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use a shutdown valve located on the muffler plate to
perform the same function. Neither valve is considered
to have a low leak rate suitable for recycling pumpdown.
Motor Overload Protection
Conventional internal line break motor overload
protection is provided. The overload protector opens the
common connection of a single-phase motor and the
center of the Y connection on three-phase motors. The
three-phase overload protector provides primary single-
phase protection. Both types of overload protectors
react to current and motor winding temperature.
Operating Envelope
The ZP model family is approved, and U.L. recognized,
for use with R-410A only. See Figures 1a and 1b
for the R-410A operating envelope. The envelope
represents safe operating conditions with 20F° (11K)
superheat in the return gas. Please note that the ZP*KW
compressors have a smaller envelope for swimming
pool applications.
Power Supply
All motors for the ZP compressors, whether single
or three phase, with the exception of the "PFV" 208-
230, 1Ø, 60 Hz motor, are designed to operate within
a voltage range of +/-10% of the voltages shown on
the nameplate. For example, a compressor with a
nameplate voltage of 200-230 volts can start and
operate within a range of 180-253 volts. Compressors
with a "PFV" designated motor such as ZP50K3E-
PFV, may only be operated in a range of 197-253 volts
under maximum load conditions.
Accumulators
The use of accumulators is very dependent on the
application. The Copeland Scroll compressor's inherent
ability to handle liquid refrigerant during occasional
operating flood back situations make the use of an
accumulator unnecessary in standard designs such
as condensing units. Applications such as heat pumps
with orifice refrigerant control that allow large volumes
of liquid refrigerant to flood back to the compressor
during normal steady-state operation can dilute the
oil to such an extent that bearings are inadequately
lubricated, and wear will occur. In such a case an
accumulator must be used to reduce flood back to
a safe level that the compressor can tolerate. Heat
pumps designed with a TXV to control refrigerant
during heating may not require an accumulator if
testing assures the system designer that there will
© 2015 Emerson Climate Technologies, Inc.
be no flood back throughout the operating range.
To test for flood back conditions and determine if
the accumulator or TXV design is adequate, please
see the Application Tests section. The accumulator
oil return orifice should be from .040 to .055 inches
(1 – 1.4mm) in diameter depending on compressor
size and compressor flood back results. A large-area
protective screen no finer than 30x30 mesh (0.6mm
openings) is required to protect this small orifice from
plugging. Tests have shown, that in the presence of
very fine debris, a small screen with a fine mesh can
easily become plugged causing oil starvation to the
compressor bearings. The size of the accumulator
depends upon the operating range of the system
and the amount of sub cooling and subsequent head
pressure allowed by the refrigerant control. System
modeling indicates that heat pumps that operate down
to and below 0°F (-18°C) will require an accumulator
that can hold around 70% to 75% of the system
charge. Behavior of the accumulator and its ability
to prevent liquid slugging and subsequent oil pump-
out at the beginning and end of the defrost cycle
should be assessed during system development. This
will require special accumulators and compressors
with sight tubes and/or sight glasses for monitoring
refrigerant and oil levels.
Screens
Screens finer than 30x30 mesh (.06mm openings)
should not be used anywhere in the system with
these compressors. Field experience has shown
that finer mesh screens used to protect thermal
expansion valves, capillary tubes, or accumulators
can become temporarily or permanently plugged with
normal system debris and block the flow of either oil
or refrigerant to the compressor. Such blockage can
result in compressor failure.
Crankcase Heat - Single Phase
A crankcase heater is recommended on single
phase compressors when the system charge amount
exceeds the limit shown in Table 3. A crankcase heater
is required for systems containing more than 120% of
the compressor refrigerant charge limit listed in Table
3. This includes long line length systems where the
extra charge will increase the standard factory charge
above the 120% limit.
Experience has shown that compressors may fill
with liquid refrigerant under certain circumstances
and system configurations, notably after long off
6
AE4-1365 R4
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