Refrigerant Circuit, Microprocessor Controls

FORM 201.18-EG1

REFRIGERANT CIRCUIT

•Independent refrigerant circuits per compressor, each using copper refrigerant pipe formed on com- puter controlled bending machines. This eliminates over 60% of system piping brazed joints as com- pared to designs that use fittings, resulting in a highly reliable and leak resistant system.

•Liquid line components include: manual shut-off valve with charging port, high adsorption removable core filter-drier, solenoid valve, sight glass with mois- ture-indicator, and reliable thermostatic expansion valves.

•Economizer is a refrigerant to refrigerant, compact plate-type heat exchanger to maximize chiller ca- pacity and efficiency by subcooling liquid refrigerant delivered to the cooler expansion valve. Constructed of corrosion resistant stainless steel plates formed to induce turbulent flow and enhance heat transfer, then oven brazed and pressure tested for reliability. Designed and constructed in accordance with ASME and TÜ V for 450 PSIG (31 bar). U.L./CSA listed.

•Suction and discharge lines provided with manual compressor shutoff service valves. Suction line equipped with closed-cell insulation.

•Oil separators with Design Working Pressure of 450 PSIG (31 bar) and U.L. listing are high efficiency, augmented aerosol impingement type to maximize oil extraction without fragile media to break down.An oil charging valve is included with each refrigerant circuit.

•Oil cooling provided by dedicated air cooled finned tube type heat exchanger located in the condenser section of the machine.

MICROPROCESSOR CONTROLS

•Controls housed in a powder painted steel cabinet enclosure, equivalent to NEMA 3R/12 (IP55), with hinged, latched, and gasket sealed, door.

•Liquid crystal 40 character display with text provided on two lines and light emitting diode backlighting for outdoor viewing.

•Color coded, 32 button, sealed keypad with sections for Display, Entry, Setpoints, Clock, Print, Program and Unit On/Off.

•Standard controls include: brine chilling or thermal storage, automatic pump down, run signal contacts, demand load limit from external building automa- tion system input, remote liquid temperature reset input, unit alarm contacts, evaporator pump control, automatic reset after power failure, automatic sys- tem optimization to match operating conditions, soft- ware stored in non-volatile memory (EPROM) to eliminate chiller failure due to AC power failure. Programmed setpoints retained in lithium battery

backed RTC memory for a minimum 5 years.

•Display – In English (°F and PSIG) or Metric (°C and Bars) units, and for each circuit:

♦Return and leaving chilled liquid, and ambient tem- perature.

♦Day, date and time. Daily start/stop times. Holi- day and Manual Override status.

♦Compressor operating hours and starts. Auto- matic or manual lead/lag. Lead compressor iden- tification.

♦Run permissive status. No cooling load condi- tion. Compressor run status.

♦Anti-recycle timer and anti-coincident start timer status per compressor.

♦Suction (and suction superheat), discharge, and oil pressures and temperatures per System.

♦Percent full load compressor motor current per phase and average per phase. Compressor ca- pacity control valve input steps.

♦Cutout status and set-points for: supply fluid tem- perature, low suction pressure, high discharge pressure and temperature, high oil temperature, low and high ambient, phase rotation safety, and low leaving liquid temperature.

♦Unloading limit set-points for high discharge pres- sure and compressor motor current.

♦Liquid pull-down rate sensitivity (0.5°F to 5°F/ minute in 0.1°F increments).

♦Status of: evaporator heater, condenser fans, load and unload timers, chilled water pump.

♦“Out of range” message.

♦Up to 6 fault shut down conditions.

♦Standard Display Language is English, with Op- tions for: French, German, Italian, and Spanish.

•Entry – Enter set point changes, cancel inputs, ad- vance day, change AM/PM.

•Setpoints – Chilled liquid temperature, chilled liq- uid range, remote reset temperature range.

•Clock – Time, daily or holiday start/stop schedule, manual override for servicing.

•Print – Operating data or system fault shutdown his- tory for last six faults, and software version. Print- outs through an RS-232 port via a separate printer (by others).

•Program –

♦Low leaving liquid temperature cutout, 300 to 600 second anti-recycle timer, lag compressor start time delay, and average motor current unload point. Liquid temperature setpoint reset signal from YORK ISN or building automation system (by others) via:

YORK INTERNATIONAL