Hach Sigma 950, Инструкция по эксплуатации инструмента

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90
Programming Features
B.9 Advanced Options
2. From the Main Menu, select
OPTIONS > ADVANCED OPTIONS.
3. Use the up and down arrow soft keys to highlight the choice, then press the
SELECT
soft key to pick that item.
4. Proceed through the series of screens to configure the parameters for the selected
item.
Advanced Options include the following:
B.10 Alarms
Setting the Deadband
After entering the trip point, enter a “deadband” value. The deadband is the area between
alarm “turn on” and “turn off.”
Note: Rainfall and Flow Rate of Change alarms are High Set Point conditions; they take no
deadband, and they are time dependent.
The purpose of setting a deadband is to eliminate alarm relay chatter which may occur if
the turn-on and turn-off values are too close together. Small fluctuations that occur when
the reading is at or near the trip point can toggle an alarm relay on and off very rapidly.
Note: ou must log rainfall to use an alarm on a rainfall condition; likewise, you must log flow in order
to implement an alarm on a flow rate of change. If you forget, you are reminded when the program
begins.
In the pH example ( Figure 27 ), the deadband is set to 0.10 pH. When the pH reached 6.9
(lower dashed line), the alarm tripped, but the alarm did not turn off until the pH came
back up to 7.00. This difference is the deadband setting which should be set to the
characteristics of each measured item.
Four alarm relays are provided with SPDT (Form C) contacts. The normally open,
normally closed, and common contacts are on the terminal wiring board.
Multiple alarms can be enabled one at a time. Multiple alarms can be assigned to
individual trouble conditions, to individual relays, or assigned to all the same relay.
• 4–20 mA Outputs ( section 8.3.1 on page 64 )
• Alarms ( section 8.4 on page 68 )
• Calibration
• Flow Totalizer ( Flow Totalizer on page 95 )
• Diagnostics ( Diagnostics on page 93 )
• Data Log ( Data Log on page 91 )
• Storm Water ( Stormwater on page 98 )
• Set Point Sampling ( Set Point Sampling on page 97 )
• Languages (English, Czech, Danish, French, German, Italian,
Portuguese, Swedish, Dutch, and Spanish. (The 950 supports English
and one other selected language).