SubDrive75 Frequently Asked Questions

In the SubDrive series, the pump can be different than the motor hp size.

Example:
The SD75, used with a 3/4 hp pump on 1.5 hp motor, provides the performance similar to the 1.5 hp standard curve in the same pump series. In other words, you will be using a ¾ hp pump to get the performance of the 1.5 hp curve in the same series... use the 1.5 hp curve when choosing the proper ¾ hp pump to use. Refer to the installation manual for more information.

The SubDrive75 will spin the pump at a rate that will produce constant pressure without overloading the motor or exceeding a maximum speed of 80 Hz (@ 4,800 rpm). This means that the speed of the pump may exceed the conventional speed of 3,450 rpm. As speed increases, head increases by the square of speed (exponentially), so you get a lot of head performance with just a small increase in speed.

Any pump that is in the same pump series as the rated drive pump and is appropriate for the desired head and flow performance.

It is possible to use a 1 hp pump on a 1.5, 3-phase motor, but it is important to remember that you will still get the performance of the 1.5 hp curve in that series and the SW1 switch must be changed to represent the pump selected. Use of the 1 hp pump is recommended only in flow ranges where a 1 hp pump is available but a ¾ hp pump is not.

The range of operation for a SubDrive75, 100, 150 and 300 is as listed: Minimum = 1,800, Maximum = 4,800 rpm The range of operation for a MonoDrive and MonoDriveXT is as listed:

Minimum = 1,800, Maximum = 3,600 rpm

Currently, the only option for repair of a damaged SubDrive controller is replacement. However, replacement fans are available in the event of a fan becoming damaged.

The SubDrive is equipped with premium surge protection. It is designed to withstand a Voltage surge of 6,000 Volts for 28 microseconds. MOVs (Metal Oxide Varistors) are used to protect the SD75 input and output terminals from Voltages above 1,200 Volts. These are the same devices used in computer surge protectors, and serve the same function in protecting the electronics from surges experienced during thunderstorms.

Yes. The SubDrive is air-cooled and is therefore not dependent on uninterrupted water flow between the wellhead and controller.

The SubDrive75/100/150/300 have a power factor correction feature to keep Voltage and current constantly in phase (power factor = 1). This minimizes amp draw on the input side, and significantly improves Voltage distortion on the input side. Power Factor correction reduces heat stress on the main supply transformer to the house, thus extending its life. This makes the utility company happy and avoids the additional fees being considered in the future for utility customers with poor power factor loading.

The size of the leak and the capacity of the tank used will determine the run time of the pump. If we use the smallest tank possible, it would require a leak of approximately 1 cup per minute to drive the pump continuously. Larger diameter tanks would require a higher rate to cause continuous pumping. This, however, is not specific to the SubDrive alone. All variable speed drive systems would react similarly. Additionally, power consumption in this case would be very low due to the fact that the pump is turning at minimum revolutions. Also, since the SubDrive has a soft start (no in-rush current), the motor is not stressed during starting as much as it is in a conventional system.

Depends on application... In general, you should get some energy savings if average daily flow is more than approximately 3 to 5 gpm.

The pressure switch tells the controller to speed up the motor if the pressure is below the pressure setting and to slow down the motor if the pressure is above the pressure setting. IT IS NOT CONSTANTLY TURNING THE MOTOR ON AND OFF. The result is a continuous ramping up and down around the pressure set point. This "pressure dither" may or may not be visible at the gauge, but is generally not noticeable at a faucet or tap.

Millions of cycles. This sensor is rated for 500 psi. It is a heavy-duty sensor that carries less than 5 Volts. It does not carry load, so there is no arcing and consequently much less deterioration of the contact points compared to conventional pressure switches. The range of motion of the contacts is very small (millimeters), and there is no "snap action" involved. The result is a very durable sensor.

The orifice has been enlarged to a maximum diameter and we don't expect to have obstruction problems from particles or chemical build-up (calcification, iron deposits). Since the orifice of the SubDrive pressure sensor is larger than most, if not all standard pressure switches, there is less chance of obstruction compared to conventional systems. Although mounting orientation is not usually a problem, you should NOT mount the sensor in an inverted orientation (with black part down). This could allow the orifice to collect debris and block the pressure sensing capability of the sensor.

