Nortel DMS-100 Series User manual

Applies to all BCS and PCL levels Standard 02.02 August 1997
297-1001–350
DMS-100 Family
Digital Switching Systems
Power and Grounding Routine Maintenance
Manual

DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
Digital Switching Systems
DMS-100 Family
Power and Grounding Routine Maintenance Manual
1988, 1989, 19941997 Northern Telecom
All rights reserved.
Printed in Canada and printed in the United States of America.
NORTHERN TELECOM CONFIDENTIAL: The information contained in this document is the property of Northern
Telecom. Except as specifically authorized in writing by Northern Telecom, the holder of this document shall keep the
information contained herein confidential and shall protect same in whole or in part from disclosure and dissemination to third
parties and use same for evaluation, operation, and maintenance purposes only.
Information is subject to change without notice. Northern Telecom reserves the right to make changes in design or components
as progress in engineering and manufacturing may warrant.
DMS
, DMS-100, NT, are trademarks of Northern Telecom. DIGISNAP is a trademark of the A. W. Sperry Instruments, Inc. HP
is a trademark of the Hewlett-Packard Co.
Publication number: 297-1001-350
Product release: Applies to all BCS/PCL levels
Document release: Standard 02.02
Date: August 1997

DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
iii
Publication history
August 1997 Standard 02.02 was issued to incorporate editiorial markup and customer
feedback.
June 1994 Standard 02.01 was issued for the following reasons:
•to compose NTP 297-1001-350 in a new typographical style
(restructured format).
•to comply with the generic design intent, terminology, and definitions
of applicable Northern Telecom Corporate Standards and NTP
297-1001-156, DMS-100 Family Power Distribution and Grounding
Guide
•to improve the composition, arrangement, and structure of the content
•to simplify and improve the text, figures, and tables.
March 1989 Standard 01.04 was issued for technical corrections and replaced all
previous releases.

DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
Draft: June 2, 1993
v
Contents
About this document ix
Application of this document ix
References ix
Prerequisite references x
Informative references x
1 Introduction 1–1
1.1 Definitions 1–1
battery return (BR): 1–1
battery return reference (BRR): 1–1
bonding: 1–1
bonding network (BN): 1–1
building principal ground (BPG): 1–1
common bonding network (CBN): 1–1
DMS-100 Family: 1–2
DMS single point ground (DMS SPG): 1–2
floor ground bar (FGB): 1–2
framework bonding bar (FBB): 1–2
framework bonding equalizer (FBE) bar: 1–2
framework ground bus: 1–2
ground: 1–3
incidental ground: 1–3
isolated bonding network (IBN): 1–3
isolated system grounding (ISG): 1–3
isolation: 1–3
logic return bar (LRB): 1–3
logic return equalizer (LRE) bar: 1–3
single point ground (SPG): 1–4
vertical ground riser (VGR): 1–4
vertical logic return bar: 1–4
1.2 Abbreviations and acronyms 1–4
1.3 Cross reference of terms 1–6
2 Overview 2–1
2.1 DC power 2–1
2.2 AC power 2–1
2.3 Grounding 2–1
3 Power system maintenance 3–1
3.1 Preparations 3–1

