INTRODUCTION

PETRA Air-Cooled Liquid chillers  APSc with semi-hermetic screw compressors and R407c refrigerant, offer a wide range of sizes to meet customer requirements for different applications. PETRA APSc chillers offer state of the art low sound, reliability, high energy efficiency and small physical footprints.

PETRA APSc chillers are designed to be shipped as a complete factory package which are 100% test run in the factory.

The range of capacities in PETRA’s  APSc series the range is from (47 to 435) nominal tons at 50 Hz and from (54 o 493) nominal tons at 60 Hz.

PETRA APSc chillers consist of high efficiency, low-pressure drop coolers and V- shaped condenser coils to maximize airflow.

PETRA APSc chillers are equipped with a microprocessor controller with unsurpassed features capable of managing unit performance for optimum efficiency at both full load and part load values.
 

OUTSTANDING FEATURES

Superior Efficiency

The APSc series exceeds the new ASHRAE 90.1 efficiency levels at both full and part load efficiency.
 

Low Noise Chillers

The APSc chillers offer low sound power levels, measured in accordance with the BS ISO 3744 standard.
 

Compact Physical Footprint

The APSc chillers feature compact footprints and the possibility for close- spacing installation to serve the areas that have space constraints.
 

Outstanding Finishing

All copper pipes and headers are acra clad painted after being cleaned, to ensure pipe material and brazing are protected against all external conditions. All coil U-Bends are protected with a painted galvanized steel cover plate which covers the whole U-Bend coil side. Suction lines and other insulated pipes are wrapped in cheese-cloth and epoxy painted. This gives further protection for insulation against weather and other factors.
 

Compressor

• Suction gas-cooled semi-hermetic screw compressor &Universal application &Rain-tight terminal box &High-efficiency profile & Double-walled
  pressure - compensated rotor housing, which is extremely stable and results in additional sound attenuation.

• Proven, long - life bearings with pressure unloading.

• Optimized oil management. Built in directly flanged on oil separator, long life fine filter mesh and magnets on oil circuit, pressure relieved bearing
  chamber ensures minimum refrigerant dilution in the oil.

• Large volume motor for part winding or direct start with integrated PTC sensor in each winding.

• Intelligent electronics including thermal motor temperature monitoring phase sequence monitoring, manual reset lock- out and discharge
  temperature protection by PTCs sensors.

• Dual capacity control with infinite and slide control

• Automatic start unloading
 
• Discharge shutoff valve and discharge check valve
 

Quality Assurance

To ensure the best performance, all the chillers in the APSc series are:
 
• Factory test run

• Produced in an ISO 9001-2000 listed manufacturing facility.

• Rated in accordance with ARI standard 550/ 590.

• Constructed in compliance with the ASHRAE 15 safety requirements.

Easy Installation

Installation is made quick and easy with complete factory wiring, easy lifting provisions, factory installed options and start-up. To eliminate potential start-up problems, a complete factory test run is performed on each unit.
 

Design Flexibility

The APS chillers meet the same high engineering and performance standards that are characteristics of all PETRA air- conditioning systems. A wide range of capacities and options for the APSc series are available to meet precise design requirements.

• Rubber-in-shear isolation.
 
•Oil level switch, high efficiency suction strainer, oil strainer

•Crank case heater and built in safety pressure relief valve.
 

Air Cooled Condenser

PETRA'S air-cooled condenser coils are designed to deliver their duties with optimum performance for all design conditions. Coils are manufactured from seamless copper tubes mechanically expanded into aluminum fins. All coils are air pressure tested at 450 Psi, under water to avoid leakage. They also undergo dry cleaning after manufacturing for optimum system cleanness.

Type-L, heavy wall, seamless copper tubes are provided for the coil headers. The condenser coils are hydrostatic pressure tested in accordance with the UL 1995 standard.
 

FEATURES AND BENEFITS

Direct Drive Condenser Propeller Fans

All condenser fans are of the propeller axial type, which are directly mounted on the motor’s shaft. All fans run at approximately 900/1100 RPM (50/60Hz), for optimum fan efficiency and maximum sound power reduction. Fan blades are made from coated steel or aluminum for maximum corrosion resistance, and are statically and dynamically balanced before installation.

PETRA also provides its "Patented Design" for the condenser fan mounting. This new design offers low noise operation with high efficiency performance. All condenser fans are equipped with wire guards.
 

Condenser Fan Motor

All fan motors are of the high efficiency, six pole, squirrel-cage induction type motors. They are totally enclosed, air-cooled, permanently lubricated, have internal thermal current protection and with class "F" insulation. All motors are IEC certified.
 

Coolers

High efficiency shell and tube type coolers with inner grooved tubes to optimize the cooler’s efficiency.

Coolers are tested and stamped for refrigerant side working pressure of 225 Psi and for waterside working pressure of 150 Psi. These working pressures comply with applicable sections of the ASME standard, and the European codes ISPESL and TUV.

