Inspection items before screw chiller operation
2.1.1 Inspection of power supply and electronic control instrument system
1) Before the first start-up, check whether the power distribution capacity is consistent with the power of the unit and whether the selected cable diameter can withstand the maximum working current of the host.
2) Check whether the electrical system is consistent with this unit. The electrical system of this unit: three-phase five-wire system (three phase wires, one neutral wire, one ground wire, 380V ± 10%).
3) Check if the power supply line of the compressor is tightly connected. If it is loose, re-tighten it. The torque of the compressor wiring is 500kg.cm. Due to factors such as long-distance transportation and lifting of the host, the screws may become loose. Failure to do so may cause damage to electrical components (such as air switches, AC contactors, etc.) and compressors in the control cabinet of the main unit.
4) Use a multimeter to check all electrical circuits carefully to check whether the wiring is correctly installed in place; use megohm measurement to ensure that there is no short circuit in the casing; check whether the grounding wire is correctly installed in place, and the insulation resistance to ground is greater than 2MΩ; Claim.
5) Check whether a disconnect switch is installed on the power supply line of the unit.
6) All wiring of the main circuit in the control cabinet and external wiring of the control circuit should be checked in accordance with the wiring diagram before being energized (such as crankcase oil heater, compressor electronic protector, circulating water temperature sensor, target flow switch wiring, water pump Joint control, etc.); check whether the terminal bolts are tightened and there is no looseness. Check whether all electrical control instruments and electrical appliances are installed correctly, complete and effective, and check whether there is no foreign matter inside and outside the electrical control cabinet, especially at the connection points of each point.
7) After checking the above items to power on the control cabinet, the power indicator light is on, and the oil heater starts to work, and observe whether the phase sequence protector is normal. If the phase sequence protector is normal (green light is on), close the unipolar switch in the control cabinet. (QF2) The control loop starts to work, and the touch screen (text display) and PLC controller are all put into operation.
8) Before starting, check whether the external system of the unit meets the startup conditions (such as whether the system's cold water pump and cooling water pump are externally controlled or the main interlock. The external control needs to turn on the water pump before turning on the host.
2.1.2 Inspection of compressor and refrigerant piping system
1) Check whether the oil level in the compressor is normal. The normal compressor oil level is generally in the middle of the sight glass.
2) Check whether the compressor capacity adjustment solenoid valve coil is tight and the capacity adjustment capillary is not damaged.
3) All refrigerant valves in the refrigeration system (angle valves at the outlet of the condenser, compressor suction and exhaust shut-off valves) are open to make the refrigerant system unblocked.
4) Check whether the high and low pressure values and the high and low pressure settings of the pressure relay are normal (the high pressure set value is 1.8 MPa and the low pressure set value is 0.2 MPa, the user must not change it without authorization).
5) Check if the compressor lubricant is warmed up for more than 8 hours. Before the test run, heat up the oil heater for at least 8 hours to prevent frothing of the frozen oil during startup. If the ambient temperature is low, the oil heating time needs to be relatively long. Starting at low temperature, due to the high viscosity of the lubricating oil, it may be difficult to start and poor compressor loading and unloading. Generally, the minimum lubricating oil temperature must be above 23 ° C before it can run.
6) Check if the compressor wiring is correct. The compressor shuts down immediately after starting, and observes the instantaneous system pressure change to ensure that the exhaust pressure rises and the return pressure drops. Conversely, the compressor is reversed, and the wiring sequence of the compressor needs to be adjusted again.
7) Perform a trial run with the main circuit disconnected and check that the sequence of actions is normal. The normal startup sequence is: when the power is turned on, the star AC contactor is closed for three minutes after pressing the start button of the unit. After a short time, the star AC contactor is disconnected and the triangle AC contactor is closed. The unit starts to start. The load value starts and loads gradually.
2.1.3 Inspection of water system
1) Check whether the cooling water and chilled water pipes have been washed away, and whether there are debris in the cooling towers, pools and other parts that communicate with the outside. Make sure there are no impurities or foreign objects in the pipes.
2) Check whether the pressure gauge on the water side is connected to the thermometer correctly. The pressure gauge should be installed at 90 ° to the water pipe. The thermometer should be installed to ensure that its temperature probe is directly inserted into the water pipe.
3) Check whether the flow switch on the cooling / cooling water outlet side is installed correctly, and make sure that the flow switch and the control cabinet are correctly wired.
4) Jog the chilled water and cooling water pumps and check the pump steering. The correct direction of the pump should be clockwise, otherwise please check the pump connection again.
5) Turn on the chilled water and cooling water pumps to start the water circulation. Check whether the water pipe is leaking, and whether there is obvious leakage and dripping.
6) Test run chilled water and cooling water pumps. Observe whether the water pressure is stable. Observe the pressure gauge at the inlet and outlet of the pump. When the water pressure is stable, the pressure gauge reading and the pressure difference between the inlet and outlet change slightly. Observe whether the running current of the pump is within its rated operating current range. If the difference between the rated current and the rated value is too large, check the system for excessive resistance, and troubleshoot the system until the actual operating current meets the requirements.
7) Check whether the cooling tower / expansion water tank water supply device is unblocked and whether the automatic exhaust valve in the water system can automatically exhaust. If it is a manual exhaust valve, open the exhaust valve of the chilled water line and the cooling water line to exhaust the internal gas.
8) Adjust the water flow and check whether the water pressure drop through the evaporator and condenser meets the requirements for normal operation of the unit. That is, the inlet and outlet pressures of chilled water and inlet and outlet pressures of cooling units should be at least 0.2MPa.
2.1.4 Check to ensure that other equipment such as cooling tower fans are operating normally without abnormal noise. Check whether the belt tension of the fan is appropriate, and ensure that the fan and motor connection belt does not slip and there is no abnormal noise.
2.1.5 Check whether the terminal equipment of the air conditioner is operating normally, and confirm that the water valves and dampers in all places have been opened. The end equipment can be opened freely without abnormal noise, and the supply air range and wind speed meet the design requirements.
2.1.6 Check whether the PLC program and electrical components work normally. When the power is on normally, the indicator light of the control component in the electric control cabinet is green.