6. Control Functions and Parameter Settings
6-50
1) Multipump control operation
An example of actual operation for the multipump control is shown below.
O N
O N
O N
T3
O N
(1 )
(2 )
(3 )
(4 )
tim e
(5 )
T1
T1
T1
U LT
L LT
P ID O utpu t
Sequ
en
c
e
O
u
tp
u
t
P S O 1
(p um p 1)
P S O 2
(p um p 2)
P S O 3
(p um p 3)
P S O 4
(p um p 4)
P S O 5
(p um p 5)
T2
ULT:
PID output upper limit value in VAT2000
LLT:
PID output lower limit value in VAT2000
T1:
Holding time
T2:
Continuous operation time limit
T3: Changeover
time
The ON/OFF control of multiple pumps is carried out so that the operation time of each
pump is equal.
(1) When the PID output reaches ULT for a time T1, the pump 2 with the shortest
operation time turns ON (through PSO2 output).
(2) When the PID output reaches LLT for a time T1, the pump 1 (PSO1), with the longest
operation time turns OFF.
(3) Following (2), when the PID output still hold at LLT for a time T1, the pump 3 (PSO3)
with the longest operation time turns OFF.
(4) ON/OFF pumps changeover is ignored If the PID reaches LLT or ULT for a shorter
time than T1
(5) If the time that the pump’s ON/OFF control is carried out reaches T2, the pump 4
(PS04) with the longest operation time will turn OFF, and the pump 5 (PSO5) with the
shortest operation time will turn ON after T3.
