Siemens SIPROTEC 6MD665, Manual, Page: 18 / 222

1 Introduction
4
6MD665 Manual
C53000-G1876-C103-3
Serial Interfaces A serial PC interface is provided for local communications with the device through a
personal computer using the operating program DIGSI
®
. This permits convenient
operation of all functions of the device.
A separate Service Port can be provided for remote communications via a modem, or
substation computer using DIGSI
®
4. This port is especially well suited for the fixed
wiring of the devices to the PC or operation via a modem.
Via the serial system interface all device data can be transferred to a central evalua-
tion unit or to a control center. This interface may be provided with various protocols
and physical transmission schemes to suit the particular application.
Communication with other SIPROTEC
®
4 devices which also have inter relay commu-
nication can occur via the serial interface to the (optional) on the device rear. Com-
munication is achieved regardless of the connection to the central device SICAM SAS
and a redundancy to the system interface.
A further interface is provided for the time synchronization of the internal clock via
external synchronization sources.
Further communication protocols can be realised via additional interface modules.
Process bus inter-
face The process bus interface allows a direct communication with SICAM HV modules. It
is equipped with an Ethernet module.
Power Supply The before-mentioned function elements and their voltage levels are supplied with
power by a power supplying unit (Uaux or PS). Voltage dips may occur if the voltage
supply system (substation battery) becomes short-circuited. Usually, they are bridged
by a capacitor (see also Technical Data).