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be determined from the pump curve and system curve intersection. One
assumption which PumpSave makes is that the system curve with existing
control and AC Drive control are the same. In reality this is seldom the case.
In DrivePump SW the two are separate values.
Maximum head H
max
(m)
Enter the discharge head pressure that will be developed by the pump at
full speed and zero flow. The value must be determined from the pump
curve. If the pump curves look complicated select a H
max
which together with
H
n
define a nice second order curve in the range 20….100% Q
n
.
Efficiency,
p
(%)
Enter the efficiency of the pump at volume flow Q
n
. The efficiency value
should be given with the impeller which will be used.
Existing control method
Existing Control Method
Pick the existing control method that you want to compare with ABB AC
Drive control. The control method is selected from the drop-down list on the
upper left part of the sheet. The options are throttling, on/off control, and
hydraulic control.
The smaller energy usage of frequency converter is compared to a large energy
required by:
•
Throttling
which means the liquid flow control is made by throttling valve
and motor and pump is running at full speed and pressure.
•
ON/OFF
which means ON/OFF duty is adjusted according to flow
requirements and a reservoir is available. The control can’t be as good as with
speed control. When pump and motor is running they run at full speed.
•
Hydraulic
which is based on hydraulic drive or some other type of slipping
drive such as an eddy current magnetic coupling drive. The motor is running
with full speed but with slip the pump shaft is controlled.
Motor Data
PumpSave is computing from pump data the required motor output power
including 10% thermal margin. Based on this number you may enter the Motor
power.
Motor power (kW)
Enter the nameplate power rating of the motor. This is used to select the proper
drive rating. The program uses calculated power demand to determine energy
savings.
Supply voltage (V)
Enter the supply voltage used in application. The value should be between 115
(1-ph) to 690 V (3-ph). This is used to screen out some drive types.
Motor efficiency,
m
(%)
Enter the motor efficiency from the motor nameplate or from other data
supplied by the motor manufacturer. Use the efficiency for full load operation
on fixed frequency utility power. The program will adjust the efficiency for
operation at reduced speeds and loads. If the motor is oversized for the
application, enter the efficiency for operation at the maximum applied load.
