How To Use the Watlow Aspyre Power Controller Bake-out Feature

Hi, I'm Nathan Ehresman with Valin Corporation and I'd like to welcome you our video series on thermal  process improvements. In this video, we will be focusing on how to increase productivity, which is a key initiative for any company wanting to increase market share in today’s challenging economy. We will be focusing on the Watlow Aspyre power controller and its role in helping increase productivity.

The Aspyre is Watlow’s most innovative power controller. Its features include heater bake out, an amazingly easy-to-use interface, enhanced serviceability, and it has the capability to be configured from a USB. The Aspyre is optimally designed to get your plant up and running fast: reducing installation and start-up time and- especially- reducing down time of large heater systems. Let’s get into it!

Electric heaters are hygroscopic, which means that they can suck water right out of the air. Heaters that have been in storage for extended periods (or even high temp heaters that have been out of commission during a shutdown) can absorb enough moisture to create a path to ground, thus shorting  out the heater and rendering it useless. This can be easily tested with an Ohm Meter (see our video on heater failure).

If your heater is wet, you can send it to Valin and our well-trained team can bake the heater out in one of our ovens, sending it back to you with a complete diagnostic report and a solid MegOhm reading. However, this does take some time, and if you are in a tight turnaround, time could be a luxury you can’t afford.

The Watlow Aspyre has a built-in heater bake out function that can save you a great deal of time when commissioning either a new heater, or one that has been in storage. Simply switch the Aspyre into “bake out mode” and it will gradually increase the voltage applied to the heater; slowly warming it up without applying sufficient voltage to arc to the sheath. Soon, your heater will be warm and dry and ready to go back to work at full capacity. I have been on countless job sites where a heater has been decommissioned for a long period of time and has absorbed enough moisture to be considered “wet”. The operators either a. fire it up and blow out the heater or b. spend days wrapping the heater in blankets, trying to force the moisture out through the terminal pins. This is a long and painful process that can be dramatically shortened by using the heater bake out option on the Aspyre.

How does the Aspyre do this? By regulating voltage, the Aspyre is able to vary the height of the sine wave, which in turn directly affects the current going into the heater. This is different than a standard SCR, which applies full voltage for a limited time. For example, if we call for 50% power, say on 240V, a standard SCR will apply 240V for 15 seconds, then zero volts for 15 seconds, then 240V for 15 seconds, and so on. When compared over the course of a minute, or 10 minutes, or an hour, this is 50% power.

But in the case of a wet heater, that hit of full voltage could be enough to short to the sheath. In contrast, the Aspyre will regulate the voltage, applying first (for example) 100V, the 120V, then 180V, slowly baking out the heater until it is dry enough to accept the full 240V

When installing a new SCR power controller, or when troubleshooting an existing one, the process can be complicated and confusing. Oftentimes there is a row of lights or diodes with little or no indication of what the lights mean. Does a lit red diode indicate an alarm condition (and if so, what kind of alarm?) or does it meant that the SCR is energized and power is flowing through? Owner’s manuals are long and take time to download and scroll through, especially on a job site.

By contrast, the Aspyre has a backlit user interface screen with instructions and error codes in plain English, making it easy to set up, easy to program, and a snap for diagnostics.

Don’t want to use the interface screen? No problem! You can also connect the Aspyre to your laptop and use Watlow’s easy configurator to set up the controller in minutes. In my many hours of troubleshooting power controls, I have come to appreciate the value of easy to use diagnostic tools. Oftentimes it ties back to the set-up function- the SCR is looking for a 0-5 VDC signal and your feeding it a 4-20 mA. That is really hard to tell from dip switches and small red diodes. The Aspyre, either through the display or by connecting it to a computer solves this problem in a matter of seconds, increasing throughput and getting your plant back up and running faster and with less hassel.

For scenarios where you have multiple Aspyre units, you can also upload the configuration from one Aspyre into a USB drive, and then download the configuration into others simply by plugging it in and importing the parameters

Call us with all of your process heat and control questions at (855) 737-4718 or e-mail us at Thanks again for watching!