Standby Control; Startup Control - Midea V8 Series Service Manual

3 Standby Control

3.1 Crankcase Heater Control
The crankcase heater is used to prevent refrigerant from mixing with compressor oil when the compressors are stopped. The
crankcase heater is controlled mainly according to the minimum of discharge temperatures.
When the minimum of discharge temperatures is above 45°C, the crankcase heater is off;
When the minimum of discharge temperatures is below 40°C, the crankcase heater turns on if one of the three following
conditions is matched:
1. The first time powered on
2. In defrost operation
3. Ambient temperature < 10 °C and the compressor stops for more than 4 hours

4 Startup Control

4.1 Startup Sequence and Frequency Control in Combination Modules
During the start-up process, the control of the compressor and the heat exchange mode is uniformly judged by the master
outdoor unit, and the electronic expansion valve and solenoid valve are self-judged by the salve unit according to its own
sensor status.
During the start-up process, the compressor frequency is based on the displacement frequency of the 60cc compressor.
After the main outdoor unit is weighted and evenly distributed to each slave unit according to the maximum frequency, each
slave unit performs the displacement frequency and convert it to actual frequency.
When combinational modules are started in parallel, the master outdoor unit is started first, and each slave outdoor unit is
started with a delay of 5s.
4.2 Compressor Startup Delay Control
In initial startup control, compressor startup is delayed for 3 minutes in order to let the master unit search for the indoor
units' addresses.
In restart control (except in oil return operation and defrosting operation), compressor startup is delayed such that a
minimum of 3 minutes and a maximum of 12 minutes has elapsed since the compressor stopped, in order to prevent
frequent compressor on/off and to equalize the pressure within the refrigerant system.
V8/V8i PRO VRF 50Hz
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