After the unit is installed in place, install the water system pipes, or connect the arranged water system pipes with the unit evaporator and condensation The general requirements for the connection of the water pipe mouth of the heater are as follows:
1. The inlet and outlet water pipes shall be connected according to the identification requirements on the unit. The general regulations are as follows: the condenser water pipe goes in and out from the bottom; The refrigerant connecting pipe side of the evaporator is the chilled water inlet side.
2. The water system must be equipped with a pump with proper flow and lift to ensure the normal water supply of the unit. In addition to the shockproof soft joint connection between the water pump and the unit and the water system pipeline, the support shall also be provided to prevent the unit from being stressed. Welding during installation shall avoid damage to the unit.
3. Install flow switches on the outlet pipes of evaporator and condenser. Interlock the flow switch with the input contact in the control cabinet. Installation requirements: There should be at least 5 times of pipe diameter straight pipe sections on both sides of the flow switch ； Do not install it near bends, orifices and valves; To prevent the flow switch from shaking, all gases in the water system shall be discharged 。 Adjust the flow switch to make it separate when the water flow is lower than the minimum flow (the minimum flow is 40% of the design flow). When the water flow meets the requirements, the water flow switch shall remain closed.
4. The water filter must be installed before the water inlet pipe of the unit. The water system is designed to withstand water pressure and cannot be used under overpressure to prevent damage to the evaporator and condenser.
Condenser line connection
Note: The cooling water outlet pipe must be equipped with a branch pipe for winter drainage, and the inlet and outlet of the cooling water pipe must be equipped with a bypass pipe for pipeline cleaning and maintenance.
1. The cooling water pipe system must first be installed with shockproof flexible joints, thermometers, pressure gauges, drain valves, stop valves, water filters, check valves, target flow controllers, etc., and then connected to the cooling tower inlet and outlet water pipes. See the figure below.
2. The water supply pipeline shall be as short as possible, and the specification of the pipeline shall be determined according to the effective lift of the pump, pipeline flow and flow rate, rather than the connector specification.
3. The water inlet direction of the condenser can be changed according to the user's requirements. Pay attention to the following points when making changes:
Confirm the correct position of the diaphragm and use new rubber sealing ring; When disassembling the water chamber end cover, tighten the bolts in a certain order: tighten the first bolt slightly, and then tighten the bolt at 180 °. Continue to tighten the third bolt in this order, and then slightly tighten the fourth bolt 180 ° from the third bolt. And so on.
Pipe connection of evaporator
1. The chilled water pipeline system must be equipped with shockproof flexible joints, thermometers, pressure gauges, water filters, electronic descaling devices, check valves, target flow controllers, exhaust valves, drain valves, stop valves, expansion water tanks, etc.
2. The expansion tank shall be installed 1~1.5m above the highest point of the system (floor type constant pressure water make-up device can also be used). The water tank capacity is about 1/10 of the water volume of the whole system. The evaporator barrel is equipped with drain and exhaust joints.
3. Thermometer and pressure gauge shall be installed on the straight pipe section of the water inlet and outlet pipeline to avoid installing them too close to the elbow. Each low point shall be equipped with a drain joint to drain the residual water in the system. Before operating the unit, connect the stop valve to the drain pipe and install it near the inlet and outlet connections. There should be bypass pipes between the inlet and outlet pipes of the evaporator to facilitate pipeline cleaning and maintenance. The use of flexible joints can reduce the transmission of vibration.
4. The chilled water pipeline and expansion water tank shall be insulated, and the valve joints shall be reserved with maintenance and operation parts.
Electrical part of power supply
After the unit arrives at the site, the power line needs to be connected to the unit control cabinet. Connect the power line to terminal A, B, C, N, PE, and tighten the terminal again after 24 hours of operation (the shortest time allowed).
Note: The power supply of water pump and cooling tower fan shall be equipped with a separate power supply box. The specification of the power line connected to the control cabinet shall be selected according to the RLA current on the nameplate. The total power supply must be equipped with a certain margin, The recommended value is 1.25~1.3 times of the unit parameters. The current carrying capacity of power supply cable (wire) shall be slightly greater than the maximum operating current of the unit, and the influence of working environment shall be considered. The electric cabinet is equipped with ground wire connection and automatic circuit breaking measures, which must be provided for the power supply provided by the user. The large current unit shall be powered by dual power supply, but the wire diameters of the two power supply must be the same and belong to the same brand.
The maximum allowable phase voltage imbalance is 2%, and the phase current imbalance is 10%. If the phase voltage imbalance is greater than 2%, the machine must not be started.