vi Contents
297-1001-350 Standard 02.02 August 1997
Draft: June 2, 1993
3.1.1 Maintenance records 3–1
3.1.2 Maintenance action record 3–17
3.1.3 Tools 3–17
3.2 Power plant critical limits 3–18
3.3 Power plant maintenance schedule 3–19
3.4 Power plant checks 3–20
3.5 Power plant safety checks 3–21
3.6 Power plant fuse checks 3–22
3.7 Charging equipment checks 3–22
3.8 Battery equipment checks 3–24
3.8.1 Maintenance intervals 3–24
3.8.2 Trouble conditions 3–26
3.8.3 Post connections 3–26
3.8.4 Positive plate growth 3–26
3.8.5 Post corrosion 3–27
3.8.6 Electrolyte level and temperature 3–32
3.8.7 Water analysis report 3–32
3.8.8 Avoiding battery trouble 3–33
3.9 Standby power system checks 3–34
3.10 Standby engine-alternator checks 3–35
3.11 Standby power system exercise 3–36
3.11.1 Precautions 3–36
3.11.2 Preparations 3–37
3.11.3 Procedure 3–38
3.12 Miscellaneous power plant checks 3–41
3.13 Submitting the maintenance report 3–42
4 Grounding system maintenance 4–1
4.1 Grounding system diagrams 4–1
4.2 Tools required 4–1
4.3 Building principal ground (BPG) checks 4–2
4.4 Ground resistance test 4–3
4.5 Floor ground bar (FGB) checks 4–3
4.6 Power plant grounding checks 4–4
4.7 AC grounding checks 4–4
4.7.1 AC-free DMS switch 4–4
4.7.2 Other DMS switch versions 4–5
4.8 DMS SPG checks 4–5
4.9 Framework bonding equalizer (FBE) checks 4–6
4.10 Framework ground bus checks 4–7
4.11 Logic return equalizer (LRE) checks 4–8
4.12 Logic return bar (LRB) checks 4–9
4.13 Bonding within DMS cabinets/frames 4–9
4.14 Cable entrance ground bar (CEGB) checks 4–9
4.15 Main distribution frame/protector frame checks 4–10
4.16 Cleaning corroded grounding connections 4–11
4.17 Grounding audit 4–12
List of figures
Figure 3–1 Sample pilot cell voltage and specific gravity test record 3–3

Contents vii
DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
Draft: June 2, 1993
Figure 3–2 Sample battery electrical and specific gravity measurements
record 3–4
Figure 3–3 Sample charging plant capacity and reserves data record 3–5
Figure 3–4 Sample telephone number record 3–6
Figure 3–5 Standby engines—office loads and battery reserves record 3–7
Figure 3–6 Sample power plant alarm check record 3–8
Figure 3–7 Sample log sheet for stationary alternator routine engine runs
3–9
Figure 3–8 Sample log sheet for mobile alternator routine engine runs
3–10
Figure 3–9 Sample standby power system exercise evaluation report 3–11
Figure 3–10 Standby power system exercise control log 3–12
Figure 3–11 Standby power system exercise—stationary engine-alternator
log 3–13
Figure 3–12 Standby power system exercise—mobile engine-alternator log
3–14
Figure 3–13 Battery load test record 3–15
Figure 3–14 Power plant maintenance action required 3–16
Figure 3–15 Typical internal parts of a battery 3–29
Figure 3–16 Positive plate growth 3–30
Figure 3–17 Battery post and intercell connector corrosion 3–31
List of tables
Table 1–1 Cross reference of terms 1–6
Table 3–1 Power plant maintenance schedule 3–19
Table 3–2 Power plant data, monitored conditions 3–23
Table 3–3 Schedule of battery readings and work intervals 3–25
Table 3–4 Maximum allowable impurities in battery water 3–33
Table 3–5 Recommended battery load test duration 3–40

DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
ix
About this document
This document contains maintenance procedures for checking the power and
grounding installation for DMS-100 Family (DMS-100F) switch equipment.
The power-related maintenance procedures include various checks of the
DMS battery plant and rectifiers, an operational exercise of the standby
power system, and a method for removing and restoring power in an
emergency situation.
Application of this document
It is written for personnel having responsibility for plant-equipment
maintenance, installation, engineering, and planning. This guide is based
upon the principles developed in Northern Telecom Corporate Standards.
More than one version of this document may exist. To determine whether
you have the latest version of this document, check the release information
in DMS-100 Family Guide to Northern Telecom Publications,
297-1001-001.
References References listed as prerequisites are essential for understanding this
document. Those listed as informative contain additional information,
but are not essential.
More than one version of a document may exist. To determine whether
you have the latest version of a document, check the release information in
DMS-100 Family Guide to Northern Telecom Publications,297-1001-001.
Some NTPs, supporting all PCLs and previous BCS releases, have not been
updated with market specific information. NTPs with such an applicability
statement and containing cross-references must be cross-checked against
information in the DMS-10 and DMS-100 Cancellation Cross-reference
Directory (297–8991–002)

