LED indicators for power and reliability testing of several standardized Detailed

1, describes the impact of the input voltage output voltage of several indicators of the form

⑴ regulator factor
① absolute voltage coefficient K

That the load is constant, regulated power supply output DC voltage variation △ Uo and input voltage variation △ Ui ratio, that is, K = △ Uo / △ Ui.

② Relative regulators coefficient S

That the load is constant, regulated output DC voltage Uo of the relative variation △ Uo / Uo Ui of the input voltage relative change △ Ui / Ui ratio, that is, S = △ Uo / Uo / △ Ui / Ui.

⑵ grid regulation

The input voltage changes by the rating of + / -10%, the power supply output voltage relative variation, sometimes with the absolute value of that.

⑶ voltage stability

Rated load current remains within the scope of any value, the input voltage changes within the limits prescribed by the relative change in output voltage due to △ Uo / Uo (percentile), known as the regulator of the voltage stability.

2, the load on the output voltage of the impact of several indicators in the form

⑴ load regulation (also known as the current regulation)

At rated voltage, the load current from zero to maximum, the maximum output voltage relative change, often expressed as a percentage, sometimes expressed in absolute amount of change.

⑵ output resistance (also known as resistance or equivalent resistance)

At rated voltage, due to changes in load current causes the output voltage change △ IL △ Uo, the output resistance Ro = | △ Uo / △ IL | Ω.

3, the ripple voltage of several indicators of the form

⑴ maximum ripple voltage

At rated output voltage and load current, output voltage ripple (including noise) of the absolute value, usually expressed in peak or RMS.

⑵ ripple factor Y (%)

At rated load current, the output ripple voltage and output DC voltage rms Uo Urms ratio, that is, Y = Umrs / Uo x100%.

⑶ ripple voltage rejection ratio

Specified ripple frequency (eg 50HZ), the input voltage ripple voltage Ui ~ and in the output voltage ripple voltage Uo ~ ratio, namely: the ripple voltage rejection ratio = Ui ~ / Uo ~.

4, electrical safety requirements

⑴ power structure of the safety requirements

① space requirements

UL, CSA, VDE safety specifications highlighted in the live parts and between live parts and conductive parts of the surface between the space of distance requirements. UL, CSA requirements: greater than or equal voltage between 250VAC high voltage conductors, and between high-voltage conductors and conductive metal parts (not included here, between the wires), both on the surface or in the space between, should have a 0.1-inch distance; VDE requires AC line creep between 3mm or 2mm clearance gap; IEC requirements: AC line 3mm of clearance between space and ground conductors in the AC line and the clearance between the 4mm gap. In addition, VDE, IEC power required between the output and input, at least 8mm of space spacing.

② experimental dielectric test methods

Playing high-pressure: input and output, input and ground, between the input AC two.

③ leakage current measurement

Leakage current is the current flowing through the input side of the ground, mainly in switching power supply bypass capacitor through a noise filter leakage current. UL, CSA does not require exposed metal parts should be charged with connecting the earth leakage current is measured by the indirect part of the earth a 1.5kΩ resistor, the leakage current should be allowed not more than 5 mm mA.VDE with a 1.5kΩ resistor and capacitor connected with 150nPF and used to impose 1.06 times the rated voltage, the data processing equipment, the leakage current should be less than 3.5mA, typically 1mA or so.

④ insulation resistance test

VDE requirements: low-voltage input and output circuits should 7MΩ resistance, can come into contact with the metal parts and between the inputs, or increase the resistance should 2MΩ 500V DC voltage continuous 1min.

⑤ printed circuit board

Require the use of UL Listed 94V-2 material or better material.

⑵ the structure of the safety requirements of power transformers

① transformer insulation

Transformer windings should be enameled copper, other metal parts should be coated with porcelain, lacquer and other insulating material.

② the dielectric strength of transformer

In the experiment should not appear in insulation breakdown and arcing phenomena.

③ transformer insulation resistance

Transformer winding insulation resistance between the at least 10MΩ, in the winding and core, frame, shielding layer 500 volts DC applied voltage, continuous 1min, there should not breakdown, arcing phenomena.

④ transformer humidity resistance

Transformer must be placed in the humid environment immediately after the insulation resistance and dielectric strength test, and meet the requirements. Humid environment generally: the relative humidity of 92% (tolerance 2%), temperature stabilized at 20 ℃ to 30 ℃, 1% allowable error, the need for at least 48h, including immediately after the experiment. At this point temperature of the transformer itself into a more humid environment should not be higher than before the test 4 ℃.

⑤ VDE requirements on temperature characteristics of the transformer.

⑥ UL, CSA requirements on temperature characteristics of the transformer.

5, electromagnetic compatibility testing

Electromagnetic compatibility refers to the equipment or system in a common electromagnetic environment can not work anything in the environment can not constitute the ability to withstand electromagnetic interference.

There are two kinds of electromagnetic interference wave transmission, according to the evaluation of the various channels.One is based on longer-wavelength band to the power line communication, to the launching area to disrupt the way, usually in the 30MHz or less. This longer-wavelength frequency electronic devices attached to the length of the power cord is not even a range of wavelengths, the radiation to the small amount of space, which can occur in the control line voltage LED power supply, and thus can be full assessment of the size of interference, this noise is called the conduction noise.

When the frequency of 30MHz or more, shorter wavelengths will follow. At this time only occurs if the noise source voltage power line to evaluate the interference with the actual match. Therefore, based on a direct determination of the interference of wave propagation to space the size of the noise evaluation method, called the noise radiated noise. Radiated noise measurement method according to electric field strength of the interference of wave propagation space measurement method and the direct determination of leakage power to the power line method.

Electromagnetic compatibility tests, including the contents of the following tests:

① magnetic field sensitivity

(Immunity) equipment, subsystems or systems exposed to electromagnetic radiation do not want to respond to some degree. The smaller the sensitivity level, the higher the sensitivity, immunity worse. Including fixed frequency, peak magnetic field testing.

② electrostatic discharge sensitivity

Objects with different electrostatic potentials caused by direct contact or close to each other the charge transfer. 300PF capacitor is charged to-15000V, discharged through a 500Ω resistor. Can be ultra-poor, but after put to normal. Testing, data transfer, storage can not be lost.

③ LED power transient sensitivity

Including spike sensitivity (0.5μs, 10μs 2-fold), transient voltage sensitivity (10% -30%, 30S recovery), frequency transient sensitivity (5% -10%, 30S recovery).

④ Radiation Sensitivity

The device degradation caused by the radiation of the interference field of measurement. (14kHz-1GHz, the electric field strength of 1V / M).

⑤ conduction sensitivity

When the cause equipment to respond to or do not want to cause some performance degradation when in power, control or interfere with the signal or the signal line voltage measurement.(30Hz-50kHz/3V, 50kHz -400MHz/1V).

⑥ non-working state magnetic interference

Box 4.6m, magnetic flux density is less than 0.525μT; 0.9m, 0.525μT.

⑦ working state magnetic interference

Up, down, left and right AC magnetic flux density is less than 0.5mT.

⑧ conducted interference along the conductor transmission interference. 10kHz-30MHz, 60 (48) dBμV.

⑨ Radiation interference: the form of electromagnetic wave propagation through space of electromagnetic interference.10kHz-1000MHz, 30 shielded room 60 (54) μV / m.
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