Display Test; Selecting Primary Values; Optically Isolated Serial Communication Port - ABB REX 521 Operator's Manual

REX 521
3.1.6.
3.1.7.
3.1.8.
14
Protection Relay
Operator's Manual
Increase
E
Push and
Decrease
Fig. 3.1.5.-1 Adjusting display contrast
• The display contrast may be adjusted anywhere in the menu structure except in
the setting menus where the [E] button is used for entering the setting mode.
• The selected contrast value is stored in a non-volatile memory and thus, after an
auxiliary power failure, the contrast is restored automatically.

Display test

Upon auxiliary voltage connection, the backlight is turned on and a short display test
is run. This display test includes all the LEDs and the LCD. The LEDs are tested by
turning them on simultaneously while the LCD shows two patterns so that all the
pixels are activated. After the test, the display returns to normal state.
• The display test can also be started manually by navigating to
Configuration\Display\Test display and then selecting
Test display (refer to section "Menu chart" on page 15).

Selecting primary values

The setting values, input data and recorded values that are relative to some quantity
can be obtained directly in amperes and volts. For the relay to know how to convert
between primary and per unit values, the setting values describing the measurement
devices (CT, VT, VD, RS) need to be properly set.
1. Navigate to Configuration\Display\Primary values and select
Primary values instead of the default Per unit values.
2. Navigate to Configuration\Meas. devices and enter the data for all
the CTs and VTs, VDs and RSs that are in use in that particular hardware. For
information about setting the rated values for the protected unit and about the
technical data of the measuring devices, refer to
General (see "Related documents" on page 6).

Optically isolated serial communication port

The front panel of the protection relay is provided with an optical serial
communication connector. The connector is used for programming the relay with a
PC via a RS-232 cable, type 1MKC950001-1.
1MRS 751107-MUM
Technical Reference Manual,