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PRESYS
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Instruments
Whenever configured for current and voltage, the control outputs 1 and 2
should have their limits specified by the Lim Low and Lim High parameters. Note that
Lim Low and Lim High are expressed as a percentage of output full scale and that
the output signal saturates at those points. For example, in order to have an output
under a current of 4 to 20mA, we should assign 20.0% for Lim Low and 100.0% for
Lim High.
Whenever configured for relay, the control outputs 1 and 2 should have a
specified cycle period.
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 setpoint (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 setpoint
determining the lower and higher points where the deviation alarms occur. The alarm
relays are only enabled after the user has selected the setpoint 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)
DCY - 2057 Pressure Controller
Delay
NO ALARM
Fig.18 - Relay with delay
Time
Delay
ALARM
Operation
Page 32
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