The AK2-SC 255 has a color display available in both medium and high resolution, and an ergonomic keypad that includes context-sensitive soft keys whose functions - indicated across the bottom of the display screen - change according to the type of information displayed. The soft keys provide direct navigation to supporting service screens and data displays.

"We designed the controller's human-machine interface after interviewing and observing refrigeration and air conditioning service technicians, installers, and store personnel," said Paul Friedlander, R&D director at Danfoss in Baltimore. "That way we know we have a product that is intuitive and comfortable for users."

The controller interface can be changed from English to Spanish (and other languages) and back at any time during operation, on site or remotely.

A feature of the new controller is an on-board Ethernet port for remote communications via LAN/WAN or Internet.

There is also support for a standard telephone modem. The manufacturer has developed a software product designed to provide network access to the new controller while maintaining network integrity and security.

Also new is Pocket Manager that runs on a manager's wireless PDA. From any place in the store, it is possible to check temperatures and alarms, according to the company.

Refrigeration Controls

Features for refrigeration control include a patent-pending algorithm for controlling electronic evaporator pressure regulating (EEPR) valves. The new algorithm provides tightly regulated suction-side temperature control based on conditions in the most-loaded fixture on a circuit, the company said.

Also being introduced is a new stepper motor EEPR valve. EEPR use is increasing in supermarket refrigeration because well-controlled electronic valves have a considerable efficiency advantage over mechanical EPRs, said Chris Shaffer, North American product manager for Adap-Kool.

"Electronic EPRs offer precise temperature control, and, as a result, the circuit will operate at peak efficiency. And because they are part of the Danfoss electronic control network, EEPRs are remotely adjustable, too, with set points easily verified from maintenance offices, too."

To support the new stepper motor EEPR valve, and also those produced by other manufacturers, Danfoss is offering an output module designed to enable interface with up to four EEPR valves.

The modules are mounted on DIN rail and joined by interlocking slide connectors. The connector system contains the communications and power conductors for the entire lineup of modules.

Communications and power wiring are connected to a single power and communications module that serves up to nine input and output modules. Installation wiring is reduced because there is no need to run power and communications lines to each module, the company said.

Input and output modules are supplied in a number of configurations, and point-for-point are from 50 percent to 75 percent more compact than other interface products on the market, according to the company. The new system controller is more compact than its predecessor, the AKC 55, said the manufacturer.

The modular concept allows for scalability and flexibility of the control system. Modules can be added, removed, or replaced as needs change.

If a department is added to the store, or remodeled, it is a relatively simple matter to accommodate the changes by adding or reconfiguring control module lineups, the company said.

The initial offering of modules for the AK2 system consists of eight digital outputs, eight digital outputs and eight universal (analog or dry contact) inputs, eight universal inputs, eight low-voltage digital inputs, eight high-voltage digital inputs, and four bipolar stepper outputs. Modules with digital outputs are available with or without override switches.

Publication date: 09/06/2004