Switching power supply test specification
Source: China Instrumentation Information Network Time: 2007-11-26 Font: [ Large Medium Small ] Contributor
Part I: power supply indicators of concepts, definitions
I. Describe the input voltage affects the output voltage in the form of several indicators.
1. Absolute voltage regulation factor.
A. Absolute voltage stabilization coefficient: indicates that when the load is unchanged, the regulated power supply output DC variation △ U0 and input grid variation △ Ui ratio. Both:
K=△U0/△Ui.
B. Relative voltage stabilization coefficient: When the load is unchanged, the voltage regulator output DC voltage Uo relative change △Uo and output grid Ui relative change △Ui ratio. Urgency:
S=△Uo/Uo / △Ui/Ui
2. Grid Adjustment Rate.
It indicates the relative amount of change in the output voltage of the regulated power supply when the input grid voltage is changed by +-10% from the rated value, sometimes expressed in absolute terms.
3. Voltage Stability.
Load current is maintained as any value within the rated range, the relative change in output voltage caused by changes in the input voltage within the specified range △ Uo / Uo (percent), known as the voltage stability of the regulator.
II. Load on the output voltage impact of several forms of indicators.
1. Load regulation rate (also called current regulation rate).
In the rated grid voltage, the load current from zero to the maximum change, the maximum relative change in output voltage, commonly used as a percentage, sometimes also expressed in absolute change.
2. Output resistance (also called equivalent internal resistance or internal resistance).
In the rated grid voltage, due to the load current change △ IL caused by the output voltage change △ Uo, then the output resistance is
Ro = | △ Uo / △ IL | ohm. Source:
III. Several indicator forms of ripple voltage.
1. Maximum ripple voltage.
The magnitude of the absolute value of the ripple (including noise) of the output voltage, usually expressed as peak-to-peak or RMS, at the rated output voltage and load current.
2. Ripple coefficient Y (%).
Under the rated load current, the ratio of the RMS value of the output ripple voltage, Urms, to the output DC voltage, Uo, is both
y=Umrs/Uo x100%
3. Ripple voltage rejection ratio.
At a specified ripple frequency (e.g., 50 HZ), the ratio of the ripple voltage Ui~ in the output voltage to the ripple voltage Uo~ in the output voltage, i.e.
Ripple Voltage Rejection Ratio = Ui~/Uo~ .
Here's a disclaimer: noise is different from ripple. Ripple is a component that appears between the output terminals synchronized with the input frequency and switching frequency, expressed as a peak-to-peak (peak to peak) value, generally less than 0.5% of the output voltage; noise is a high-frequency component other than the ripple that appears between the output terminals, also expressed as a peak-to-peak (peak to peak) value, generally about 1% of the output voltage. Ripple noise is the synthesis of the two, with peak-to-peak (peak to peak) value, generally in the output voltage below 2%.
IV. Inrush current. Inrush current is the input voltage according to the specified time interval on or off, the input current to reach a steady state before the maximum instantaneous current. Generally 20A - 30A.
V. Overcurrent protection. Is a power load protection function to avoid the occurrence of overload output current including short circuit on the output terminals on the power supply and load damage. The given value of overcurrent is generally 110% - 130% of the rated current. Source:Transmission and distribution equipment network
VI. Over-voltage protection. Is a function of load protection against excessive voltage between terminals. Generally specified as 130% - 150% of the output voltage.
VII. Output undervoltage protection. When the output voltage is below the standard value, the detection of the output voltage drop or to protect the load and prevent misuse and stop the power supply and send an alarm signal, more for the output voltage of 80% - 30% or so.
VIII. Overheating protection. Abnormalities within the power supply or improper use of the power supply temperature rise exceeds the standard to stop the power supply and send an alarm signal.
9. Temperature drift and temperature coefficient.
Temperature drift: changes in ambient temperature affects the parameters of the components change, thus causing the regulator output voltage change. Commonly used temperature coefficient indicates the size of the temperature drift.
