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PRESYS
| Instruments
3.2.4 - Level 4 - Alarms
In level 4 the outputs 2, 3 and 4 may be configured as alarm outputs; in this case,
they are hence called relay 2, relay 3 and relay 4, respectively (see figure 19). A
maximum of three alarm relays may be available through the acquisition of the
corresponding option modules. The possible types of output for relay 2 are: SPST relay,
open collector voltage or solid-state relay. In the case of relays 3 and 4 the available
types of output are: SPDT relay, open collector voltage or solid-state relay.
Each relay may be associated to the set-point (SP) and the hysteresis (HYST) of
only one type of alarm. There are six possible types of alarm: low for channel 1 (CH1L),
high for channel 1 (CH1H), deviation for channel 1 (CH1D), low for channel 2 (CH2L),
high for channel 2 (CH2H) and deviation for channel 2 (CH2D).In the case of the
deviation alarm, (SP) denotes the span above and below the local set-point determining
the lower and higher points where the deviation alarms occur. The alarm relays are only
enabled after the user has selected the set-point values and pressed the ENTER key.
DELAY - it causes the alarm operation of each relay to be delayed by a user
defined period of time (DELAY). Figure 18 below, illustrates the delay for a high alarm.
Measured Variable
High alarm
set - point
(1Hr3)
SAFE - provides relay safety. Relay safety condition means that relay coils are
energized when the instrument is powered and are de-energized under an alarm
condition or in the event of a power failure.
Delay
NO ALARM
Fig.18 - Relay with delay
DCY-2050 and DCY-2051
Time
Delay
ALARM
Operation
Page 31
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