WPSa

Water Cooled Water Chiller with Screw Compressor

Petra’s water cooled liquid chillers (WPSa) with a wide range of capacities and exceptionally high efficiencies, were designed to meet customer requirements for a variety of applications.

Petra WPSa chillers offer state of the art low sound, high quality and reliability, optimized performance and a compact physical footprint.

Petra WPSa chillers with semi-hermetic screw compressors and R-134a HFC refrigerant are 100% factory tested and commissioned to ensure efficient performance at specified operating conditions.

• The WPSa series meets or exceeds the new ASHRAE 90.1 efficiency levels at both full and part load efficiency.
• The WPSa series is available as a door way or extended chassis design
• The WPSa chillers feature compact footprints and are suitable for close-spacing installation to serve the areas that have space constraints.
• To ensure the best performance, all the chillers in the WPSa series are factory-run tested, produced in an ISO 9001-2015 listed manufacturing facility & certified according to AHRI standard 550/590.
• 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.
• Suction lines are insulated with closed cell foam insulation, then wrapped with a special protective material and finally epoxy coated. This gives further protection for the insulation against weather and other factors.
• Other exposed copper pipes and headers are epoxy coated after being cleaned, to maintain pipe material and brazing protected against external conditions.
• Petra paint is certified according to ASTM 117 A&B 5000 hours salt spray test.

• Welded structural C-channel base painted with mono component catalyzed primer sprayed paint.
• Base is equipped with welded brackets for heavy duty lifting lugs.
• Structural members are made from gauge 15 [1.8 mm (0.07 inch)] tubular cross members that are semi welded with stainless steel fasteners. All members & panels (side & roof) are painted with oven baked polyester electrostatic powder paint.
• Suction gas-cooled semi-hermetic twin screw compressor with variable slide valves allow the chillers to match actual load conditions, delivering exceptional part load performance.
• High efficiency direct expansion (DX) shell and tube type coolers and condensers with inner grooved tubes to optimize the cooler’s efficiency.
• Coolers and condensers are tested and stamped for refrigerant side design pressure of 1,000 kPa (145 Psi) and for a maximum water side working pressure of 1,500 kPa (220 Psi).
• Independent refrigeration circuit per compressor.
• Liquid, discharge and suction pipes are all hard copper pipes. They are formed using automated CNC pipe bending machines in order to minimize pipe-brazed joints which in turn increases system reliability.
• Epoxy paint for all exposed copper piping system of the refrigeration circuit.
• Components of each refrigeration circuit include liquid line solenoid valve, liquid line shut off valve, liquid line moisture indicator sight glass, high safety pressure switch and replaceable core type filter
• Unit is fully charged unit with R-134a refrigerant.
• Electronic expansion valve: Electronically Operated Step Motor flow control valves, intended for the precise control of liquid refrigerant flow. Synchronized signals to the motor provide discrete angular movement, which translates into precise linear positioning of the valve piston. Easily interfaced with microprocessor based controllers.
• Compressor electronic current monitor and overload protection through controller.
• Free terminal for remote ON/OFF connection.
• Free terminal for general alarm output.
• Control voltage is 220-240V for all components.
• Single point power connection for each electrical panel.
• Circuit breaker for each compressor.
• – ON/OFF switch for each compressor.
• Control circuit breaker for short circuit protection.
• Short cycling protection for compressors (time delay).
• Control transformer mounted & wired that shall supply all unit control voltage from main unit power supply to internal components such as (not limited to) solenoid valves, compressor motor protector, compressor crank case heater and microprocessor controller.
• Microprocessor controller for full management of chiller operation and safety circuits.
• Power supply monitor (phase failure relay) used to protect the power circuit against over or under voltage conditions and against phase loss or loss reversing conditions.
• Nema 3X with IP54 minimum enclosure standard electrical panel. Two separate panels, one for power & the other for control.

• Hot gas bypass consists of a mechanical valve capacity regulator used to adapt compressor capacity to actual evaporator load, installed in a bypass line between the high and low pressure sides of the refrigeration system and is designed for hot gas injection into the evaporator just after the expansion valve.
• Pressure gauges for monitoring of refrigeration discharge and suction pressure.
• Pressure relief valve set to open at a predetermined set pressure to protect pressure vessels and other equipment from being subjected to pressures that exceed their design limits.
• Water flow switch installed to prevent operation of unit without evaporator water flow
• Cooler cladding of aluminum, stainless steel or painted galvanized steel {made from gauge 22 [0.7 mm (0.03 inch)}.
• Cooler can be insulated with closed cell foam insulation of 25 mm (1 inch), 38 mm (1.5 inch) & 50 mm (2 inch) The insulation density is 48 kg/m3 (3 lb/ft3) with a K-factor of 0.035 W/(m.°K) [0.0203 BTUH/(ft.°F).
• Main disconnect switch used to de-energize the power supply to the chiller during servicing or repairing works because of the door interlock with an external handle that is installed on the electric panel door.
• Power factor correction used to improve the power factor level which improves system reliability, minimizes voltage drops and gives better power quality.
• Control transformer to supply power input to auxiliary components at 120 or 220 volts, such as (not limited to) bulk head light and GFI outlet.
• IP 54 protection, class I electric safety bulk head light.
• Ampere-meter & volt-meter used to measure the power current & voltage consumption Ampere-meter is used for each phase.
• 120 volt power supply connected through the transformer to provide a 120 volt single phase circuit that is used to operate the electric appliances at site such as laptops, tablets and cell phones.
• External over load for each compressor.
• Nema 4x electrical panels made from galvanized steel.
• Nema 4x electrical panels made from stainless steel.
• Cooler tape heater protection down to 0°C (32°F), -18°C (0°F) & -29°C (-20°F).