GAI-Tronics 495-001 User Manual

Pub. 42004-198D

GAI-TRONICS® CORPORATION

A HUBBELL COMPANY

Model 495-001 Mine Dial/Page

Phone Interface Cabinet

Confidential ity Notice

This manual is provided solely as an operational, installation, and maintenance guide and contains
sensitive business and technical information that is confidential and proprietary to GAI-Tronics.
GAI-Tronics retains all intellectual property and other rights in or to the information contained herein,
and such information may only be used in connection with the operation of your GAI-Tronics product or
system. This manual may not be disclosed in any form, in whole or in part, directly or indirectly, to any
third party.

General Information

The GAI-Tronics Mine Dial/Page Phone system provides the convenience of a telephone station plus
additional paging capabilities in gaseous or dusty locations too hazardous for standard telephone
equipment.

The system is used in conjunction with Touch Tone (DTMF) operated public telephone exchange or a
private branch exchange (PABX). Each station in the system is made up of two components: a 491
Series Mine Dial/Page Phone, and a Model 495-001 Mine Dial/Page Phone Interface Cabinet located
outside the hazardous area. The Model 495-001 Interface Cabinet is electrically connected between the
station and the telephone switchboard. Each station is connected to a separate line of the telephone
exchange. A simplified diagram for a Mine Dial/Page Phone system is shown in Figure 1.

A person at any properly installed GAI-Tronics 491 Series Mine Dial/Page Phone station can dial any
other such station or any other conventional telephone connected to that switchboard. If the switchboard
is tied into the public telephone system, calls can be made to, and received from any public telephone.

In keeping with MSHA regulations, at least one GAI-Tronics 491 Series Mine Dial/Page Phone station
for each interface cabinet must be installed on the outside of a coal mine.

Principles of Operation

Each 491 Series Mine Dial/Page Phone is normally connected by an individual pair of wires to the Model
495-001 Interface Cabinet, but up to five phones can be connected in parallel. (N
designed to operate with only one station off hook). Outgoing calls can be made from any station and
answered at any station - the same as when extension telephones are used. It is not possible to dial calls
between stations on the same line.

OTE: This system is

GAI-Tronics Corporation 400 E. Wyomissing Ave. Mohnton, PA 19540 USA

610-777-1374  800-492-1212  Fax: [phone]

V

ISIT WWW.GAI-TRONICS.COM FOR PRODUCT LITERATURE AND MANUALS

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Figure 1. Simplified System Diagram

Physical Description o f the Equipment

A GAI-Tronics Mine Dial/Page Phone system consists of one Model 495-001 Interface Cabinet plus as
many 491 Series Mine Dial/Page Phone stations as required. The 491 Series Mine Dial/Page Phone is
housed within corrosion-resistant, non-metallic enclosure. The handset rests in a combination cradle and
handle on top of the enclosure.

Each 491 Series station requires one Telephone Line Interface card, which measures approximately
13 × 10 × 7 inches (33 × 25.4 × 17.8 cm). The Model 495-001 Phone Interface Cabinet is 77 inches (1.96
m) high and has the capacity to support 80 stations. See Figure 2.

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Figure 2. Model 495-001 Telephone Interface Cabinet Outline

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The Model 495-001 Phone Interface Cabinet contains the following items:

Qty Part No. Description

8 10428-001 PCBA Rack Assembly (each holding ten Telephone Line Interface Assemblies)
1 10432-001 Power Supply/Metering Panel Assembly
1 10431-001 All-Call/Merge Assembly
1 10430-001 DC Power Transfer Assembly
1 10429-001 Housing for All-Call/Merge and DC Transfer Assemblies

Each PCBA Rack assembly occupies the space of a 5.25 × 19-inch rack panel and includes four terminal
blocks on the rear surface. The four terminal blocks include two marked DIAL/PAGE
connect ten pairs of wires from ten Mine Dial/Page Phones; and two marked T

ELEPHONE LINES to

PHONE LINES to

connect ten pairs of wires to the telephone switchboard. See Figure 3.

Figure 3. Wiring Diagram for 10428-001 Dial/Page Phone Interface Card Rack Assembly

The line number of a DIAL/PAGE

PHONE LINES is coordinated with the TELEPHONE LINES number and

the Interface Assembly position. Mine Phone Line 1 and Telephone Line 1 are both wired to the Interface
assembly plugged into slot 1. A fifth terminal block inside the PCBA Rack assembly is used to
interconnect multiple rack assemblies and to connect to the All-Call/Merge assembly.

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The All-Call/Merge assembly allows all-station paging in the normal dial access, or in the event of a
telephone switchboard failure, system-wide paging with push-button page switches on the 491 Series
Phone front panel. This assembly includes an audio amplifier and three relays, and is built on an 8-inch
square plug-in chassis plate. Refer to Figure 4.

