GE P741, Technical Manual

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SCADA Communications P74x/EN SC/Na7
MiCOM P741, P742, P743 (SC) 13-3
SC
1. SCADA COMMUNICATIONS
1.1 Introduction
This section outlines the remote communications interfaces of the relay. The relay supports
a choice of one of five protocols via the Rear Port 1 communication interface, selected via
the model number when ordering. This is in addition to the Front Port and the optional Rear
Port 2, which supports the Courier protocol only, and the optional Ethernet port.
Rear Port 1 is an EIA(RS)485 interface and is isolated and is suitable for permanent
connection whichever protocol is selected. The advantage of this type of connection is that
up to 32 relays can be ‘daisy chained’ together using a simple screened twisted pair
electrical connection. Refer to section 1.2 for further information.
Rear Port 2 is menu-selectable as either EIA(RS)232 or EIA(RS)485 or K-Bus. Refer to
section 1.3 for further information.
The Ethernet port supports IEC 61850-8-1. Refer to section 3 for further information.
It should be noted that the descriptions contained within this section do not aim to fully detail
the protocol itself. The relevant documentation for the protocol should be referred to for this
information. This section serves to describe the specific implementation of the protocol in
the relay.
1.1.1 Read only mode (Command Blocking)
A Read Only mode is available for the rear communication ports of the Px40 relays. When
Read Only mode is enabled for a port, all setting changes and most commands/control
actions are blocked (not accepted by the relay). The full functionality is described below. It is
similar to the ‘Command Blocking’ setting of Px30 relays.
Read Only mode can be enabled/disabled for the following rear ports:
•
Rear Port 1 – IEC 60870-5-103 and Courier protocols
•
Rear Port 2 (if fitted) – Courier protocol
•
Ethernet Port (if fitted) – Courier protocol (“tunnelled”)
Read Only mode is not currently required for IEC 61850, as there are no settings or controls
implemented.
Read Only mode does not apply to the Front Port, that is intended for local connection only.
The following settings enable and disable the Read Only Mode:
•
[09FB: CONFIGURATION, RP1 Read Only]
•
[09FC: CONFIGURATION, RP2 Read Only]
•
[09FD: CONFIGURATION, NIC Read Only]
Read Only mode can only be disabled from either the front panel User Interface or via the
Front Port.
Read Only mode can be enabled/disabled in the PSL by using the DDB signals ‘RP1 Read
Only’, ‘RP2 Read Only’, ‘NIC Read Only’.
When Read Only mode is enabled, the commands that are blocked (not accepted by the
relay) and the commands that are allowed (accepted by the relay) are as follows.
(1) IEC 60870-5-103 protocol
Blocked:
INF16 auto-recloser on/off (ASDU20)
INF17 teleprotection on/off (ASDU20)
INF18 protection on/off (ASDU20)
INF19 LED reset (ASDU20)
private INFs e.g CB open/close, Control Inputs (ASDU20)