Technical data

4
© 2008 Emerson Climate Technologies
Printed in the U.S.A.
AE-1318 R1
Application Engineering
BULLETIN
discharge gas overheating. Events such as loss of
charge, evaporator blower failure, or low side charging
with inadequate pressure will cause the discharge gas
to quickly rise above a critical temperature. Once this
critical temperature is reached, the ASTP feature will
cause the scrolls to separate and stop pumping but
allow the motor to continue to run. After the compressor
runs for some time without pumping gas, the motor
protector will open. Depending on the heat build up
in the compressor, it may take up to two hours for the
ASTP to reset. The addition of the Advanced Scroll
Temperature Protection makes it possible to eliminate
the discharge line thermostat previously required. A
graphic explanation and a short video clip are available
on the web site, www.emersonclimatecontractor.com/
ASTP. Compressors with this feature will have the
Advanced Scroll Temperature Protection label (Figure
2) located directly above the terminal box.
Discharge Line Thermostat
The addition of the Advanced Scroll Temperature
Protection on the ZB50, ZB58, ZB66, ZB76, ZB88,
ZB95 and ZB114, as well as the internal discharge
temperature protection described in the section
titled “Motor Protection” for the ZB56, ZB68, ZB75,
ZB92, and ZB11M, makes it possible to eliminate the
discharge line thermostat in most applications.
Pressure Controls
Both high and low pressure controls are required
and the following are the minimum and maximum set
points. Refer to Table 4 for proper settings.
IPR Valve
The 7 through 15 horsepower refrigeration scroll
compressors DO NOT have an internal high pressure
relief valve. To provide safe operation, a high pressure
control set no higher than 445 psig must be used in all
applications (reference Table 4).
Motor Protection
The larger horsepower refrigeration scroll compressors
have either line break protection or the use of sensors
with an electronic module. The type of protection is
obtained from the protector code in the model number.
Table 5 lists the various models protector number and
the type of protection.
For the INT69SCY, there are fi ve PTC (positive
temperature coeffi cient) internal thermisters connected
in series that react with avalanche resistance in the
event of high temperatures. Four of the thermisters are
TABLE 4
PRESSURE CONTROL SETTINGS
Model Control
Type
R404A/R507 R134a R22
ZB50, ZB58,
ZB66, ZB76,
ZB95, ZB114
Low
High
17 psig min.
454 psig max.
4 psig min.
263 psig max
37 psig min.
381 psig max
ZB88 Low
High
N/A
N/A
N/A
N/A
37 psig min.
381 psig max
ZB56, ZB75, ZB68,
ZB92, ZB11M
Low
High
17 psig min.
454 psig max.
4 psig min.
263 psig max
37 psig min.
381 psig max
TABLE 5
MOTOR PROTECTION
Models with Line Break Protection
ZB50, ZB58, ZB66, ZB76, ZB88, ZB95, ZB114
(note: electric code = TF*)
No module
Models with Electronic Module
ZB56, ZB68, ZB75, ZB92, ZB11M
(note: electric code = TW*)
p/n: 071-0620-00
Model: INT69SCY
Models with Electronic Module
ZB95, ZB114
(note: electric code = TW*)
p/n: 071-0641-00
Model: INT69SU