Figure 4. All Call/Merge Assembly 10431-001

DC power to operate the interface circuitry ordinarily comes from an ac-operated power supply located
within the Power Supply/Metering Panel assembly. See Figure 8 and Figure 9. Space is provided within
this assembly for a rechargeable, non-liquid, lead acid 12 V battery. The battery backs up the system in
the event of power supply failure or ac power source failure. The Power Supply/Metering Panel assembly
contains meters and switches to indicate the state of the power supply and battery. The assembly
occupies the space of a 7 × 19-inch rack panel.

The battery charging circuit and power supply to battery switching system is packaged separately in the
DC Power Transfer assembly. This assembly is built similar to the All-Call/Merge assembly for service
by substitution and mounts within the housing. See Figure 10.

The housing for All-Call/Merge and DC Transfer assemblies occupies the space of a 10.5 × 19-inch rack
panel and houses the two assemblies described above. The housing includes four terminal blocks for
input/output connections. See Figure 7.

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Installation

Location of the Model 495-00 1 Interface Cabin et

The interface cabinet is not rated as “permissible” by MSHA regulations and should be located:

1. Outside the coal mine as close as possible to the point where the cable into the mine emerges from

underground (to avoid, or at least minimize, locating this cable out-of-doors).

2. As close as possible to the center of mine operations and/or point of personnel entry.

3. Within a weather-tight, but ventilated building with a reliable source of 120 V, 60 Hz, ac power (15 A

minimum).

In a mine-shaft installation, the interfac e cabine t idea ll y should set on top of the cable insta llat ion bore
hole. Typically, it is installed near the elevator shaft or entry slope. If possible, the Model 495-001
Interface Cabinet should be located at the site of the PABX telephone switchboard, but this is not
required. The interface cabinet includes a merge function so that if the PABX telephone switchboard or
the cable between it and the interface cabinet fails, the GAI-Tronics Mine Dial/Page Phone system
automatically switches to an all-stations-merged operation.

Cable and Lighting Requirements

Multiple conductor cable made up of No. AWG 19 twisted pairs with an overall electrostatic shield is
recommended to connect the interface cabinet to distribution points inside the coal mine. This cable is
typically available with 3 to 100 pairs. The larger sizes are used for the initial link from the interface
cabinet into the first main distribution point. The progressively smaller cables can be used for
intermediate and final distribution points.

The cable system for a typical 80-station system is shown in Figure 5. The drawing shows the use of 100,
50, 25, and 6-pair cable. Spare conductor pairs in all main distribution cables provide for future
expansion. Cable with an integral messenger wire, commonly called “figure 8 cable,” simplifies
installation.

Figure 5. Typical 80-Station Mine Dial Phone Cable System

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Single-pair cables can be used to connect each 491 Series Mine Dial/Page Phone to the nearest
distribution point. For distances up to one mile, unshielded twisted wire can be used. Shielded cable
should be used for longer distances and in situations where the cable is routed near ac power distribution
facilities, ac-to-dc rectifiers, or cables.

All underground cables should be installed in accordance with Federal requirements 30 CFR 75.516-2
and any applicable state requirements. The location o f station s at main portal s and working sec tion s
must be in accordance with Federal requirements 30 CFR 75.1600 and any applicable state
requirements.

If the mine cable (not in metal conduit) is exposed aboveground out-of-doors; adequate line-to-ground
transient protection, such as nominal 450 V carbon air-gap lightning arrestors, must be installed between
each conductor and ground.

The U.S. Code of Federal Regulations (30 CFR 75.521) requires arrestors within 100 feet of the
point a circuit enters a coal mine and that they be grounded separately from power system grounds.

Similarly, 30 CFR 77.508 requires arrestors on exposed wires ente ring bui ldings at the point of
entry.

Except where splices or connections are necessary outside the mine to meet this arrestor requirement, the
mine cable must run one continuous length from the point of connection to the interface cabinet. This
continuous cable run is a requirement for the system permissibility rating. The continuous cable is
necessary because transient line-to-line protection for the mine cable is provided within the interface
cabinet PCBA Rack Assembly between the pair of lines to each 491 Series Mine Dial/Page Phone. This
arrestor installation limits the coupling of transients that might appear across the pair of wires to each
phone.

P ABX Telephone Switchboard Requirements

The GAI-Tronics Mine Dial/Page Phone system uses a loop start DTMF (Dual Tone Multi Frequency)
line for each independent 491 Series Mine Dial/Page Phone station. In most situations, a Private
Automatic Branch Exchange (PABX) at the coal mine site best provides this function.

There are no special requirem ents for this PABX, and conv ention al te lepho nes at a bov eg round locat ions
can also be used with the PABX. This PABX can be provided by a public telephone company, leased or
purchased from an “interconnect” telephone equipment company.

The PABX should provide a standard two-wire loop-start 48 V dc analog line connection with
bridged ringing (17 to 67 Hz) for each Mine Dial/Page Phone extension. Three additional lines will
be required for Monitor and All-Call functions. Refer to Installation section under “Wiring
Telephone Interface Cabinet to Telephone System” on page 9 for detailed information.

We recommend that the PABX switchboard have standby batteries in the event of an ac power outage;
however, this is not a requirement. Lightning protection should be provided for the PABX per the
manufacturer’s recommendation.

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