Control Specification (15/18/24 Class) SiUS04-70248 Function and Control4.2 Frequency ControlOutline Frequency will be determined according to the difference between room and set temperature.The function is explained as follows.1. How to determine frequency.2. Frequency command from an indoor unit. (The difference between a room temperature and thetemperature set by the remote controller.)3. Frequency command from an indoor unit.4. Frequency initial setting.5. PI control.Detail How to Determine FrequencyThe compressor’s frequency will finally be determined by taking the following steps.For Heat Pump Model1. Determine command frequency Command frequency will be determined in the following order of priority.1.1 Limiting frequency by drooping function Input current, discharge pipes, low Hz high pressure limit, peak cutting, freeze prevention, dewprevention, fin thermistor temperature.1.2 Limiting defrost control time1.3 Forced cooling1.4 Indoor frequency command2. Determine upper limit frequency Set a minimum value as an upper limit frequency among the frequency upper limits of thefollowing functions:Compressor protection, input current, discharge pipes, Low Hz high pressure, peak cutting,freeze prevention, defrost.3. Determine lower limit frequency Set a maximum value as an lower limit frequency among the frequency lower limits of thefollowing functions:Four way valve operating compensation, draft prevention, pressure difference upkeep.4. Determine prohibited frequency There is a certain prohibited frequency such as a power supply frequency.Command frequency Limit frequency Skip controlUpper limit functionCompressor protection functionLower limit functionFour-way valve operating compensation, etc. (*)Initial frequencyPI controlDefrost control (*)Drooping functionInput current control, etc.Upper limit frequencyFMAXLower limit frequencyFMINTarget frequencyCommand frequency X repeats when frequency becomes lowerFrequency changes by PI control < repeats when frequency becomes lower*; only for heat pump model(R2831)
