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8 START-UP
Warning. When the apparatus is connected to its
supply, terminals may be live and the opening of covers
or removal of parts (except those to which access may
be gained by hand) is likely to expose live parts.
8.1 Instrument Start-Up
In normal operation, the range selector switch is set to
position 1 and the instrument displays the
– see Section 9.2. This is a general use page in which the
Page
alarm set points may viewed but not altered. To change an alarm
set point or program a parameter refer to Section 10. A 5-digit
Security Code is used to prevent unauthorized access to
programmable parameters. The value is preset at 00000 to allow
access during commissioning but should be altered to a unique
value, known only to authorized operators, as described in the
– see Section 10.3.
Setup Outputs Page
When all the required wiring connections and electrical checks
have been made correctly, switch on the power supplies to the
various units as follows:
1) Switch on the supply to the PSU.
2) Switch on the supply to the 6553 Display Unit.
8.2 Alarm Set Point
8.2.1 Type of Alarm Action
The alarm relay coil is energized during normal non-alarm relay
states and is de-energized upon recognition of an alarm
condition, thereby providing 'fail-safe' alarms. For example, with
Alarm 1 set point = 95.0%, when the display is indicating greater
than 95.0% (plus hysteresis), Alarm Relay 1 is energized and
Alarm 1 LED is OFF. When the display indicates less than 95.0%
(minus hysteresis), Alarm Relay 1 is de-energized and Alarm 1
LED is ON. This operating mode ensures that an alarm condition
is signalled in the event of a mains power failure. Repeat the
above procedure for Alarm Relay 2 set point = 90.0%.
8.2.2 Hydrogen Alarm Set Point
It is recommended that the hydrogen alarm set-points are
based on a reducing percentage of hydrogen as it is displaced
by air entering the application plant. This can be achieved by
setting Alarm 1 and Alarm 2 to give ample warning of the
development of a potentially explosive mixture. Factory settings
are Alarm 1 = 95.0% and Alarm 2 = 90.0%.
The procedure is as follows:
Access the programming pages (Section 10) and set the alarm
set points in accordance with the information in the
The hydrogen alarm set point can only be set with
Outputs Page.
the selector switch in position 1.
8.3 Electrical Calibration
The instrument is factory calibrated for electrical voltage signal
input. No adjustment is normally necessary for correct
functioning of the display unit. If electrical calibration is required,
a voltage source capable of supplying –250.00mV to 10.00 mV
is needed. Disconnect the katharometer input from the display
unit and the voltage source signal applied according to the
instructions in the
Range 1 Operating
Note. The 4689 instruments incorporate a two point
calibration sequence requiring both zero and span
inputs for a calibration. It is not possible to adjust either
the range zero or the range span scale points
independently.
Set Up
– see Section 10.
Electrical Calibration Page
23
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