Servomex SERVOTOUGH LaserExact 2950, Operator'S Manual

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SERVOTOUGH LaserExact Monitor, Operator Manual 02950001A_1
60 C
HAPTER
6
The WARNING relay deactivates when the SERVOTOUGH Monitor detects a
possible problem in the measurements, and the instrument measurements may
not be correct or accuracy of the measurements reduced. Examples of such cases
are low laser beam transmission due to dust on the optical windows or
misalignment, or incorrect values of the 4-20 mA PLC inputs for pressure and
temperature. A corresponding warning message will be displayed on the bottom
line of the LCD.
The ERROR relay deactivates immediately after the instrument has detected a
failure. Deactivation of the ERROR relay indicates that the instrument is not able
to measure the gas concentration. The error message will be displayed on the
LCD.
There are two options for the behaviour of the 4-20 mA PLC output in case of
deactivating of the ERROR relay.
Option 1:
Immediately after the ERROR relay has been deactivated the PLC holds the last
measured value for a time interval that is proportional to the instrument averaging
time. In the current software version the time interval is
T
⋅ =
3
τ
. After that the PLC
sets the output to 2mA as an error notification in addition to the ERROR relay.
Option 2:
The 4-20 mA PLC holds the last measured value for the gas concentration until
the ERROR relay is activated again. The PLC output is, thus, independent of the
errors, and the only error notification is the ERROR relay.
6.9 Configuring relay 3 output
Relay-3 can be configured in three ways by software as
1) Normal gas alarm
2) Inverted gas alarm
3) Maintenance
These three configurations are mutually exclusive. In addition the relay-3 function
can be inverted by hardware.
The different functions of relay-3 are selected by setting the parameter “Gas conc
alarm level” (see Section 4.3.6).
6.9.1 Normal configuration of relay-3, «Gas Alarm»
Alarm is signified when the measured gas concentration > abs (Gas conc alarm
level) for one or more of the measured gases. Normal configuration:
Alarm OFF = Relay-3 conducting (X)
Alarm ON = Relay-3 isolating (O).