When using a variable frequency power supply,we always suggest to customers that the variable frequency power supply is an electronic product.During the startup and operation process,in addition to the environment,it is also necessary to pay attention to whether the environment in which the variable frequency power supply is placed is suitable.Variable frequency power supplies,as electronic products,generate heat during use.Therefore,the issue of machine heat dissipation becomes quite important.If they are not placed in a ventilated and heat dissipating environment,the machine will be unable to expel hot air,causing the internal temperature of the machine to rise by one degree.Just like humans,if their body temperature rises,they will experience fever.So,let me share with you the precautions for using switch mode power supplies:
　　1.Output Calculation
　　The input voltage of a switching power supply can be 220V or 110V,and the input voltage level should be selected reasonably according to the circuit design.Otherwise,it will cause damage to the switching power supply.
　　Due to the high efficiency of switch mode power supplies,which can generally reach over 80%,the selection of output current should accurately measure or calculate the maximum absorbed current of the electrical equipment to ensure that the selected switch mode power supply has a high performance to price ratio.The usual output calculation formula is:
　　Is=KIf
　　In the formula:Is-rated output current of the switching power supply;
　　If-the maximum absorbed current of the electrical equipment;
　　K-margin coefficient,generally taken as 1.5-1.8;
　　2.Grounding
　　The metal casing of the switching power supply is generally connected to the(FG)and should be reliably grounded to ensure safety.The casing should not be mistakenly connected to the neutral line.Switching power supplies generate more interference than linear power supplies.For electrical equipment sensitive to common mode interference,grounding and shielding measures should be taken.According to EMC limitations such as ICE1000,EN61000,FCC,etc.,switching power supplies all adopt EMC electromagnetic compatibility measures.Therefore,switching power supplies generally should be equipped with EMC electromagnetic compatibility filters.For example,the HA series switching power supply of Lide Huafu Technology can only meet the above electromagnetic compatibility requirements by grounding its FG terminal or connecting it to the user's casing.
　　3.Protection circuit
　　Before powering on the switch power supply after installation,please double check and verify the connections on each wiring terminal to ensure that the input and output,AC and DC,single-phase and multiphase,positive and negative,voltage and current values are correct before powering on the operation.In the design of switch mode power supplies,they must have protection functions such as overcurrent,overheating,and short circuit.Therefore,a switch mode power supply module with complete protection functions should be preferred in the design,and the technical parameters of its protection circuit should match the working characteristics of the electrical equipment to avoid damage to the electrical equipment or switch mode power supply.
　　4.Wiring method
　　For high-power switch mode power supplies,there are generally two or more"+"output terminals and"-"output terminals on the ground.In fact,they belong to the same output electrode and are only connected together internally for the convenience of user wiring.
　　L:Connect to 220V AC live wire;
　　N:Connect to 220V AC neutral line;
　　FG:Grounding;
　　G:DC output ground;
　　+5V:Port for outputting+5V points;
　　ADJ:It adjusts the output voltage within a certain range.The rated voltage output on a switching power supply is originally fixed at the factory,which is the nominal rated output voltage.Setting this potentiometer allows users to adjust the output voltage within a small range based on actual usage,and generally does not require adjustment.
　　In order to achieve sufficient heat dissipation,a general switch power supply should be installed in a location with good air convection conditions,or installed on the chassis shell to transfer heat outdoors through the shell.
　　6.Before leaving the factory,the switching power supply should be tested with a resistive load.If it needs to be used for capacitive or inductive loads,it should be specified in the purchase contract in advance;
　　7.For dual channel switching power supplies with symmetrical output loads,priority should be given to using symmetrical output power supplies;
　　8.For users with grounded switch mode power supply FG,it is normal to feel a tingling sensation when touching the casing or output.When floating to ground,FG has an AC output of about 110V to the ground,which is determined by the internal structure of the power supply.
　　9.Before leaving the factory,switch mode power supplies should be 100%filled with negative voltage during aging.Generally,the power usage rate should be controlled within 80%or lower,which can greatly improve the service life of the power supply.Generally,the capacitor life is reduced by half for every 10℃increase in power supply temperature;
　　10.The ripple and noise of a switching power supply are the AC components superimposed on the DC output voltage,generally expressed in millivolt peak values;
　　11.For all switching power supplies,when there is a sudden change in load,there will be a certain response time.During this sudden change,the output voltage of the power supply will have a brief overshoot process,and then return to the normal output state,which is dynamic response;
　　12.Once there is a malfunction in the switching power supply,the factory should be notified as soon as possible.The factory will be responsible for free maintenance or technical guidance,except for those who dismantle the power supply without authorization.