YOKOGAWA av550g, Руководство пользователя

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< 10. Other Functions >
10-21
IM 11M12D01-01E
10.5.3 Setting Blow back Start Time
When mode is set to [Semi-auto]:
Hold time and blow back time should be set.
Hold time is the time required from the end of blow back to the restart of measurement. Set the time
so that a sample gas that flows through the sensor after blow back can displace the blow back gas
in the sensor and thus the output returns to normal. Setting range is from 00 minute 00 second to 60
minutes 59 seconds. Once the blow back starts on a channel, its individual analog output is held at a
value preset in the Output hold setup and excluded from averaging group calculations until the preset
output hold time has elapsed.
Blow back time is the time for blow back in one channel. Setting range is from 00 minute 00 second to
60 minutes 59 seconds. A timing chart showing blow back time hold time, analog output status, and
blow back gas switching solenoid contact action timing is provided in Figure 10.26.
When mode is set to [Auto]:
In addition to the above hold time and blow back time, interval, start date, and start time should be set.
The interval between blow back cycles can be set in the range 000 day 00 hour to 255 days 24 hours.
Once blow back is started, it is performed for all installed channels. Thus blow back interval must be
longer than the sum of blow back time and hold time for all channels.
Start date and start time specify the day and time that auto blow back is first performed.
To set June 21, 2004 at 1:30 pm, set Start date to 21/06/04 and Start time to 13:00.
<Setting procedure>
When the blow back mode is set to [Semi-auto] on the [Blow back setup] display:
[Hold time] and [Blow back time] items appear. Select [Hold time] and then touch the Enter key. A
numerical data entry display will appear. Enter the desired value and touch the Enter key. In the same
manner, set the Blow back time.
When the blow back mode is set to [Auto] on the [Blow back setup] display:
In addition to [Hold time] and [Blow back time] items, [Interval], [Start date], and [Start time] items
appear. Enter the desired values for each item in the same manner as above.
NOTE
Observe the following cautions when setting the blow back timing.
1) When blow back is to be started by a contact input signal, you need to set the relevant contact
input signal to Blow back start on the [Input contacts] display.
2) Blow back may be delayed or cancelled by status of the affected channel of by the status of other
channels, as explained by Table 10.5.
3) If the (Blow back) Interval setting is shorter than the sum of blow back times plus hold times for
all channels, then the system will be in blow back status when the second auto blow back cycle
attempts to start. In this case, the second auto blow back will be cancelled.
4) If the (blow back) interval is set to 000 day 00 hour, then auto blow back will not be performed.
5) If you set the start date before the current date, then auto blow back will not start.