wtw Turb 2000 Series, Operating Manual

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Instrument configuration (CONFIG mode) Turb 2000 Series
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6.5 Configuring the alarms
To connect the relay, see section 2.3.4. Two relays are provided that are designed to operate as two
independent programmable alarms. Three types of information must be input to fully program each
alarm:
1. The alarm function (HI, LO, OFF or Error)
2. The alarm set point (level at which the alarm activates)
3. The delay time for the alarm (the time that the set point must be exceeded prior to alarm activation
and the time before resetting the alarm)
These three items are described below:
Alarm function: The alarms can either be turned OFF or programmed to operate in one of two different
manners:
•
HI alarm: the relay changes state when the measured turbidity level is higher than the programmed
alarm level for a prescribed amount of time.
•
LO alarm: the relay changes state when the measured turbidity level is lower than the programmed
alarm level for a prescribed amount of time.
•
Error: the relay changes state when a system error occurs. If a system error occurs a message will
appear on the lower row of the screen describing the problem.
Note
The relays automatically change state when an internal system failure is detected.
Alarm set point: The level at which an alarm activates is called the alarm set point. On the instrument,
the alarm set point is designated as “S/P”. The set point is adjustable to any valid turbidity level over the
range of the instrument in steps of 0.01 NTU.
Alarm delay time: The alarm delay times are used to prevent ringing of the alarm when the measured
turbidity level is close to the set point. The function of the delay times is as follows:
Delay on :
The turbidity level must exceed the alarm set point continuously for at least this
number of seconds before the alarm activates.
If the delay on time is set at 5 seconds and the process turbidity exceeds the set point
continuously for only 4 seconds, the alarm will not be activated. However, process
turbidity exceeds the set point continuously for 5 seconds or more, the instrument will
activate the alarm.
Delay off :
The turbidity level must not exceed the alarm set point continuously for at least this
number of seconds prior to deactivation of the alarm.
If the delay off time is set to 5 seconds and the process has exited out of the alarm
condition, the alarm will be reset only if the process is out of the alarm condition for a
continuous 5 seconds. Otherwise, the instrument will still signal an alarm condition.