MSA 9020 SIL - Page 16

15
Description
GB
Model 9010/9020 SIL
A) Input Signal is Over 103 % FS
* Can be acknowledged by operator pressing UP or DOWN key
B) Input Signal Returns Back to Measuring Range Interval
* Can be acknowledged by operator pressing UP or DOWN key
The CAUTION set-point, which threshold can be set to100 % of full scale, can be used for the
remote OVERRANGE indication.
WARNING!
In case of an OVERRANGE signal, it is necessary to check that the area around a detector on site
is free from dangerous gas concentration for the specific channel before an alarm reset is
performed.
Failure Conditions
Besides the red alarm LEDs, the control units are equipped with a yellow LED (FAILURE) which
signals possible failures of control unit functions (individual for each channel when using a Control
Unit 9020 SIL).The remote indication is accomplished via a related relay (FAILURE), which is
equipped with two free voltage contacts connected in series to guarantee reliability of switching
function.The failure type is shown on the display, a list can be found in chapter 8.1.
SYSTEM failure condition is monitored by an internal watchdog and in case of any system
malfunction the SYSTEM failure LED and the Failure relay are activated.
Analogue output status in failure conditions follows a setting made in Access Code 4 P20.
Non ATEX mode ATEX Mode
Display "EEEE "EEEE"
C,W,A *Activated *Activated
FAILURE Activated Activated
HORN *Activated *Activated
4-20 mA Output As it is configured in Access Code 4, P20 22 mA
Non ATEX mode ATEX Mode
Display
"EEEE"alternates
with actual measured value
"EEEE" stays displayed
until it is acknowledged manually
C,W,A
*Activated
stays activated until it is reset
manually
*Activated
stays activated until it is reset
manually
FAILURE In normal state
Activated
stays activated until it is reset
manually
HORN
*Activated
stays activated until it is reset
manually
*Activated
stays activated until it is reset
manually
4-20 mA Output Follows the input change
stays at 22 mA until it is reset
manually
In the ATEX mode, the Failure relay coil is normally energized.
With Control Unit 9020 SIL, the failure is indicated once for both channels if output relays
are used.