C6.3.2/0416-0716/E
5
2.5.2 Application limits
For application envelopes please refer to Copeland brand products Select software available at
2.6 Design features
2.6.1 Compressor construction
All compressors are fitted with Discus valve plates which cannot be dismantled. To maintain the
high capacity of these compressors in case of exchange, the correct valve-plate-to-body gasket
must always be selected.
The 4M*D and 6M*D Digital head is fitted on the terminal box side cylinder bank.
All 6M*D compressors are equipped with a standard capacity control on the central cylinder
bank.
Each cylinder head has a plugged 1/8" - 27 NPTF tapped hole for connecting high-pressure
switches.
These high-pressure switches must be calibrated and tested before putting the compressor into
service. They must stop the compressor if the allowable pressure is exceeded.
The complete cylinder head is under discharge pressure.
Figure 2: Exploded view of the Digital mechanism
Factory-delivered 4M*D and 6M*D compressors include as standard configuration:
one standard bank;
one Digital modulated bank;
one capacity-controlled bank (blocked suction std)
only for 6M*D
.
NOTE: To upgrade 6M* compressors to 6M*D, Emerson Climate Technologies
recommends to use the central cylinder bank.
2.6.2 Digital theory of operation
Digital technology is now available on the 4M*D and 6M*D Stream compressors. Applied to one
bank on a 4M*D compressor it provides 50 to 100% capacity modulation. When combined with a
blocked suction bank on a 6M*D compressor, it provides 33 to 100%.
Digital capacity control is achieved by using a proven internal unloading method, based on
blocking gas to the valve plate suction area. Capacity control can be achieved by varying the
percentage of duty cycle when the compressor is loaded and unloaded. The unloader piston
mechanism that controls the flow of suction gas into the cylinders is driven by a solenoid valve.
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