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Digital teleprotection terminal

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article image DM1200 – a stand alone product.

DEWAR Electronics manufactures the DM1200 Teleprotection terminal which is a stand-alone product utilising DSP technology. The terminal needs no add on equipment to ensure installation or set up.

By the simple change over of processor modules, the DM1200 offers G703, RS422 and V.F. teleprotection systems.

Set up and all terminal monitoring by the operator is achieved through a 4-line x 20 character LCD and keypad. Facilities, at no extra costs, also exist that allow for remote programming and supervision of the terminal via RS232/RS485LAN via a PC, laptop or modem.

Utilising non-volatile memory, time stamping allows history of events to be recorded. Three levels of pass code access allow for set up, test and maintenance to ensure added terminal security. A flashing LCD display evidences events at the terminal.

To safeguard against single component failure the DM1200 also features full complimentary dual path hardware and firmware redundancy from signal input to signal output.

The terminal itself has no internal cabling or potentiometers. All cards are keyed and interface to a motherboard and lock securely in place. Use of microprocessors and DSPs ensure minimum component count with a resultant long MTBF.

Removal of a module is achieved by the simple removal of the front panel, releasing the module clip and then sliding the module free.

G703: The DM1200 G703 teleprotection system interfaces up to four trip inputs and outputs to CCITT G703 64 KB digital bearer.

RS422: The DM1200 RS422 teleprotection system interfaces up to four trip inputs and outputs to RS449 or RS530 from 9 KB to 80 KB through a digital communications channel.

Voice frequency: The DM1200VF teleprotection (analogue tones) system can interface one command (utilising two FSK channels) or two commands (each utilising a single FSK channel) for blocking, permissive underreach/overreach and intertripping applications. Frequencies can be set from 300Hz to 4095Hz in 1Hz steps, with FSK shifts from 20Hz to 500Hz in 1Hz steps.

A high speed Loss of Guard (LoG) for loss of channel or "through arc" tripping capability is standard on VF (tones)for use with PLC links and other communication channels.

The 19", 3U high terminal houses circuit cards and the Monitor module that comprise the DEWAR DM1200 terminal All wiring is to the rear terminals which are fitted with supplied mating connectors. This allows pre-wiring prior to actual installation of the terminal.

This simplifies both installation and maintenance. A two level back plane arrangement separates the functions of field connections and internal signals thus protecting the equipment from accidental damage and interference.

All active components are mounted on keyed circuit cards that are accessible from the front of the terminal.

Reversible mounting brackets provide for either flush mounting in the user's rack or where depth is restricted, semi projection mounting. Provision is made for the user to fit a 'Tally Plate' to the top of the terminal.

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