xAbout this document
297-1001-350 Standard 02.02 August 1997
Prerequisite references
•NTP 297-1001-156: DMS-100 Family Power Distribution and
Grounding Guide
•TR-NWT-000295: Bell Communications Research Technical Reference,
Isolated Ground Planes; Definition and Application
to Telephone Central Offices
•Rural Electrification Administration (REA) Telecommunications
Engineering and Construction Manual,
Section 810: Electrical Protection of Electronic
Analog and Digital Central Office Equipment
•ANSI/NFPA No. 70: National Electrical Code—1990
•CSA C22.1: Canadian Electrical Code—1990
Informative references
•NTP 297-1001-001: DMS-100 Family Guide to
Northern Telecom Publications
•NTP 297-1001-120: Equipment Identification
•IS0X00: Isolated Systems Grounding Topology
•IS0X07ZA: Digital Multiplex System AC Grounding
•Federal Information Processing Standard (FIPS) Pub 94: Guideline on
Electrical Power for ADP Installations
•ANSI/NFPA No. 75: Protection of Electronic Computer/Data
Processing—1989
•ANSI/NFPA No. 78: Lightning Protection Code—1989

DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
1–1
1 Introduction
The following definitions conform as closely as possible to those of the
National Electrical Code (NEC) and the Canadian Electrical Code (CEC).
1.1 Definitions
battery return (BR):
A conductor that carries the –48 V return current. Although BR conductors
are not grounding conductors, they are referenced to ground by the battery
return reference (BRR) conductor of the serving dc power plant.
battery return reference (BRR):
A grounding conductor used to connect battery return to ground.
bonding:
The permanent joining of non-current carrying metallic parts to form an
electrically conductive path, which ensures electrical continuity and the
capacity to safely conduct any current likely to be imposed upon the path.
bonding network (BN):
A set of interconnected conductive structures that provides an
electromagnetic shield for electronic systems and personnel at frequencies
from dc to low rf. The term electromagnetic shield denotes any structure
used to divert, block, or impede the passage of electromagnetic energy. In
general, a BN need not be connected to earth, but all BNs considered in this
document require an earth connection.
building principal ground (BPG):
The main point within a building at which the ground reference potential is
established. The BPG is directly referenced to earth by such means as water
pipes and/or electrodes driven into the earth.
common bonding network (CBN):
The principal means used for bonding and grounding inside a
telecommunications building. It is the set of metallic components that are
intentionally or incidentally interconnected to form the principal bonding
network in a building. These components include: structural steel or

1–2 Introduction
297-1001-350 Standard 02.02 August 1997
reinforcing rods, metallic plumbing, ac power conduit, ac equipment
grounding conductors, bonding conductors, and cable racks. The CBN is a
mesh topology and is connected to the building grounding electrode system.
DMS-100 Family:
Designates the family of digital multiplexed switching systems which
include the DMS-100, DMS-100/200, DMS-100 switching cluster,
DMS-100 switching network, DMS-200, DMS-250, and DMS-300.
DMS single point ground (DMS SPG):
A single point where the framework bonding equalizer (FBE), the logic
return equalizer (LRE), the serving ac equipment grounds (ACEG), the
integrated collector bar (ICB), and the serving dc-power plant battery return
reference (BRR) are connected to ground. The DMS SPG is usually one of
the following types of busbars: building principal ground (BPG), floor
ground bar (FGB), dedicated SPG bar, or a dedicated section of the serving
dc-power plant battery return (BR) bar. In non-ISG configurations, the
framework ground bus (rather than the FBE and LRE) is connected to the
DMS SPG.
floor ground bar (FGB):
A copper bar on each floor of a building provided for equipment grounding.
The FGB is connected to the VGR and effectively extends the BPG to each
floor level.
framework bonding bar (FBB):
A copper bar used for bonding a DMS-100 frame to the FBE. The metal
framework of each DMS frame is bonded to an FBB horizontally mounted
above the frame.
framework bonding equalizer (FBE) bar:
A copper plate mounted on insulators and used in an ISG DMS system to
bond DMS frames to ground. The FBE is preferably located close to
PDC-00 and the equipment frames, and has a single connection to the DMS
SPG. One Framework Bonding Bar (FBB) in each lineup is connected to
the FBE. No other conductors are connected to the FBE.
framework ground bus:
A copper plate mounted on insulators and used in a non-ISG DMS system
to provide ground reference to DMS frames. The framework ground bus is
preferably located close to PDC-00 and the equipment frames, and has a
single connection to the DMS SPG. It is the start and end point of a ground
loop formed with conductors that interconnect the FBB of all the PDCs in

