Rel301/302 Inner Chassis; Unique Features; Fault Detection Software - ABB REL 301 Instruction Leaflet

I.L. 40-386.4
1.3.2

REL301/302 Inner Chassis

The inner chassis (Figure 1-5) consists of a frame, 2 switchjaws and the following modules.
Each module is identified by silk screen label.
• PT Module:
Consisting of 3 voltage transformers for V
• CT Module:
Consisting of 4 current transformers for IA, IB, IC and IP, where IP is used for zero-sequence
dual-polarizing ground current measurement.
• Filter Module:
Consisting of the anti-aliasing filters for the seven inputs from the vt and ct modules, the mul-
tiplexer to the A/D converter, the A/D converter itself, and the Opto-isolator for the input con-
tacts.
• Microprocessor Module:
Consisting of a microcontroller (16 bits Intel 80C196 at 10 MHz), two EPROM program mem-
ory chips; two RAM chips, an EEPROM for data retention, a real time clock with battery and
indication LED's.
• Power Supply (PWRSUP) Module:
This is an isolated switching power supply capable of supplying +5 Vdc for microcontroller
and surrounding IC logic, ±12 Vdc for reference voltages and + 24 Vdc for communication.
All output contacts are on this module.
Three power supply options are available:
48 Vdc
125 Vdc
250 Vdc
• Man Machine Interface (MMI)/display module (optional):
consisting of a 2-line, 16 character per line, liquid crystal display (LCD), four push-buttons for
setting data entries and a switch for either protection or reclosing information. If the MMI op-
tion is not supplied, the switch is supplied for resetting protection or reclosing LEDs from the
front panel.
• Reclosing/Synch-check Module (optional):
consisting of an independent microcontroller (16 bits Intel 80C196) with its IC logic, signals,
contact inputs and outputs.
1. 4.

UNIQUE FEATURES

1.4.1

Fault Detection Software

REL301/302 fault-detection software operates in two modes: Background and Fault mode.
The REL301/302 relay normally operates in the "Background mode". During non-fault operation
(Background mode), the REL301/302 Microprocessor checks hardware, services the man-ma-
chine interface including communication port(s), and checks for a disturbances in voltage or cur-
rent which indicates a potential fault. If a disturbance is seen, the program switches to the "Fault
mode", for several power cycles, to perform phase and ground unit checks for each zone and
logic functions.
The REL301/302 relay program functions are shown in a flow chart loop Figure 1-6, which the
Microprocessor repeats 8 times per power cycle. Most functions are performed all of the time,
in the background mode, as shown. An important detail (not shown in Figure 1-6) is that many
1-4
, V and V .
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