Hardware Description; Mechanical Construction; Box Construction; Electrical Connections - GE DFF1000 Series Instructions Manual

Digital frequency relay

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Table Of Contents

Table of Contents

6. 6. 6. 6.

The DFF incorporates electronic components that might be affected by electrostatic discharge currents

flowing through certain component terminals. The main source of electrostatic discharges is human

body, specially under low humidity conditions with carpet floors or isolating shoes. If such conditions

are present special care should be taken while manipulating DFF´s modules and boards. Operators,

before even touching any component, must make sure that their bodies are not charged by either

touching a grounded surface or by using an antistatic grounded wrist bracelet.

6.1 MECHANICAL CONSTRUCTION

The DFF box is a standard 19" rack four units high, manufactured in stainless steel and painted with grey epoxi

resin. It is composed of a backbone structure, that includes the strips where all the modules and boards are

connected, plus a rear plate with all the female connectors.

All the boxes have a surge ground connection terminal, essential not only in terms of safety but also on behaviour

against electromagnetic interference.

All the modules are of the drawout type, enabling easy maintenance and repair of the equipment.

The DFF also incorporates a plastic antitampering front cover. This cover keeps the relay sealed and provides a

high protection against dust and water (IP51 index according IEC 529). The use of a push-button allows access to

the main functions without the need of removing the cover.

The front and rear views of the DFF are shown on figures 5 and 6.

All the DFF electrical connections (voltage inputs and digital I/Os) are done through drawout terminal boards of 12

terminal blocks each located at the rear of the device.

Additionally to those terminal blocks, the DFF includes two communication ports. One front DB-9 port for local

connection and another located on the rear nameplate, used for remote connection to the PC.

This second port may be used for point-to-point connection with a central computer in the substation by means of

a multiplexer.

This second communication port may be, depending on the selected option, a RS232 with a DB-9 connector, a

fiber optics (glass or plastic) connector or finally an RS-485.

In the rear plate are also included the terminal blocks for the time synchronization through a demodulated IRIG-B

input.

The internal architecture of the DFF1000 is composed of the following 4 units high drawout modules:

- 1 Module for the power supply.

- 1 Magnetic module (Analog inputs).

- 1 Module for the protection CPU.

- 1 Module for the communications CPU.

- 2 Modules for the digital Inputs and Outputs.

- 1 Module for extra digital Outputs.

NOTE: Models DFF1001 and DFF1002 provide a smaller number of I/O modules.

GEK – 106166B