(11) Response time
Response time refers to the sudden change in load current, the regulator's output voltage from the beginning of the change to reach a new stable value of a period of adjustment time. In the DC regulator, it is used in the rectangular wave load current when the output voltage waveform to express this characteristic, known as excessive special.
(12) Distortion
Distortion is unique to AC voltage regulators. It means that the output waveform is not a positive waveform, resulting in waveform distortion, called distortion.
(13) Noise
According to the 30Hz - 18kHZ audible frequency regulations, this switching power supply conversion frequency is not a problem, but the power supply with a fan should be specified as needed.
(14)Input noise
In order to keep the switching power supply work in a normal state, according to the rated input conditions, according to the allowable input and superimposed on the industrial frequency of the pulse-like voltage (0 - peak) to develop input noise indicators. General external pulse width of 100-800us, external voltage 1000V.
(15) Surge
This is the input voltage, more than 1 minute interval in accordance with the specified number of times a surge voltage, in order to avoid the occurrence of insulation damage, flashover, arc and other abnormal phenomena. Communication equipment and other provisions of the value of thousands of volts, generally 1200V.
(16) Electrostatic noise
Refers to the rated input conditions, added to any part of the power supply frame, the full output circuit can maintain normal operating conditions of a repeated pulse-like static electricity. Generally guaranteed within 5-10KV.
(17) Stability
Allow the use of conditions, the maximum relative change in output voltage △ Uo / Uo.
(18)Electrical safety requirements (GB 4943-90)
1. Safety requirements of power supply structure
▆Space requirements
UL, CSA, VDE safety standards emphasize the distance between the charged parts and the charged parts and non-charged metal parts of the surface, space requirements. UL, CSA requirements: inter-pole voltage greater than or equal to 250VAC between high-voltage conductors, as well as high-voltage conductors and non-charged metal parts of the (this does not include the conductor between the), regardless of whether between the surface or in the space, there should be 0.1 inches of distance; VDE requirements between AC lines; VDE requirements for the AC line between the relative changes of △ Uo/Uo. distance; VDE requires 3mm of creepage or 2mm of clear space between AC wires; IEC requires 3mm of clear space between AC wires and 4mm of clear space between AC wires and grounded conductors. In addition, VDE and IEC require that there should be at least 8mm space between the output and input of the power supply.
▆ Dielectric test method (playing high voltage: between input and output, input and ground, and input AC level)
▆ Leakage current measurement
Leakage current is the current flowing through the input side ground, in the switching power supply is mainly through the static noise filter bypass capacitor leakage current. UL, CSA are required to expose the non-electrically charged metal parts should be connected to the earth, leakage current measurement is through these parts and the earth connected to a 1.5K ohms resistor, the leakage current should not be greater than 5 mA. VDE allows: 1.5K ohms resistor and 150nP capacitor in parallel. VDE allows: Parallel connection of a 1.5K ohm resistor to a 150nP capacitor. With 1.06 times the rated operating voltage applied, the leakage current should be no more than 3.5 mA for data processing equipment. Generally, it is about 1mA.
▆ Insulation Resistance Test
VDE requirements: input and low-voltage output circuits should be between the resistance of 7M ohms, between the accessible metal parts and the input, should be 2M ohms of resistance or 500V DC voltage for 1 minute.
▆ Printed Circuit Board Requirements
UL recognized 94V-2 material or better is required. 2.
2. Safety requirements for power transformer structure
▆ Transformer insulation
Transformer windings used in the copper wire should be enameled wire, other metal parts should be coated with porcelain, paint and other insulating substances.
▅Transformer dielectric strength
There should be no insulation layer rupture and flying arc phenomenon in the experiment.
▆ transformer insulation resistance
Transformer winding insulation resistance of at least 10M ohms, in the winding and core, skeleton, shielding layer between the application of 500 volts DC voltage for 1 minute, there should be no breakdown, flying arc phenomenon.
▆ Transformer humidity resistance
Transformer must be placed in a humid environment, immediately after the insulation resistance and dielectric strength test, and meet the requirements. Humid environment is generally: relative humidity of 92% (tolerance of 2%), the temperature stabilized between 20 to 30 degrees Celsius, allowing a tolerance of 1%, need to be placed inside at least 48 hours after the immediate conduct of the above experiments. The temperature of the transformer itself should not be more than 4 degrees Celsius higher than that tested before entering the humid environment.
