envea STACK 602, Руководство пользователя

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9 Maintenance STACK 602
46
(PC-000848-MA Issue 5, December 2021)
ENVEA UK Ltd
8.2 Opacity Self-Tests
8.2.1 Viewing Opacity Self-Tests
1. Open the QA/Self-Tests menu screen, then select Device | Stack n
Opacity to display the self-test results for a sensor (see
Figure 22
below):
1a. Light Normal : displays the current level of scintillation at the Receiver.
This should be the same as the light level set up initially on the Set-Up
screen. A typical value is between 50 and 100 (see section
0
on page
42
).
Figure 22: Opacity sensor test results (alternating).
1b. Comms Check : verifies the control unit is reading opacity values
correctly from the sensor.
1c. Opacity Light Off (ZERO) check : this check turns the Transmitter
brightness down to zero and checks the scintillation also drops close to
zero.
Example: the results show a Light Normal scintillation count of 80.51
just before the test, which is reduced to 0.2 (0%) during the test. The
display now alternates between showing PASS and the numerical result.
1d. Opacity Light 50% (SPAN) check : the aim of this test is to simulate
an opacity reading electronically by oscillating the Transmitter brightness
between 100% and 50% (its original setup level) at a frequency within
the measurement band of the instrument. An expected reading from this
test is around 200,000.
Example: the results show the Light Normal level of 80.51 before the
test reduced to 39.3 (49%) during the test. The display now alternates
between showing PASS and the numerical result. However, if the result
is significantly different from 50%, the instrument generates an Opacity
Span alarm (see note below).
2. Repeat the procedure for additional sensors as required.
NOTE
: If an Opacity self-test is outside tolerance levels or generates an alarm, refer to
the troubleshooting section 9.5.7 on page 54 .