Pay attention to compressor low voltage protection
For the parallel compressor unit, in addition to installing a digital pressure sensor for controlling the compressor on and off, a mechanical pressure protection switch is required to set the last protective barrier for the compressor.
The low suction pressure of the compressor has become one of the problems that often occur during the operation of the equipment.
Most of the compressor low-voltage protection that occurs during the commissioning of the equipment is caused by the unreasonable setting of the pressure protection switch. In particular, a parallel unit consisting of multiple compressors starts the shutdown procedure when the parallel unit controller detects that the pressure value of the sensor is lower than the set pressure. If the stop interval between the two compressors is set slightly longer at this time, and before the last compressor is stopped, the compressor suction pressure value is lower than the protection pressure set by the mechanical pressure switch, resulting in low suction pressure. Call the police. This requires everyone to pay attention during the equipment trial run.
This problem is often encountered for units that are already in normal operation after the end of the test run. At this time, many friends will still think that the value of the mechanical pressure switch adjustment is unreasonable, and the alarm value of the mechanical pressure switch will be directly lowered. In fact, this is a misunderstanding. For the problems that occurred during this period, it is necessary to personally measure the pressure drop before and after the filter installed on the return line, and accurately obtain the value of the suction pressure at the inlet of the compressor. If the pressure drop through the suction filter is too large, a new suction filter must be replaced. If only the wrong value of the mechanical pressure protection switch is adjusted incorrectly, the pressure difference between the compressor inlet and the filter will be larger and larger, and the suction pressure after the filter will be lower and lower, which will greatly reduce the working efficiency of the compressor and increase. Risk of failure of compressor operation.