How it Works
The Franklin Electric SubDrive is designed to be part of a system that consists of only four components:
A. Standard Pump and Franklin Electric Motor
B. SubDrive Controller
C. Small Pressure Tank (see Table 4, pg. 14)
D. Franklin Electric Pressure Sensor (provided)
Pressure
Sensor
Leads
Power Supply
from Circuit Breaker
PUMP
MOTOR
A
D
B
C
Pressure
Relief Valve
Power to Motor
SubDrive controllers provide the ultimate in system performance, utilizing Franklin Electric’s three-phase motor series
for maximum starting torque, high efficiency and smooth operation. SubDrives convert residential single-phase 60 Hz
power into the variable-frequency three-phase needed by the motor. In addition, SubDrives can spin a smaller pump
slightly faster to boost output to roughly double its 60 Hz horsepower rating. This allows use of smaller pumps for less
system cost. If a smaller pump of the desired flow rating is not available, the controller can be configured to use larger
pumps up to the horsepower rating of the motor.
Constant Pressure
The Franklin Electric SubDrive provides consistent pressure regulation using advanced electronics to drive a
standard motor and pump according to the pressure demands indicated by a highly accurate, heavy-duty, long-life
pressure sensor. By adjusting the motor/pump speed, the SubDrive can deliver constant pressure dependably, even
as water demand changes. For example, a small demand on the system, such as a bathroom faucet, results in
the motor/pump running at a relatively low speed. As greater demands are placed on the system, such as opening
additional faucets or using appliances, the speed increases accordingly to maintain the desired system pressure.
Motor Soft-Start
Normally, when there is a demand for water, the SubDrive/MonoDrive will be operating to accurately maintain system
pressure. Whenever the SubDrive/MonoDrive detects that water is being used, the controller always “ramps up” the
motor speed while gradually increasing voltage, resulting in a cooler motor and lower start-up current compared to
conventional water systems. In those cases where the demand for water is small, the system may cycle on and off
at low speed. Due to the controller’s soft-start feature and sensor’s robust design, this will not harm the motor or the
pressure sensor.
System Diagnostics
In addition to regulating pump pressure and accurately controlling motor operation, the SubDrive/MonoDrive
continuously monitors system performance and can detect a variety of abnormal conditions. In many cases, the
controller will compensate as needed to maintain continuous system operation. But if there is high risk of equipment
damage, the controller will protect the system and display the fault condition. If possible, the controller will try to
restart itself when the fault condition subsides.
5
Technical changes without notice / Techn. Änderungen vorbehalten / Modifications techniques réservées sans préavis / 5930
