Alarm relay off timers
The 8 relays on the PCB are allowed to take time to de-energise.
For example, this delay could be used to keep fans running for a longer period after the
gas alarm to allow a larger area to be vented.
ENGINEER’S menu 24 allows each of the 8 relays to be selected by using the UP (1)
and DOWN (5) buttons and then for each relay use the + (4) and – (2) buttons to change
the time for delay in increments of 1 second. The minimum time is 1 second.
Additionally, the first 16 external relays can also have a time delay to de-energise which
has been output by an event or pattern.
Pressing SELECT (3) will save the delay times in non volatile memory and return to the
ENGINEER’S menu.
Voting relays
(Note: 4 of these relays are also used with time weighted alarms)
ENGINEERING menu 25 allows channels to be assigned to a group voting system.
8 relays on the main PCB will be activated according to the voting set up, and de-
activated when the condition has subsided and after the relay off timer has expired.
Using UP (1) and DOWN (5) to select the group, then use the + (4) and – (2) to select
how many alarms have to be active in this group to cause a relay to activate.
E.g. group 2 may have 5 sensors in its group and 3 alarms are required to activate relay
called High (G2).
On entering menu 25, the direct 4-20 channels are displayed. UP (1) and DOWN (5)
buttons will display which groups this channel is in whilst the + (4) and – (2) buttons
change the channel being viewed. If a channel was in groups 1 and 3 then the display
would be 1-3-----. If it was in groups 2, 3 and 7 then the display would be -23---7-.
Pressing UP (1) or DOWN (5) changes this selection so keep pressing until the correct
grouping for your application appears. Any channel can be in all groups and this would be
displayed as 12345678.
Pressing SELECT (3) presents the Addressable channels for a repeat of the above.
Groups can contain a mix of sensors from 4-20 direct or Addressable channels.
Time weighted alarms
(Note: This applies to OPT5,6,7,8 relays)
Two types of time weighted alarms can be set using menu 31. STEL is a short time
exposure level which is a weighted average of gas level for the last 15 minutes. It is
associated with one of the four groups (5,6,7,8) of sensors. Each group may have any
number of sensors within it and whichever is the highest reading in the group, this
reading is used to formulate the value of STEL.
LTEL is a long time exposure level taken over 8 hours and calculated in the same way as
STEL. Both STEL and LTEL have individual alarm settings but both act upon the same
relay. These alarms are rising only. Each gas must clearly be of the same type. If STEL
or LTEL alarm level is set to a value greater than zero, then this voting group becomes a
TWA (Time Weighted Average) group and the normal voting function is suppressed.
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