These types of controllers facilitate the installation and commissioning of commercial refrigeration condensing units.
by Carlos Obella*
The commercial refrigeration industry has traditionally been using mechanical pressure controls to control and protect refrigeration equipment.
These conventional controls regulate vital functions within a cooling system and are essential for its proper functioning. In many cases, low-pressure switches, or "low pressure switches," are used to control compressor operation, and act as a low-pressure limit control at a time.
On the other hand, high-pressure switches, or "high pressure switches", can stop the compressor for protection, in case the discharge pressure is excessively high.
Dual pressure controls (Fig. 1 - cover photo) combine low and high pressure control in a single device, through a single contact operated by either.
Other functions of the "pressure switches" include control of condenser fan start and stop cycles and oil pressure safety control.
Mechanical pressure switches have been very useful in the refrigeration industry for many years, and experienced technicians feel very comfortable working with them.
Today, technological advances in the industry have begun to gradually drive the trend towards the application of electronic pressure controls.
Electronics offer greater reliability, simplify maintenance and offer greater flexibility of operation. In view of all these advantages, it is very easy to understand why service technicians are turning more and more towards electronic controls.
This transition can be reflected in the design update of certain products. For example, Emerson Climate Technologies began the transition from mechanical controls to their corresponding electronic versions in refrigeration equipment during the last two years. This is how this company began to integrate electronic controllers (Fig. 2) in its line of condensing units (Fig.3).
Figure 2
In fact, there are already thousands of these electronic controllers operating in the field. Service technicians are beginning to realize the benefits of this change that allows them to make pressure adjustments more simply, accurately and quickly.
Figure 3
Applying more and more electronics is a way to help service technicians become more productive. For example, mechanical pressure controls require around 30 minutes to adjust during commissioning and can be very complicated when configured due to reading difficulties in the scale of the same (Fig 4).
An electronic control requires no more than a minute, sometimes less, for its configuration. In addition to the obvious time savings, the device can be programmed at the touch of a button, rather than using cumbersome tools (Fig. 4).
For those who market condensing units, electronic controllers allow them to optimize inventory levels, since the same unit may be able to operate with multiple refrigerants.
Emerson Climate Technologies' integration of electronic controllers into its condenser unit line reduced the number of models by 45%, without affecting the level of service and availability of products to meet the needs of installers and end users.
Electronic controllers also provide greater reliability, as they allow to reduce the number of components, in addition to reducing the risk of refrigerant gas leaks through capillary connections and threaded joints subjected to vibration.
These technological changes require the refrigeration technician to be trained in the new and advantageous practices of installing condensing units. To do this, we make available informative material and videos on our website http://www.emersonclimate.com/espanol
* Carlos Obella is Technical Director of Emerson Climate Technologies.