No, the SD NEMA 1 and control box use a different enclosure.

The breaker size depends on the drive and line Voltage:

Yes, a SubDrive with a NEMA 4 or NEMA 3R enclosure can be used outside. A NEMA 1 enclosure is rated for indoor use only.

At this time, SubDrive is not recommended for applications other than Franklin powered submersible pumps.

Franklin Electric recommends the use of a FE motor and SubDrive to comply with UL certification and to maintain compliance with the FE warranty policy.

Please reference the page 23 of the SubDrive Installation Manual (M1560 Rev3) for cable sizing information.

The SubDrive may not operate properly with generators unless the following guidelines are followed:

The generator should be capable of supplying single-phase, 230 Vac, 50 Hz or 60 Hz power, with a minimum continuous rating indicated in the chart below:

(Refer to the generator installation guide for grounding and safety considerations. The generator ground along with both L1 and L2 power connections should be made to the SubDrive).

When using the SubDrive as the only load it is recommended to add a parallel lamp load of about 450 Watts. This serves to improve the output regulation of the generator. This can be implemented with two 225 Watts, 125 V lamps (mounted in appropriate fixtures), connected in series. The series connection of the lamps would then be connected across the 230 Vac source. (With the generator running, the intensity of the lamps should remain constant indicating that the generator is maintaining constant output regulation of the 230 Vac line. If the lamp intensity fluctuates, the generator is having difficulty maintaining output regulation and it may be necessary to reduce the water demand to lighten the load from the generator.)

When considering multiple loads from a generator, the various types of loads can be critical for their effect on output regulation. In a case like this it would be best to contact the generator vendor for further guidance. Likely recommendations would be to specify a generator with a significantly higher power rating than the total of the expected loads, and to include a parallel lamp load.

Yes, however FE advises contacting the inverter manufacturer to assure a clean 60Hz sinusoidal wave is provide at the output inverter for best SubDrive operation.

No. The SubDrive uses a standard Franklin Electric motor. Refer to the Installation Manual for motor horsepowers.

The SubDrive75 manual indicates that "The CP Water SD75 controller is intended for indoor use and for operation in ambient temperatures up to 104 °F (40 °C)". This specification is based on an input line Voltage to the SubDrive75 of 190 Volts (RMS). We have done further testing to determine the performance of the SubDrive75 at higher ambient temperatures with 230 Volt (RMS) input. The results of our testing indicate that the SubDrive75 should be able to provide full power in ambient temperatures as high as 125 °F (51.6 °C).

Yes, but for best practice a SubDrive NEMA1 should be regarded in the same light as a personal computer. For applications outside or with the potential for excess moisture, a NEMA3R or NEMA4 enclosure is recommended.

In this case, it is possible that the pump has reached its maximum performance for the flow demanded. At this point, the performance will follow the curve as in the case of a conventional pump (see graph below).

Another way that pressure at a particular tap may drop is simply due to restriction in the plumbing. If a faucet shares a branch with another tap, pressure at one may drop when the other is opened simply because there is restriction to that branch. Restriction increases with smaller pipe diameter, longer runs, or more elbows and tees. If the gauge reading agrees with the pressure setting but faucet pressure drops when another tap opens, the pressure drop is due to restriction downstream of the sensor.

If there is distance between the gauge and the pressure sensor, the pressure at the gauge can appear to rise and fall as flow varies. This is due to restriction between the gauge and the sensor. As flow increases, the difference between the pressures at the sensor vs. the gauge will be greater. The best practice is first to mount the pressure sensor on the home side of the pressure tank. Placing the sensor 12 inches downstream per every 1 inch diameter of pipe to avoid turbulence at the tee and then mount the gauge close to the sensor.

The maximum amp draw (S.F. Load) on a SubDrive (motor lead from the controller to the motor) corresponds to the S.F. amps listed in the AIM manual.

The SubDrive will shut off.

Consult your FE distributor for a specialty motor to work in a high temperature environment.

Due to the nature of the RFI filtering process in the SubDrive, a GFCI will most likely be tripped on start-up and the motor will not run.

Yes. If the output leads to the motor are connected incorrectly, the motor will run in reverse. The first indication of this is typically a much lower production of water. The solution is to switch any two of the output leads.