Cooler water baffles are fabricated from brass for maximum corrosion resistance. Coolers are provided with water vents and drain connection plugs and are insulated using (3/4 inch) closed cell foam insulation as a standard insulation thickness. Other thicknesses are available as options.
 

STANDARD FEATURES

Construction

• Galvanized C-channel chiller base with lifting lugs painted with Acrylic Polyurethane paint

• V-shaped, air-cooled condenser allows less installation space requirements

• Modular design with multiple compressor execution provides flexibility for varying load conditions and avoids total shut down of the chiller during
  servicing of any of the refrigeration circuits.

• Easily accessible system components

• Weatherproof with ample space for easy access to power and control panels

• Heavy duty mounting chassis for the whole unit coated with weatherproof, polyester powder electrostatic paint, oven-baked to ensure maximum
  gloss and hardness.

• Anti-vibration mounts under compressor (rubber pad type)
 

Refrigeration

• Independent refrigeration circuit per compressor

• Liquid, discharge and suction pipes are all of hard copper pipes. They are formed using the highly accurate CNC pipe bending machines in
  order to minimize pipe-brazed joints which in turn increases system reliability.

• Components of each refrigeration circuit:
         - Expansion valve
         - Liquid line solenoid valve 
         - Liquid line shut off valve
         - Liquid line moisture indicator sight glass 
         - Replaceable core type filter 
         - Fully charged unit with R407c refrigerant
         - High safety pressure switches(Capsule type; factory pre-set)

• Acra clad paint for all exposed copper piping system of the refrigeration circuit

• Liquid injection kit

• Stepless capacity control for each compressor (25-100)%
 

Electrical

• Inherent motor protection for each compressor

• Part winding start

• Inherent motor protection for each condenser fan motor

• Smart lead-lag operation for compressors

• Free terminal for remote ON/OFF connection

• Free terminal for general alarm output

• High ambient kit

• Control voltage is 220-240V for all components

• Power supply monitor (phase failure relay).

• Single point power connection for each electrical panel (refer to electrical data tables)

• Starting contactors for compressors and condenser fan motors

• Automatic pump down control

• ON/OFF switch for each compressor

• Control circuit breaker for short circuit protection

• Circuit breaker for each compressor

• Short cycling protection for compressors (time delay)

• Control transformer sized to supply the needs of the control circuit, sourcing power from the main unit power connection

• Microprocessor control for full management of the chiller operation and safety circuits

• Control terminal strip for easy connection with electrical board and easy field installation

• Head pressure control by the simple ON/OFF condenser fan motor according to ambient temperature down
 

OPTIONAL FEATURES

Construction

• Chiller sound enhancement (Options) There are three options to enhance the chiller sound pressure level:

                a- Compressor compartment with standard fan

                b- Ultra low fan speed720 rpm/900 rpm (50/60Hz) and compressor with compartment

                c- Special design fan blades with external rotor motor and compressor with compartment

• Coils protection material There are three options for coils material:

                a- Polyurethane precoated aluminum fins with copper tubes

                b- Copper fins with copper tubes

                c- Polyurethane post coat copper fins with copper tubes

• Galvanized steel wire mesh guard around the chiller’s perimeter

• Cooler cladding can be aluminum, stainless steel or polyester painted (22 gauge) galvanized steel

• Chiller Vibration Isolation The following options are available for chiller vibration isolation:

               a- Neoprene rubber pads

               b- 1 inch spring isolator
 

Refrigeration

• Cooler tape heater: Factory installed heater to protect cooler from freeze-up at low ambient down to (-20°F)

• Ice storage option: Special chillers are available for this option, please consult PETRA factory for more details

• Glycol option: Used for applications requiring water outlet temperature below 40°F

• Suction valves for compressors larger than 90 HP

• Suction accumulator

• Liquid receiver

• High pressure relief valve

• Pressure gauges (High + Low)

• Water flow switch: Required as a safety interlock to prevent operation of the unit without evaporator flow (available for field installation only).

• Electronic expansion valve &Cooler insulation: Cooler can be insulated with 1.5 inch thick or more closed cell foam
 

Electrical

• Low ambient head pressure control

• If the chiller is intended for use in low ambient conditions (below 45°F), low ambient control must be added. This can be achieved by
  varying the speed of the condenser fan motor by using a variable frequency drive. The speed of the condenser fan motor can be regulated
  with reference to the high- pressure sensor to maintain constant condensing pressure in the condenser.

• Unit mounted fused or non-fused disconnect service switch with external handle to isolate unit from power for servicing.

• Ground current protection for whole unit power supply. The current is monitored by toroidal coils around the power leads

• Building automation system connection.

• External overload for each compressor.

• External overload for condenser fans.

• Ampere meter and/or voltmeter installed on the electric panel door.

• Circuit breaker for condenser fan motors.

• Main power circuit breaker for the whole unit with door isolator.