Introduction 1–3
DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
the frame lineups. It is recommended that no other conductors are
connected to the framework ground bus.
ground:
A metallic connection, whether intentional or accidental, between an electric
circuit or equipment and the earth, or some conducting body that serves in
place of the earth. Typically, a ground is a connection to earth obtained by
a grounding electrode.
incidental ground:
An unplanned grounding connection.
isolated bonding network (IBN):
A bonding network that has a single point of connection to either the CBN
or another IBN.
isolated system grounding (ISG):
The DMS grounding arrangement in which the equipment logic returns are
connected to a plane that is separated internally from the framework ground.
DMS-100F systems configured without ISG have equipment logic returns
referenced internally to framework ground or battery return as required.
isolation:
The arrangement of parts of equipment, a system, or a facility to prevent
uncontrolled electrical contact within or between parts.
logic return bar (LRB):
An isolated copper busbar used in DMS ISG frame-based systems. An LRB
is installed parallel to the FBB. The first LRB of a DMS lineup is connected
to the LRE. Subsequent LRBs in the same lineup are daisy chained to the
first LRB. Each vertical logic return bar of an equipment row referenced to
the LRE is connected to an LRB. The DMS core is treated as a separate
equipment row with respect to the LRB. The LRB of the core is preferably
located above the IOE frame.
logic return equalizer (LRE) bar:
An isolated copper plate with a single connection to the DMS SPG.
Preferably, the LRE is located close to PDC-00 and the equipment frames.
The first LRB of each lineup is connected to the LRE. No other connections
are made to the LRE.

1–4 Introduction
297-1001-350 Standard 02.02 August 1997
single point ground (SPG):
A single connection used to reference equipment or a system to ground.
In an ideal IBN arrangement, no dc current flows through the single point
connection unless a fault condition exists.
vertical ground riser (VGR):
A continuous conductor extending ground potential throughout the height
of a multifloor building. The size of this conductor is either 750 kcmil or
is equal to or larger than the largest conductor used for power distribution
in the building. The FGBs on various floors are connected to the VGR.
vertical logic return bar:
A copper bar mounted vertically inside several types of DMS frames and
used to reference the logic return to the LRB.
1.2 Abbreviations and acronyms
The following list is provided as a reference for a quick identification of
abbreviations and acronyms used in this document.
ac: alternating current
BPG: building principal ground
BR: battery return
BRR: battery return reference
CBN: common bonding network
CEC: Canadian Electrical Code
CO: central office
CPDC: cabinetized power distribution center
CSA: Canadian Standards Association
dc: direct current
DMS: Digital Multiplex System
DMS SPG: DMS single point ground
FBB: framework bonding bar
FBE: framework bonding equalizer

