall conform to the
requirements of IEEE 979-1994, Sections 1, 3, and 4. Containment and spill
control for mineral-oil-filled transformers shall conform to the requirements
of IEEE 980-1994, Sections 1, 2, 3, 4, 5.4, 6, 7, 8.2.2.2, 8.3, and 8.4.
5.4 Metering, Monitoring, and Relaying
5.4.1 Metering shall incorporate microprocessor-based multifunction devices
unless specified otherwise on the Data Sheet.
5.4.2 When specified on the Data Sheet, metering and protective devices shall
have digital communication capabilities.
5.4.3 Protective relaying shall incorporate microprocessor-based multifunction
devices unless specified otherwise on the Data Sheet.
5.5 Switchgear
5.5.1 Low-voltage switchgear shall be metal-enclosed drawout type as specified in
PIP ELSSG01 unless specified otherwise on the Data Sheet.