12
C6.2.15/0815/E
3.3.2 Tubing recommendations
IMPORTANT
This tube has been tested and qualified at 50 and 60 Hz operation for
running stresses and resonance in a single compressor lab environment.
However, in some compressor applications such as racks and transport
applications, the OEM is strongly advised to re-confirm the acceptability of
the tube when the compressor is subject to additional vibration inputs.
The tube from the solenoid to the suction (
Figure 17
) should be as short as possible (less than
7.5 cm). Dimensions for a typical tube going from the top of the compressor are shown in
Figures 18 & 19
.
3.4 Tandem compressors
Copeland Scroll Digital compressors ZRD48K* to ZRD81K* and ZPD54K* to ZPD91K* can be
used in a Tandem arrangement (code 422 in nomenclature), if the single compressor cannot
cover the required capacities and/or there are higher fluctuations in capacity demand. The
fittings for gas equalization and oil equalization must be connected between the two
compressors (see
Figure 20
).
Figure 18: Tandem configurations for compressor combinations with 3 to 15 hp models (ZR and ZP ranges)
Specific dimensional drawings and technical information documents on system oil balance
control to build qualified Tandem design units are available upon request from Emerson Climate
Technologies.
It needs to have an OEM-system control device providing the signals for common operation,
modulation as well as for single compressor operation. In general the architecture of such a
system controller runs the digital compressor continuously and cycles only the standard
compressor if the capacity demand drops below, eg, 40% of the total capacity.
The standard compressor should join the Digital Scroll compressor operation when the capacity
demand comes to a value of about more than, eg, 60 to 65% and stays on for a defined amount
of time. Any percentage of capacity modulation within the capacity range can be achieved by
switching the cycle time algorithm of the Digital compressor as a reaction to the system
behaviour.
Copeland Scroll Digital compressors ZRD125K* and ZPD103K* to ZPD182K* require some
extra attention for tandemization in terms of oil balance. Emerson Climate Technologies has
worked out a redesign of the Schraeder valve position and qualified an oil balancing system just
via these connections. Models capable for this configuration must have been built from 1
st
of
October 2009 onwards, serial number 09J…!
A combination or a mix of models built before
this date is not released.
The common suction return line must have a straight height of at
least 400 mm before joining the T-connector (see
Figure 21
).