York YK M3 M3 G4 Oil Heater, Motor Driveline, Heat Exchangers, Refrigerant Flow Control

oil pump sooner, depress the MANUAL OIL PUMP key again.

On shutdown of the system for any reason, the oil pump operates and continues to run for 150 seconds. The system cannot restart during that time interval.

OIL HEATER

During long idle periods, the oil in the compressor oil reservoir tends to absorb as much refrigerant as it can hold, depending upon the temperature of the oil and the pressure in the reservoir. As the oil temperature is lowered, the amount of refrigerant absorbed will be in- creased. If the quantity of refrigerant in the oil becomes excessive, violent oil foaming will result as the pres- sure within the system is lowered on starting.This foam- ing is caused by refrigerant boiling out of the oil as the pressure is lowered. If this foam reaches the oil pump suction, the bearing oil pressure will fluctuate with pos- sible temporary loss of lubrication, causing the oil pres- sure safety cutout to actuate and stop the system. See “Control Center, Section 2”.

To maintain the lowest possible concentration of re- frigerant in the oil, the compressor oil reservoir is equipped with a 115 volt electric reservoir oil heater. The oil heater is thermostatically controlled at all times during compressor shutdown to maintain the sump oil at 145°F to 155°F. If the oil temperature falls below 55°F, the display will read

SYSTEM SHUTDOWN – PRESS STATUS .

Pressing the STATUS key causes the message to read DAY 10:00 AM – LOW OIL TEMP – AUTO START . The system will be allowed to automatically restart when oil tem- perature rises to 30°F above condenser temperature.

MOTOR DRIVELINE

The compressor motor is an open-drip-proof, squirrel cage, induction type constructed to YORK design speci- fications. 60 hertz motors operate at 3570 rpm. 50 hertz motors operate at 2975 rpm.

(For 60 hertz motors 1750 HP and smaller; and 50 hertz motors 1400 HP and smaller) . . . the open motor is provided with a D-flange, factory mounted to a cast iron adapter mounted on the compressor.

(For 2000 HP 60 hertz motors; and 50 hertz motors above 1400 HP) . . . a separate structural steel base is furnished to provide rigid mounting of the compressor and motor, independent of the evaporator shell, to en- sure controlled alignment of the assembly. Motor is mounted with final alignment at start-up.

Motor drive shaft is directly connected to the com- pressor shaft with a flexible disc coupling. Coupling has all metal construction with no wearing parts to assure long life, and no lubrication requirements to pro- vide low maintenance.

For units utilizing remote electro-mechanical starters, a terminal box is provided for field connected conduit. Motor terminals are brought through the motor casing into the terminal box. Jumpers are furnished for three- lead type of starting. Motor terminal lugs are not fur- nished. Overload/overcurrent transformers are fur- nished with all units. For units furnished with factory packaged Solid State Starters, (optional) see right.

HEAT EXCHANGERS

Evaporator and condenser shells are fabricated from rolled carbon steel plates with fusion welded seams.

Heat exchanger tubes are internally enhanced type.

The evaporator is a shell and tube, flooded type heat exchanger. A distributor trough provides uniform distri- bution of refrigerant over the entire shell length. Alumi- num mesh eliminators are located above the tube bundle to prevent liquid refrigerant carryover into the com- pressor. Two 1-1/2" liquid level sight glasses are lo- cated on the side of the shell to aid in determining proper refrigerant charge. The evaporator shell con- tains a dual refrigerant relief valve.

The condenser is a shell and tube type, with a dis- charge gas baffle to prevent direct high velocity im- pingement on the tubes. A separate subcooler is lo- cated in the condenser.

The removable compact water boxes are fabricated of steel. The design working pressure is 150 psig and the boxes are tested at 225 psig. Integral steel water baffles provide the required pass arrangements. Stub-out wa- ter nozzle connections with Victaulic grooves are welded to the water boxes. These nozzle connections are suitable for Victaulic couplings, welding or flanges, and are capped for shipment. Plugged 3/4" drain and vent connections are provided in each water box.

REFRIGERANT FLOW CONTROL

Refrigerant flow to the evaporator is controlled by a single fixed-orifice (or variable orifice).

Chillers can be provided with a REFRIGERANT LEVEL CONTROL (EPROM version C.02.F(T).13 or later sup- ports this feature). A level sensor senses the refriger- ant level in the condenser and outputs an analog volt-

40 YORK INTERNATIONAL