Thought energy from the people at Virtjoule

From the Blog


Niwot Market refrigeration monitoring converted to Virtjoule Juice Cellular CT’s

Posted by randy on July 15th, 2014 at 9:27 am


Several months ago, Virtjoule converted the vibration sensors on four compressors at Niwot Market over to the Virtjoule Juice Cellular CT.  Because there were two large Copeland compressors on each rack, there was a lot of vibration from one compressor being picked up on sensors for other compressors, what we call “cross-talk”.

Our goal for Virtjoule Juice Cellular CT was to isolate the runtime of each compressor by itself, making it easier to visually and programmatically analyze what was going on.

Remote mounting board for Cellular CT's

Remote mounting board for Cellular CT's

Key Points

CT’s are very good at isolating runtime behavior of components in more complex or integrated system of machines.

CT’s can be run a very long distance from the source to the Virtjoule sensor, 100′ or more.

Virtjoule Juice Cellular CT’s are like having someone standing with a clamp meter on a machine 24/7.

Need To Know It’s Running

The primary thing Bert Steele, owner of Niwot Market, needs to know is whether the compressors are running or not.  Oil temperature problems, refrigerant changeover, refrigerant leaks, and plain old worn out compressors have caused numerous problems over the time.  All of those problems have caused shutdowns on these critical compressors.  Sometimes it was a single compressor.  Sometimes the whole rack.  Virtjoule’s monitoring service and its ability to tell him his compressors are running has been critical to running a tight margin grocery business.

The compressor racks at Niwot Market have been one of the toughest environments for the Virtjoule vibration input sensors.  There are four compressors total, two each on a rack.  Because these are heavy compressors, when one operates it will vibrate the entire rack.  We were still able to distinguish one compressor from another via vibration, but analysis was more difficult and not as clear to the customer as we would have liked.

Niwot Market Low Temperature Rack

Niwot Market Low Temperature Rack

CT Installation

It’s easy to install CT’s.  Simply pull the top off the CT, wrap the body of the CT around the alternating current wire you’re interested in, and put the top back on.

Magnelab 70 amp CT on one of three phases

Magnelab 70 amp CT on one of three phases

The CT Run

In this installation, the compressors are in a basement room, underneath a corrugated metal and concrete floor, and situated near the center of the building.  Needless to say, cellular coverage from this location was not good.  We were able to find a location in a stairwell that gave us good cellular reception, but was still out of the way, yet accessible.


Virtjoule Juice Cellular CT’s can easily isolate and monitor electrical components such as large electric motors, compressors, fans and blowers, chlorine generators, sump pumps, air conditioners, walk-in and reach-in refrigerations, and many more types of critical electric machinery.

With amperage information, you can not only make power estimates, you can use Virtjoule’s 10 second data to determine if the machine is running, how often it’s cycling on and off, how long those cycle times are, and produce critical alerts via text, email, or callout.

[Randy Cox - CEO and co-founder of Virtjoule - He is the software designer and analytics engineer for Virtjoule Sense sensors. He studied Chemical Engineering and Petroleum Refining at the Colorado School of Mines. You may contact Randy at: randy at virtjoule dot com] – See more at:

Print Friendly

Leave a Reply

two + 4 =