Hitachi YUTAKI Series - Page 152

Controller pack
Service Manual
150
Safety and control device setting
SMGB0066 rev.0 - 12/2009

Thepurposeofthiscontrolistocorrectthediscrepancyofopening,ifany,beforeatroubleoccursintherefrigerantcycle.
Ifrstfullyclosestheexpansionvalveopeningandthenrecoverstothepredeterminedopening.

Selects the initial opening by determining between hot start or cold start from the state of discharge gas temperature (Td)
and outdoor air temperature (Ta) upon compressor startup.

This is a drive control to prioritize the closing operation in order to ensure the discharge super heat (TdSH) calculated From
discharge pressure (Pd) and discharge gas temperature (Td) after compressor startup.

Controls the expansion valve opening to achieeve the target TsSH (SH set) by performig Pl calculation based on the inlet
gas super heat (TsSH) calculated by suction pressure (Ps) and inlet gas temperature (Ts).

Aftercompressorstop(realoperationfrequency=0Hz),retainforonethreesecondstheexpansionvalveopening
immediatelybeforethestop,andthenmaketheexpansionvalveopening“o”pulse.

This is a control to fully close the expansion valve opening during normal operation.