Emerson Copeland Scroll ZPV066, Бюллетень

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© 2017 Emerson Climate Technologies, Inc.
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AE4-1414
If off-cycle migration control is required, and no off-
cycle migration testing across the range of expected
indoor/outdoor temperatures is performed, the stator
heater must be powered to at least 100 Watts when
the compressor is 'off'. To use fewer than 100 Watts
or to comply with future DOE requirements for off-
cycle power consumption, off-cycle migration testing
must be performed. A 70 watt crankcase heater may
be used instead of the motor windings to provide heat
to the base.
CAUTION Stator heat for off-cycle migration must
not be energized when the system is in a vacuum
or if there is no refrigerant charge in the system.
The system low pressure cut-out control can be
used as an indicator of the presence of refrigerant
charge.
Manifolded Compressors
Multiple compressor assemblies are available for
purchase from Emerson. In lieu of purchasing the
assembled manifold, the OEM can choose to
purchase the manifold-ready compressor and perform
the assembly in their factory. Drawings of tandem and
trio compressor assemblies are available from
Emerson by contacting your Application Engineer.
NOTICE: Customers who choose to design and
build their own manifolds for tandem and trio
compressor
assemblies are ultimately
responsible for the reliability of those manifold
sets.
The suction manifold is close to a symmetrical layout
with the design intent of equal pressure drop to each
compressor. A straight length of pipe is connected to
the suction manifold "T" connection to serve as a flow
straightener to make the flow as uniform as possible.
The discharge manifold is the less critical of the two
manifolds in terms of pressure drop. Low pipe stress
and reliability are its critical design characteristics.
Support for the discharge manifold between the
compressors should be no closer than a straight
distance of 14" (356 mm) from the discharge tee.
For tandem compressor applications, tubing stress
levels should be closely evaluated. If excess stress
levels occur, the Resonance Avoidance Feature in the
Emerson EVC drive may be used.
Manifolded Applications
Manifolded compressors follow the same application
guidelines as single compressors outlined in this
bulletin. The refrigerant charge limit for manifolded
compressors is shown in
Table 4 . A manifolded
circuit with charge over the limit must have a
crankcase heater or stator heating applied to both
compressors.
Oil levels in the individual sight-glasses will vary,
depending on whether one or more compressors in
the manifolded set are operating and if the manifolded
set is made up of equal or unequal compressor
capacities. Because of the unequal oil levels that can
exist, oil levels should be viewed with the
compressors off to allow the oil level to stabilize
between
the compressor sumps. With the
compressors off, oil should be visible in the individual
compressor sight-glasses.
Suction and discharge manifolds are not designed to
support system piping. Support means must be
provided by the system designer to support suction
and discharge lines so that stress is not placed on the
manifolds.
The compressors in a manifolded set can be
started/stopped in any desired sequence. To help
reduce inrush current, starting the compressors
individually is recommended. Should a compressor
fail in the tandem set the complete tandem should be
removed from the unit and replaced with a new
tandem set. Replacing individual compressors is
discouraged because of the care that must be used
when installing the oil equalization tube and the
availability of manifolds to the aftermarket.
Please consult with Application Engineering
during the development of systems with trio
compressor
assemblies. Trio compressor
assemblies are sensitive to system operating
conditions and configurations which will affect oil
balancing. Trio compressor assemblies must be
qualified for each application.
Manifolded compressor assemblies are available for
purchase from Emerson. In lieu of purchasing the
assembled tandem, the OEM has the option to
purchase the tandem-ready compressors to assemble
the compressors into a tandem configuration.
Drawings of the tandem manifolds are available by
contacting your application engineer. Manifold ready
compressors are designated with a -4XX bill of
material number at the end of the model number (e.g.
ZPV0662E-4X9-455).
Customers that choose to
design and build their own manifolds for tandem
and trio compressors are ultimately responsible
for the reliability of those manifold sets.