Service Settings For Transceiver 21-219; Earthing - Hitachi 670 Series Application Manual

1MRK505382-UEN Rev. K

5.6.6.2

Service settings for transceiver 21–219

Only one setting is required for transceiver 21–219. It has to be set to internal or external clock

depending on the configuration of the telecommunication network. Clock synchronization

configuration using the rotary switch can be done on the fly.

When transceiver 21-219 port is synchronized from the SDH master clock (transceiver acting as

slave), transceivers at both ends of the line are configured to use an external clock. To achieve this,

the rotary switch on the transceiver's front panel is set to point to position 0 (LEDs 1, 2, 4 and 8 are

not lit).

When the PDH/SDH is port synchronized from transceiver 21-219 (transceiver acting as master), the

local end transceiver is configured to use the internal clock. To achieve this, the rotary switch on the

transceiver's front panel is set to point to position 1 (LED 1 is lit and LEDs 2, 4 and 8 are not lit).

5.6.7

The interface protection circuitry in transceiver 21-219 requires that the SDH multiplexer (SDH MUX)

interface is either directly or via low resistance connected to the same earth as the earthing screw on

the transceiver's front panel. There is no overturned protection in transceiver 21-219. If there is

potential difference between transceiver 21-219 earth and SDH MUX earth, current can flow in the

outer shield of the connecting cable. This may damage the cable and degrade the system

functionality resulting in bit errors.

The outer shields of the coaxial cables must be earthed to the chassis via the BNC contacts at both

ends as shown in Figure 87.

Transceiver

IEC07000158 V1 EN-US

Figure 87:

Communication set-up, 670/650 series

Application Guide

BNC contacts with the

screen connected directly to

TX

21-219

RX

Coaxial cables

Make sure the boxes are

Earthing

properly earthed with shortest

screw on

possible connections to, for

front

example, an earthed frame

Important: power supply

from the same battery

Earthing principles

© 2017 - 2023 Hitachi Energy. All rights reserved

< 10 m

chassis (earth)

Communication set-up

GUID-F8C098BE-407F-4281-951C-BE4AB476C2AA v1

GUID-3321FABA-BC02-4367-BE8F-92C2D37796E5 v1

RX

SDH

MUX

TX

IEC07000158-1-en.vsdx

Section 5

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