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Header image Energie-to-Components
The Carlo Gavazzi Group

Arc-free compressor switching

As a result of the transition to low-GWP refrigerants, stand-alone systems such as display cabinets, vending machines, ice cream machines and similar equipment using a low refrigerant charge, propane (A3) is almost becoming the refrigerant of choice due to its very low GWP compared to other refrigerants. Like any other A3 refrigerant, propane is flammable. 
The UL/IEC 60335-2-89 standard requires components used in this environment to be arc-free, sealed or have appropriate approvals. Solid-state relays are therefore becoming increasingly popular, as switching is arc-free. The RM1A and RM1B series of solid-state relays are already UL-rated for motor switching and can be used to replace contactors for switching compressors.

Compressor switching with solid state contactors

In larger refrigeration condensing units, compressors can reach up to 5-7.5 HP (10kW). In applications using flammable refrigerants (A3), such as propane, conventional power relays and mechanical contactors cannot be used. Sealed relays can be used, but the disadvantage of these products is their limited electrical life, which can lead to higher maintenance costs and more frequent servicing.  
To solve this problem, solid-state contactors such as the RGC2A can be used to replace mechanical relays and contactors. The RGC2A carries UL approvals and is also certified for motor use. RGC2A is a fully solid state contactor and is also considered as a "non-potentially igniting" component by the UL/IEC 60335 standard. The other advantage of using solid-state contactors is that the lifetime is calculated in millions of cycles, resulting in lower service and maintenance costs. 

Compressor delayed starting with solid state timers

Showcases may require multiple compressors to provide the refrigerant charge necessary to guarantee the cooling capacity required by the larger volume. Control systems, typically temperature controllers, used in these applications tend to be very simple and may not have sufficient outputs and built-in delays to switch compressors sequentially. 
One solution is to use a timer for delayed operation, such as the EASS series. 
The EASS family of mini timers is completely solid-state and is available with screw and quick-connect terminals for faster assembly. The delay time can be adjusted from 0.5 to 10 minutes, depending on the model chosen. In this way, when it is necessary to start several compressors in sequence, the compressors on which the EASS timer is installed in series with the control signal will actually start once the delay time has expired, thus creating a sequential, delayed start.

Single phase compressor soft starters

Refrigerated display cabinets typically use small piston compressors or scroll compressors. Compressor starts are characterized by a high inrush current (typically 5 to 8 times the rated compressor current) leading to voltage sags especially on single phase installations.
Our RSBS single phase soft starters have a built-in current limit to reduce compressor starting current by up to 60% without requiring any user adjustment. The built-in delays between starts protect against short cycling. conditions. Additional built-in protection function ensure that the compressor is protected even under abnormal operating conditions.

Three phase compressor soft starters

In larger refrigeration applications, scroll compressors and piston compressors are commonly used. In a centralized system, the compressor rack will consist of a series of medium sized compressors. In decentralized systems, smaller compressors are directly installed within the display cabinets.
Whichever solution is used, we provide soft starters that can control compressors up to 100 Aac rated current. RSBT is tailored for scroll compressors whereas the more general purpose soft starters, RSGD and RSGT are suited for any compressor typology. Most of our soft starters include Modbus RTU to facilitate data exchange with the PLC for real-time load condition monitoring.

Panel mount solid state relays

Refrigeration compressors may be subject to higher ON/OFF switching cycles to maintain the required temperature. Electromechanical contactors and relays might require periodical maintenance and replacement due to contact erosion due to the higher number of switching. Additionally, deployment of flammable refrigerants within refrigeration industry is also requiring a shift to arc free components.
Our solid state relays (SSRs) are finding their way in display cabinets specifically to switch compressors. We offer SSRs in both contactor like design, like RGS as well as hockey puck type enclosure like RM1B.

DIN-rail mount and panel mount energy meters

Energy optimization in supermarket refrigeration equipment should include energy monitoring as a first approach. By monitoring and comparing energy consumption, areas for improvement can be easily identified.
Our DIN-rail energy meters can measure both single phase as well as three phase loads. Various communication protocols are also available to facilitate integration in existing monitoring systems and PLCs.

Controllers for data aggregation

For larger installations, a number of energy meters can be connected to a central controller for data aggregation. UWP is our universal web platform with remote, on-premise and cloud functionalities.