Delta Electronics CTA4 User Manual download pdf (Page 1)

Data Bulletin

2700DB0202R03/12

09/2012

Replaces 2700DB0202R2/09 dated 02/2009

Corner-Grounded Delta (Grounded B Phase) Systems

Class 2700

Retain for future use.

™

ENGLISH

Introduction Corner-grounded delta systems are not recommended for new installations.

However, some utilities still provide this system, and many old installations

still exist. Schneider Electric has tested equipment for use on

corner-grounded delta systems to provide Underwriters Laboratories Inc.

(UL

) listed products for this application.

This document outlines the background of corner-grounded delta systems

and lists the equipment rated for use on these systems.

Background In the past, delta-delta connected transformers were extensively used in

electrical distribution systems. With this type of system, it was practical to

continue distributing three-phase power while performing maintenance on one

unit of the three-phase transformer bank. Now, with the advent of more reliable

modern transformers and the popularity of three-phase units, the delta-delta

connected transformer no longer has the advantage it had in the past.

One of the disadvantages of the delta-delta system is the absence of an

intentional connection to ground on the transformer secondary. To obtain a

grounded system, one of the corners of the delta secondary is grounded.

With decreased usage of the delta-delta connected transformer and

increased usage of delta-wye connected transformers, the corner-grounded

delta is rarely applied in modern systems.

Definitions

Corner-Grounded Delta System A system in which the transformer secondary is delta-connected with one

corner of the delta solidly grounded. Corner-grounded delta systems are

also referred to as grounded B phase systems, grounded phase services,

and end-grounded delta systems.

Ungrounded System A system without an intentional connection to ground, except through

potential indicating or measuring devices.

Grounded System A system that has at least one conductor or point intentionally connected to

ground, either solidly or through an impedance.

Solidly Grounded An intentional connection made directly to ground without inserting any

resistor or impedance.

Figure 1: System Diagram, 3Ø3W Ground BØ Delta

1 2 3 4 5 6 7 8

Summary of Contents

Page 1 - Data Bulletin

Data Bulletin2700DB0202R03/1209/2012Replaces 2700DB0202R2/09 dated 02/2009Corner-Grounded Delta (Grounded B Phase) SystemsClass 2700Retain for future

Page 2 - Standards 09/2012

Page 3 - Voltages

Page 4 - Theory 09/2012

Page 5

Page 6

Page 7 - Equipment

Page 8

Corner-Grounded Delta (Grounded B Phase) Systems 2700DB0202R03/12References 09/2012Electrical equipment should be installed, operated, serviced, and

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Delta Electronics CTA4 User Manual Page 1

Browse online or download User Manual for Unknown Delta Electronics CTA4. Data Bulletin Corner-Grounded Delta

Summary of Contents

Comments to this Manuals

Delta Electronics CTA4 User Manual Page 1

Browse online or download User Manual for Unknown Delta Electronics CTA4. Data Bulletin Corner-Grounded Delta

Summary of Contents

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