Introduction 1–5
DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
FGB: floor ground bar
IBN: isolated bonding network
IGP: isolated ground plane
IGZ: isolated ground zone
ISG: isolated system ground
LR: logic return
LRB: logic return bar
LRE: logic return equalizer
LVD: low voltage disconnect
MGB: main ground bus (BCC terminology)
MGB: master ground bar (REA terminology)
NEC: National Electrical Code
NFPA: National Fire Protection Association
NTP: Northern Telecom publication
PDC: power distribution center
REA: Rural Electrification Administration
SPG: single point ground
TR: Technical Reference (Bell Communications Research)
UPS: uninterruptible power supply
VGR: vertical ground riser
VRLA: valve regulated lead acid

1–6 Introduction
297-1001-350 Standard 02.02 August 1997
1.3 Cross reference of terms
Table 1–1 is a quick cross-reference of terms used by Northern Telecom, the
BOCs, REA, and others.
Table 1–1
Cross reference of terms
NT BOC REA OTHERS
battery return (BR) –48 V return N/A – battery ground
– dc return
– positive discharge bus
– power return
building grounding
system CO GRD central office pro- tection grounding – COG – CO ground
building principal
ground (BPG) – OPGPB – PGP bus master ground bar (MGB) – COG – CO GRD bus
– facility ground
– OPGP
– principal ground point (PGP)
– reference point 0
– zero potential reference point
common bonding
network (CBN) integrated ground plane integrated ground zone – integrated ground system
DMS SPG main ground
bus (MGB) master ground bar (MGB) – main ground bar (MGB)
floor ground
bar (FGB) – CO GRD – CO ground bar
– CO ground bus
floor bar – COG
– COGB
– C.O. GRD
framework bonding
bar (FBB)
framework bonding
equalizer (FBE) bar –FG – framework ground
– framework ground bus
isolated bonding
network (IBN) isolated ground plane isolated ground zone (IGZ) –isolated ground system (IGS)
logic return (LR) – logic ground
– signal ground
logic return
bar (LRB) – logic ground
logic return
equalizer (LRE) – logic ground
vertical ground
riser (VGR) – vertical equalizer – vertical riser – C.O. ground riser – equipment ground riser
– GRD riser
– riser
– VERT EQLR

DMS-100 Family Power and Grounding Routine Maintenance Manual Applies to all BCS/PCL levels
2–1
2 Overview
The power distribution system supplies controlled and protected power to
DMS switch equipment. The grounding system provides hazard protection
for personnel and DMS equipment, and, within accepted standards,
immunity from operational and transient phenomena.
2.1 DC power
Power from a –48 V power plant is fed through dual primary battery feeders
(A feeders and B feeders) to the Power Distribution Centers (PDCs) of the
DMS equipment. Each feeder consists of a –48 V conductor and an
associated battery return (BR) conductor. The conductors of a feeder are of
equal cross section and are run closely together.
Power from a PDC is distributed to DMS cabinets or frames through
secondary battery feeders. Other required dc voltages, such as +5 V and
–5 V, are obtained from 48-V powered dc/dc converters located within the
DMS equipment shelves.
2.2 AC power
The ac-free version of the DMS switch is intended to maintain and enhance
the integrity of the IBN by obviating the need for bringing external ac power
to the switch. It provides internal inverters for feeding all ac powered loads
within the switch as well as the convenience outlets. Center-aisle lighting
provided with this version of the DMS switch is installed outside of the
switch IBN and fed from general purpose ac distribution panels.
An earlier version of the DMS switch uses integrated lighting and is
supplied with ac power from a general purpose distribution panel, an
isolation transformer, a standalone inverter, or a UPS.
2.3 Grounding
The ISG version of the DMS switch is a grounding arrangement in which
equipment logic returns are connected to a plane that is separated internally
from framework ground. The logic return of non-ISG DMS switches is
referenced internally to framework ground or battery return as required.
Within the overall IBN of the DMS switch, functional equipment blocks are
configured as individual single-point-grounded entities. A functional block

2–2 Overview
297-1001-350 Standard 02.02 August 1997
can be a shelf, frame, or a group of frames. Communication links between
functional blocks and to the outside world generally use ac coupling
techniques to ensure connectivity.