▆ VDE requirements for temperature characterization of transformers
▆ UL, CSA requirements for transformer temperature characteristics.
Note: IEC - International ElectrotechnICal Commission
VDE--Verbandes Deutcher ElectrotechnICer
UL--Underwriters' Laboratories
CSA--Canadian Standards Association
FCC--Federal CommunICations Commission
(19) Radio Nuisance (tested according to GB 9254-1998)
1. Limit value of disturbing voltage at power supply terminals
2. Radiated nuisance limits
(20) Electromagnetic compatibility test
Electromagnetic compatibility test (electromagnetIC compatiblity EMC)
Electromagnetic compatibility refers to the equipment or system in the common electromagnetic environment can work normally and does not constitute any thing in the environment can not withstand the electromagnetic interference ability.
Electromagnetic interference waves generally have two propagation paths and are evaluated according to each path. One is to propagate to the power line with a long frequency band to the transmitting area to interfere with the pathway, generally below 30MHz. This wave length frequency in the length of the power line attached to the electronic equipment is less than 1 wavelength, the amount of radiation into space is also very small, which can be grasped by the voltage that occurs on the power line, and then the size of the interference can be adequately assessed, this noise is called the conduction noise.
When the frequency reaches 30MHz or more, the wavelength becomes shorter. In this case, if only the voltage of the noise source occurring on the power supply line is evaluated, it does not correspond to the actual interference. Therefore, a method of evaluating the size of the noise by directly measuring the interference wave propagating into space has been adopted, and this noise is called radiated noise. The method of measuring radiated noise includes the above method of directly measuring the interference wave propagating in space by the electric field strength, and the method of measuring the power leaking into the power supply line.
Electromagnetic compatibility tests include the following tests:
① Magnetic field sensitivity: (Immunity) The level of unwanted response of equipment, subsystems or systems exposed to electromagnetic radiation. The smaller the sensitivity level, the higher the sensitivity and the lower the immunity. Fixed frequency, peak-to-peak magnetic field
② Electrostatic Discharge Sensitivity: Charge transfer caused by objects with different electrostatic potentials being in close proximity to each other or in direct contact. 300PF capacitor charged to -15,000V and discharged through a 500 ohm resistor. Can be out of tolerance, but normal after discharge. Data transfer, storage, can not be lost
③ Power transient sensitivity: including spike signal sensitivity (0.5us 10us 2 times), voltage transient sensitivity (10%-30%, 30S recovery), frequency transient sensitivity (5%-10%, 30S recovery).
④ Radiation sensitivity: the measure of the radiation interference field that causes equipment degradation. (14K-1GHz, electric field strength is 1V/M)
⑤ Conducted sensitivity: Measurement of the interfering signal or voltage on the power, control, or signal line when causing an undesired response or degradation of the equipment's performance. (30Hz-50KHZ 3V , 50K-400M 1V)
⑥ Non-working state magnetic field interference: packing box 4.6m magnetic flux density less than 0.525uT, 0.9m 0.525Ut.
⑦ Work state magnetic field interference: up, down, left, right AC magnetic flux density less than 0.5mT.
⑧ Conducted interference: interference propagated along the conductor. 10KHz-30MHz 60 (48) dBuV.
⑨ radiation interference: electromagnetic interference propagated through space in the form of electromagnetic waves. 10KHz-1000MHz 30 shielded room 60 (54) uV/m.
(21)Environmental experiments
Environmental testing is to expose products or materials to natural or artificial environments, so as to evaluate their performance in the storage, transportation and use conditions that may actually encounter. Including low temperature, high temperature, constant humidity and heat, alternating humidity and heat, impulse (shock and collision), vibration, constant acceleration, storage, mold, corrosive atmospheres (eg, salt spray), sand and dust, air pressure (high pressure or low pressure), temperature change, flammability, sealing, water, radiation (solar or nuclear), soldering, termination strength, noise (micro-playing 65DB) and so on.
Contact:
Phone: +86-158-7657-0341
E-mail: market@jmhvpower.com
Whatsapp:+86-158-7657-0341
Add: Guangdong Province, China TianHe District, GuangZhou Num 899
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