Appendix: Optional Internal Relays and RESET Button
MSA
ULTIMA X ® Series
GB
95
12.4 Fault Relay [Trouble]
[
Fig. 7 in chapter 3.4]
It is a normally-energised, single-pole, double throw [SPDT] relay. During normal
operation, the normally closed [NC] contacts are closed. When a fault is detected
or the power is disconnected the relay contacts will change as follows:
-
the normally closed contacts [NC] will open
-
the normally open contacts [NO] will close
and the relay switches to a fault condition.
The relay can remain STEADY ON or PULSED. These two different modes can
communicate different information to a PLC or DCS connected to the Fault Relay.
"STEADY ON" indicates:
-
The ULTIMA X
®
Series sensor is not correctly connected or
-
There is a fault in the ULTIMA X
®
Series Gas Monitor or
-
a relay has failed.
PULSED [once per minute] indicates:
-
The calibration of the ULTIMA X
®
Series Gas Monitor is invalid or
-
The CHECK CAL or CAL FAULT message appears on the ULTIMA X
®
Series
Gas Monitor.
12.5 Optional RESET Button
The optional RESET button is to allow latching relays to be reset at the Gas Monitor
location.
The RESET button must be a normally open type with a momentary contact when
pressed and have electrical ratings of at least 1 amp at 250 V AC.
Latching relays can be configured using the ULTIMA/ULTIMA X Series Controller.
In the "latching" configuration, when the RESET button is pressed, any latched
alarm will be reset providing the gas concentration that activated the alarm is below
the alarm set-point. In the "non- latching" configuration, the RESET button has no
effect on the alarms.
The RESET push button must be installed remotely and not directly into
the ULTIMA X cable gland entry. The switch must be fitted in an ap-
proved junction box and be ATEX approved for hazardous area use.
