5
The basic logic on which a High or Low Level Alarm is determined, is set out in the Table below:
If there is a Low Level Alarm, then the pump will be locked out until the alarm is manually reset. This lockout will only be
over ridden upon a High Level condition where both the Pump Start and High level inputs are closed.
Note that after a High level is triggered, the pump will run until the Pump Start and Stop inputs are opened.
is running, the Prime Loss input opens, for a continuous 2 minute period, a fault is immediately triggered and the pump
power down functions are as follows:
Input functions are as follows:
Input 2
Pump Stop
Open/Closed
Open/Closed
Open/Closed
Open/Closed
Open/Closed
Open/Closed
Open/Closed
Open/Closed
Input 1
Low Level
Closed
Closed
Closed
Closed
Open
Open
Open
Open
Input 3
Pump Start
Open
Closed
Closed
Open
Open
Closed
Open
Closed
Input 4
High Level
Open
Open
Closed
Closed
Open
Open
Closed
Closed
Pump
State
Off
On
Both On
Both On
Off
Off
Off
Both On
Alarm
-
-
High Level (after Timeout)
High Level (after Timeout)
-
Low Level
Low Level
High Level (after Timeout)
Input Function
Input 1 Prime Loss
Input 2 Pump Stop
Input 3 Pump Start
Input 4 High Level
Input
Function
Input 1 Prime Loss (BRIDGE IF NOT REQUIRED)
Input 2 Lead Pump Pressure Switch (set at say 350kPa)
not used
Input 3
Input 4 Low Pressure Switch (set at say 200kPa)
•
Pressure drops to 400kPA. Pump cuts in.
•
Pressure increases and Pump cuts out
•
Cycle continues
•
The controller has inbuilt timers for “Delayed” Start and Stop to obviate pump chatter. Upon Input 1 contact closure, the
pump will not start (delay start) for 1 second and will not stop (minimum run time) for 10 seconds (or 11 seconds from close
of Input contacts). This “run on” occurs even if Pressure switch contacts open during this initial period. If however run time
exceeds 11 seconds, the pump will stop immediately upon “open circuit” occurring.
•
If the Pressure Switch Input closes circuit as well as the Low Pressure Switch Input, a low pressure timer will begin counting.
If this condition exists for a period of 60 seconds, then both pumps are shut down and the system signals a level alarm. This
would be typical of a Loss of Prime or Burst Main situation
•
Pressure switches are normally closed and open on High pressure
Typical operation for Mode D:
