Up To Speed: SubDrive Pressure Transducer Versus Pressure Sensor—Why Not Both?

06/21/2018

Up To Speed Graphic Thin VersionUp To Speed  is a concise, technical blog compiled by industry veteran Mark Reeder. It provides an interesting fact, answers a thought-provoking question, or offers a cliffhanger from an actual site visit by one of our world-class Field Service Engineers.

In a previous post, we discussed two pressure switch options available for SubDrive®—the pressure transducer versus the pressure sensor. Both communicate the system pressure to the variable frequency drive (VFD). Once the system pressure is known, the VFD can continually adjust the pump and motor speed to maintain a constant pressure. A pressure transducer is an electronic device, offering the ultimate in flexibility and options. A pressure sensor, or Hobbs switch, is a basic mechanical device with unparalleled reliability. Both devices are used in a myriad of applications beyond water systems.

Sensor And TransducerA pressure transducer (left) and pressure sensor, or Hobbs switch (right), ensure ultimate reliability and flexibility with your Franklin Electric pressure controls.

But did you know Franklin Electric’s SubDrive has separate connections for the pressure transducer and pressure sensor? During installation, you can easily wire in both pressure switch options, ensuring ultimate reliability and flexibility, using a simple tee.

As a contractor, this trick of the trade is gold. Unconvinced? Just ask Wisconsin-based Franklin Electric Field Service Engineer Tony Eisinger.

“After 35-plus years in the industry, you learn to think outside the box. When coming off the water tank, connect both the transducer and Hobbs switch (pressure sensor) into each side of a three-quarter-inch tee,” Tony said.

Next, connect both the transducer and the sensor connections into their respective connections on the SubDrive control board. Franklin Electric has two VFD options—the SubDrive UtilityTM and the SubDrive ConnectTM. The SubDrive Utility comes standard with a pressure sensor, while the SubDrive Connect is paired with a pressure transducer. Depending on your VFD, purchase the extra needed piece to take advantage of this trick.

SubdriveThe SubDrive Utility (left) comes standard with a pressure sensor, while the SubDrive Connect (right) comes standard with a pressure transducer.

Of course, when wiring both connections into the control board, make sure the pressure sensor is connected to the “PS” or “pressure sensor” input, while the pressure transducer is connected to the “XDCR” or “pressure transducer” input. It’s also important to tell the unit which device you are using via the DIP switch—most likely you will use the more precise pressure transducer, with the pressure sensor in place as a backup option with a simple flip of the DIP switch or by using the FE Connect App when you want to quickly restore water.

Subdrive TransducersMake sure the pressure sensor is connected to the “PS” or “pressure sensor” input, while the  pressure transducer is connected to the “XDCR” or “pressure transducer” input. 

FE Connect AppThe FE Connect App can be used to switch control options from the pressure transducer, to the pressure sensor.

“In the event of transducer failure, all you have to do is shut the power off, go in, flip a switch, turn the power back on, and you’re good to go in five minutes,” Tony said.

It’s the best of both worlds—and affordable insurance.

Now, you’re up to speed.