18 AGL_HP_VS_YHV_RG_RT_EN_Rev00
NOTE: For detailed specifications and instructions on how to connect the sensor to the drive,
please refer to the ED3 & EV3 User Manuals. Also see Assembly Instructions C30.11 "NTC
Mounting Recommendations".
NOTE: Refer to the operating map and to section 3.7 "Discharge gas temperature protection"
above for maximum operating discharge line temperatures.
3.7.3 Discharge temperature control mode
In the lower part of the envelopes (Control Suction Superheat), the suction gas at the compressor
inlet has to be superheated without liquid droplets. For superheat requirements please also refer to
section 2.6.2 "Application limits
Operating envelopes".
In the upper part of the envelope (DLT Control) with operation at low evaporating and high
condensing with superheat control mode, the discharge temperature will exceed the limit of 135 °C
inside the application envelope
also see section 3.7 "Discharge gas temperature protection".
In this area, the expansion valve of the evaporator is to be controlled not by superheat but by the
discharge line temperature so that some liquid droplets return to the compressor to cool it down. The
discharge line temperature DLT must be controlled to stay between minimum 120 °C and maximum
135 °C.
The transition from superheat control to discharge line temperature control is demand-driven by the
discharge line temperature. In this transition phase, the discharge line temperature control and
superheat control must be balanced by the system controller. The superheat at compressor inlet
should be reduced gradually to 0 K, to ensure smooth operation (and avoid sudden temperature
changes) as well as compressor reliability. As the requirement to move to discharge line temperature
control depends on several variables (system design, ambient temperat
precise and universal boundary in the compressor envelope where this will systematically happen.
It is therefore up to the user to define by system tests if and when (where in the envelope) the DLT
control is required.
3.8 Solution with SEC Mono
Emerson has developed an optional solution with controller SEC Mono to control the ref rigerant
circuit with matched pairs of compressors YHV*RG/RT with ED3/EV3 drive.
The main functionalities provided are:
compressor speed and operating map control according to section 2.6.2 "Application limits
Operating envelopes";
electronic expansion valves control:
o standard superheat
o in
K
o discharge temperature control according to section 3.7.3 "Discharge temperature control
mode";
control to reverse the cycle;
alarm management and protection functions;
oil return function;
NOTE: Only in combination with this controller YHV*RG and YHV*RT compressors are
K in continuous operation in heating mode with counterflow
operation of the evaporator.
NOTE: For more details on SEC Mono please contact the Application Engineering department
at Emerson.
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