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 both Pumps 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 pumps will both run until the Pump Start and Stop inputs are opened
Mode C: Standard Configuration plus Prime Loss
Mode D: Pressure Pumping Configuration
Typical Operation Mode D:
As per Mode A, except Input 1 is connected to a prime loss/flow switch. If at any stage, after Pump Start, or whilst a
pump is running, the Prime Loss input opens, for a continuous 2 minute period, a fault is immediately triggered for that
pump and duty alternates. Input functions are as follows:
Duty Pump:
Lead Pump
Standby Pump:
Lag Pump
Input functions are as follows:
•
Pressure drops to 400kPa: Lead (for this cycle) Pump cuts in.
•
Pressure increases and Pump cuts out.
•
Cycle continues with duty (Lead and Lag) alternating between the two pumps.
•
If pressure continues to drop to 350kPa, the Lag Pump will cut in and remain running until Lead Pressure
Switch opens circuit. Then duty alternates.
•
No faults are logged against the Lead Pump if the Lag Pump starts.
•
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 Lead Pressure switch opens circuit
during this initial period. If however run time exceeds 11 seconds, the pump will stop immediately upon “Open
Circuit” occurring.
•
If the Lead Pressure Switch input closes circuit as well as he Low Pressure Switch input, both pumps will be
turned on and the 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 Opened on High Pressure.
•
Prime Loss functions as per mode Mode C.
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 400kPa)
Input 3
Lag Pump Pressure Switch (set at say 350kPa)
Input 4
Low Pressure Switch (set at say 200kPa)
Input 1
Input 2
Input 3
Input 4
Pump
State
Alarm
Low Level
Pump Stop
Pump Start
High Level
Closed
Open/Closed
Open
Open
Off
-
Closed
Open/Closed
Closed
Open
On
-
Closed
Open/Closed
Closed
Closed
Both On
High Level (after Timeout)
Closed
Open/Closed
Open
Closed
Both On
High Level (after Timeout)
Open
Open/Closed
Open
Open
Off
-
Open
Open/Closed
Closed
Open
Off
Low Level
Open
Open/Closed
Open
Closed
Off
Low Level
Open
Open/Closed
Closed
Closed
Both On
High Level (after Timeout)