For example: Nominal voltage is 3N~, AC380V, 50Hz, measured UAB=376V UAC=379V、UBC=385V。 The average voltage=(376+379+385)/3=380V
Determine the deviation value from the average voltage:
△UAB=380-376=4V、△UAC=380-379=1V、△UBC=385-380=5V。 The maximum deviation is 5V. 5/380=1.3%, the maximum phase voltage imbalance is 1.3%. The damage caused by startup operation when the phase voltage imbalance is greater than 2% shall be regarded as improper operation.
On site commissioning steps of water-cooled chiller
Step 1: After arriving at the site, check whether the appearance of the host is bumping or not, and observe whether the indication of the high and low pressure gauges is normal and whether there is fluorine leakage.
Step 2: Check whether the power supply meets the three-phase five wire system and the unit load. Check whether the wiring posts in the electric box are fastened and whether the electronic control elements are damaged. Use an insulation resistance megger to measure the resistance between each phase and the ground. The correct value of the resistance between the three-phase line and the ground should be 5 megohm.
Step 3: Connect the water flow switch control line, short circuit the unused input interlocking wiring at the terminal, and it is strictly prohibited to short circuit the used protective contacts and terminals. Cooling pump, freezing pump, cooling tower fan control and interlock wiring.
Step 4: After confirming that the wiring is correct, power on and observe the phase sequence and voltage value. If the phase error light is on, adjust the phase sequence; If the voltage is abnormal (380v ± 10%), Party A is required to adjust the voltage. Power on for preheating after the power supply is normal.
Step 5: observe whether the parameters of cooling water pump, chilled water pump, cooling tower and pipe diameter match the main engine; Whether the host and the end match. Whether the cooling water and chilled water systems are equipped with automatic water replenishing devices, filtering devices and water treatment equipment. A filter larger than 40 meshes shall be installed at the water inlet of condenser and evaporator.
Step 6: confirm whether the water system has been cleaned. If it has been cleaned, jog the pump motor and check the positive and negative rotation of the pump motor. In case of inversion, adjust the phase sequence. After the phase sequence is correct, start the cooling pump, observe the pressure of water inlet and outlet before and after the water pump and the condenser. During operation, the water pump deflates. After the operation is normal, start the chilled water pump. Except for the venting of the water pump, the whole system of chilled water should carefully deflate until it is completely discharged. Clean the water filter after the cooling water system and chilled water system operate for 1 hour.
Step 7: Start the cooling water pump and observe the water flow switch status on the touch screen. The correct status is off. Then start the cooling water pump. The correct value of the water flow switch status on the touch screen is on. If the status is off, the water system will bleed until the status value of the water flow switch is turned on. Turn off any one of the pumps, and the water flow switch status should be off. If the status is incorrect, check the flow switch to ensure that it is installed correctly and the feedback is correct (the flow switch should be connected to the normally open point). (Note: For example, for the unit receiving fluorine before leaving the factory, the 220v voltage is supplied to the liquid supply valve after confirming that the water pump has been running, and the liquid supply valve is opened to make the balance pressure normal)
Step 8: observe the Y-Δ delay relay, the correct value is 3.5 seconds, simulate the operation, and start the loading sequence: 25% solenoid valve - liquid supply valve, compressor (simultaneously) - 50% solenoid valve - 75% solenoid valve - 100% solenoid valve. Observe the Y-Δ startup delay time, and adjust it if it is too long or too short. Shutdown process: 100% solenoid valve - 25% solenoid valve - liquid supply valve, compressor (at the same time) stop.
Step 9: Make sure that the water system (cooling and freezing) operates normally. After the simulation operation is normal, the unit shall be preheated for at least 8 hours. Start the host formally. When starting the press, attention must be paid to the pointer of the high and low pressure gauge. At the moment of starting, the pointer of the high pressure gauge rotates clockwise (increases), and the pointer of the low pressure gauge rotates counterclockwise (decreases). On the contrary, emergency stop and check the phase sequence and press wiring. If the phase sequence is correct, use a clamp ammeter to measure the running current, which will gradually rise under normal conditions, and the current value will not be greater than the value marked on the nameplate of the compressor. Otherwise, stop the machine to find out the cause.
Step 10: After the main engine is started (the high and low pressure gauges indicate correctly), first listen to the sound of the press to see if there is any abnormal sound. If there is any abnormal sound, stop the machine in an emergency and find out the cause. After the startup is normal, the exhaust temperature shall rise to above 50 ℃ within 5 minutes under 100% load. If the exhaust temperature cannot rise in time, wet compression will occur, and corresponding measures must be taken (to adjust the temperature of cooling water) to improve the operating conditions and other measures to ensure the normal operation of the main engine.
