Danfoss Turbocor TT Series, Service Manual

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Figure 2-2 Cooling Inlet Adapter
Liquid refrigerant is internally channeled to two (2) solenoid valves. These valves have integral orifices that act as
expansion devices to cool the compressor motor, shaft (rotor) and power electronics. TTS300 and TGS230
compressors have these solenoids arranged so that all components are cooled in series with each other and the
solenoids act as two (2) stages of cooling capacity. The TTS350, TTS400, TTS450, TTS500, TTS700, TTH375, TGS310,
TGS380, TGS390, TGS490, TGS520, and TGH285 compressors have separate cooling paths for motor and power
electronics. These cooling methods are identified as serial or split cooling.
Serial cooling has its return point to the inlet of the first-stage impeller, thus cooling all components with refrigerant
evaporating at the saturated suction temperature. In serial cooling versions, Solenoid One (1) is opened if any
temperature reaches its “turn on” point and Solenoid Two (2) is opened if any temperature reaches a second “turn
on” point value. Refer to Figure 2-5 Compressor Cooling Path - TTS300/TGS230 on page 37.
The split cooling has the motor/shaft cooling circuit return to the first-stage impeller inlet and the power electronics
return to the second-stage impeller inlet. This ensures a higher evaporating (cooling) temperature to minimize
condensation around the power electronic components. In the split cooling version, Solenoid One (1) is opened if
either the cavity temperature or the motor temperature reaches its “turn on” point and Solenoid Two (2) is opened if
the Inverter or SCR temperature reaches its “turn on” point. Refer to Figure 2-4 Split Cooling Path - (TTS/TGS (Except
TTS300/TGS230 Serial Cooling)) on page 36.
Medium temperature (MT) version compressors require their motor cooling suction line to be vented externally to
the main suction line through an evaporator pressure regulating (EPR) valve. This valve is required to ensure that
evaporating temperatures cooling the motor and electronics do not get too cold. The EPR valve should be adjusted
to maintain a minimum evaporation temperature of 0.8°C (34°F). Refer to the TTS/TGS/TTH/TGH Applications Manual
for further details.
Serial Cooling compressors can be identified by having only one 1/4 inch flare Schrader connection adjacent to the
main motor cooling liquid connection, while a split cooling model will have two (2). These 1/4 inch flare connections
access the refrigerant feeds to the components being cooled and bypass the solenoid valves. A minimum pressure
ratio of 1.5 and a full liquid seal at the compressor is required to ensure proper and correct compressor cooling.
Page 34 of 294 - M-SV-001-EN Rev. H 1/23/2023