Technical data

1MRS751108-MUM

REX 521

Protection Relay

Technical Reference Manual, General

5.1.14. Display panel (HMI)

The front panel of the relay includes:

• A 6 x 16 character LCD

• Three protection indication LEDs

• Eight alarm LEDs

• Arrow buttons for menu navigation

• Optically isolated serial communication port

Additional features of the display:

• Contrast adjustment with temperature compensation

• Backlight control

5.1.15. Indication LEDs

The relay is provided with three indication LEDs (green, yellow and red). With

latching/non-latching, steady/blinking light the LEDs indicate different states and

operations of the relay. For more information, see Operator’s Manual.

5.1.16. Alarm LEDs

The relay is provided with eight alarm LED indicators (red). With latching/non-

latching or steady/blinking light the alarm LEDs indicate different states and

operations of the relay. The user can freely enable and disable the predefined alarms.

By default, all the alarms are disabled. To enable alarms, do the following:

1. Select a mode (Control\ALARM#\Control setting\Object mode) for function

blocks MMIALAR1-8 (these are uninitialized by default). The mode you

selected affects the behaviour of the alarms coming to a certain LED.

MMIALAR1 affects LED1, MMIALAR2 affects LED2, and so on. Three alarm

modes are supported regarding latching: non-latched, latched with steady LED,

and latched with blinking LED. For more information about MMIALAR

function blocks, see Technical Reference Manual, Standard Configurations

(“Related documents” on page 10).

2. Enable the alarms by setting the bitmask for the LED

(Configuration\Alarm LEDs\LED1, LED2...)

The alarms can be acknowledged (cleared) from the main view by pressing the [C]

button for 2 s. This acknowledges all the alarms.

For a certain MMIALAR function block, the alarms can also be acknowledged by

selecting “Acknowledge” for parameter Alarm ack

(

Control\ALARM#\Control setting\Alarm ack). This acknowledges

alarm(s) only for the corresponding LEDs. After the acknowledgement, the status of

a certain LED (off/steady/blinking) depends on the selected mode and whether the

alarm is still active or not.