General
The RCA-RTA series air-cooled water chillers consist of 10 models covering capacities from 234.7 up to 1102.9kW. It is the end result of a thorough study and accurate design by experienced American Breeze research and development team, to develop a large size chiller series with compact shape, high performance, and reliability of the highest quality standards. This series meets the highest levels of aesthetic and technical requirements using the latest technological innovations. RCA-RTA units are ideal for installation in commercial and industrial applications due to their dependability, selected materials and low operating sound levels.

Casing
All units use metal parts that are fabricated from heavy gauge galvanized steel sheets 1.5mm thickness, formed to ensure maximum rigidity that guarantees and preserves the units operation during the years. After fabrication these are degreased, phosphatised, and electro statically powder coated with epoxy-polyester RAL 9002 coating of a thickness of 60-70mu. This fully can successfully withstand a salt spray test of 500 hours, according to STM B-117.
All components are assembled together using bolts thus avoiding the need for welding which may harm the galvanization of the steel and ensures that the whole assembly can fully withstand adverse weather conditions.

Compressor
The product is equipped with 2 semi-hermetic, accessible, screw type compressors and 2 independent refrigerant circuits. All the screw compressors are designed for use with R22 Refrigerant. The compressors consist of twin screw moving in opposite directions, specially made out of steel and are installed in a separate department from the electric motor. The 3 phase 2 pole induction motor is suitable for 400-50Hz network and does not require any heat dissipation as it is cooled by the refrigerant medium itself. A Delta-star startup configuration ensures minimum startup current. The compressors are equipped with continuous (Stepless) capacity control system. In continuous (stepless) capacity control system, a normal open solenoid valve and a normal close solenoid valve are equipped to the inlet and outlet of piston cylinder respectively. These two solenoid valve are controlled by the chiller micro controller, refrigeration capacity control hence can be modulated at anywhere within 25%-100%. Inside the electrical panel an installed microprocessor controls all the safety and operation features of the compressor.

In order to ensure correct operation, the compressors also feature:

• High temperature sensor for the refrigerant medium (PT-100).
• High temperature sensor for induction motor windings (PT-100).
• Low oil level safety switch.
• Differential oil pressure switch.
• Refrigerant gas suction and discharge lines.
• Check valve in discharge line.
• Pressure safety setup ensuring the highly pressurized refrigerant gas is within safety limits.
• Additional cooling through the pressure chamber thermo expansion valve when necessary, through refrigerant liquid spray ensuring temperatures are kept within designated limits.
• The compressors are mounted on special rubbers to absorb noise during the unit's operation.

Condenser coil
All unit heat exchangers are manufactured from high quality inner grooved copper tubes according to ASTM B-280, with an outside diameter of 9,52mm (3/8). The fins are manufactured from aluminium and form the secondary extended heat transfer surface.

The fins are continuous across the heat exchanger and are fabricated in high precision dedicated press lines. The fin surface is waffle formed, so as to increase the fin rigidity, and have special louvers that help increase heat transfer. The combination of internally grooved copper-tubing and louvered fins has resulted in a heat transfer performance 30% superior to that of a conventional coil for this particular application.

Evaporator
All units are equipped with a shell and tube water-direct expansion type evaporator that has two separate cooling circuits, one for each screw compressor.

Condenser fans
Condenser fans are of the axial type directly transmitting motion to the blades, suitable for outdoor installation and pair mounted in-between the V-shaped condenser coils. The 3-phase motors are of closed type, low revolutions, F insulation class and IP-55 protected suitable for frequency inverter usage. The fan motor assembly has a protective grid against accidental contact with moving parts, which is designed according to ISO regulations. Upon request also available is an electrical set-up that controls the fan rpm through a microprocessor depending on the condensation temperature or pressure. Through this set-up the operational pressures of the device depend on the external condition thus increasing energy efficiency.

Microprocessor controller
All units are equipped with an electronic programmable control system. This allows complete management of all the functions of the unit and ensures protection of all vital parts. Over 150 programmable parameters offer complete unit management.

Critical parameters that require control are:

• Start-up / shut down time of compressor.
• Time delay.
• Protection against multiple start-up.
• Water pump time delay in reference to compressor operation.
• Outlet water temperature.
• Discharge pressure.
• Discharge temperature.
• Compressor running current.
• Continuous sophisticated compressor capacity control using multiple parameters.

• Antifreeze protection.
• BMS module interface kit for Bacnet, Trend, LonWorks, connection.
• Connection via internet using a device converting the Caret protocol to 10Mb/s TCP/IP Ethernet protocol.
• Extension memory card for up to five thousand messages.
• Extension memory card 1 & 2 MB.
• Parallel chiller operation with standard controller for up to 2 units (4 compressors).
• Microprocessor parameter reprogramming card.
• R407c or R134a refrigerant.
• Condenser fins made of copper or prepainted aluminium and Blygold treatment for corrosion protection.
• Windscreens (right, left, back).
• Differential water pressure switch.
• Condenser protection guards. Remote Cool / Heat selector switch.