Absolute temperature coefficient: temperature change of 1 degree Celsius caused by the output voltage value of the change △ UoT, the unit is V / ℃ or millivolt per degree Celsius.
Relative temperature coefficient: temperature change of 1 degree Celsius caused by the relative change in output voltage △ UoT/Uo, the unit is V/°C.
X. Drift.
Voltage regulator in the input voltage, load current and ambient temperature to maintain a certain situation, the stability of the component parameters will also cause changes in the output voltage, slow changes called drift, fast changes called noise, between the two is called ups and downs.
There are two ways to represent drift:
1. The change in output voltage value within a specified time △Uot.
2. The relative change in output voltage within a specified time △Uot/Uo.
The time for examining drift can be set at 1 minute, 10 minutes, 1 hour, 8 hours or longer. Source:
Temperature coefficient and temperature drift are only available for higher precision regulators.
XI. Response time.
It is a period of adjustment time for the output voltage of a voltage regulator to arrive at a new stabilized value from the beginning of the change when the load current changes suddenly.
In DC regulators, this characteristic is expressed in terms of the output voltage waveform at rectangular-wave load current, called the excess characteristic.
XII. Distortion.
This is unique to AC regulators. Is the output waveform is not a positive waveform, resulting in waveform distortion, called distortion.
Thirteen. 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.
XIV. 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 outside and superimposed on the industrial frequency of 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, at intervals of more than 1 minute in accordance with the specified number of times to add a surge voltage, in order to avoid the occurrence of insulation damage, flashover, arcing and other abnormal phenomena. Communication equipment and other provisions of the value of thousands of volts, generally 1200V.
Sixteen. 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 5 - 10KV or less.
Source:www.tede.cn
XVII. Stability.
Allowable conditions of use, the maximum relative change in output voltage △ Uo / Uo .
XVIII. Electrical safety requirements (GB 4943-90).
1. Safety requirements for power supply structure.
1) space requirements. UL, CSA, VDE safety regulations emphasize the distance requirements between the charged parts and between the charged parts and non-charged metal parts of the surface, space. UL, CSA requirements: inter-pole voltage greater than or equal to 250VAC between the high-voltage conductors, as well as high-voltage conductors and non-charged metal parts of the (this does not include the conductor between the wire), regardless of whether between the surface of the or in space, there should be 0.1 inches of 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, IEC requirements in the power supply between the output and input, at least 8mm space spacing.
2) Dielectric experimental test methods (playing high voltage: between input and output, input and ground, input AC two levels).
3) Leakage current measurement. Leakage current is the current flowing through the input side of the ground, in the switching power supply is mainly through the static noise filter bypass capacitor leakage current. UL, CSA are required to exposed non-electrically charged metal parts should be connected to the earth, the leakage current measurement is done by connecting these parts to the earth between a 1.5K ohm resistor, the leakage current should be no greater than 5 mA. VDE allows: 1.5K ohm resistor in parallel with the 150nP capacitor in parallel. and applying 1.06 times the rated operating voltage, the leakage current should be no greater than 3.5 mA for data processing equipment. Usually it is about 1 mA. Please visit:Power Transmission and Distribution Equipment Website for more information
4) Insulation resistance test.VDE requirement: there should be 7M ohm resistance between the input and low voltage output circuits, and 2M ohm resistance between the accessible metal parts and the inputs or apply 500V DC voltage for 1 minute.
5) Printed circuit board requirements. UL recognized 94V-2 material or better is required.
2. Safety requirements for power transformer structure.
1) Transformer insulation. The copper wire used for the windings of the transformer shall be enameled wire, and other metal parts shall be coated with insulating substances such as porcelain and lacquer.
2) transformer dielectric strength. In the experiment there should be no insulation rupture and flying arc phenomenon.
3) insulation resistance of the transformer. 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.
4) 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: 92% relative humidity (tolerance of 2%), the temperature stabilized between 20 to 30 degrees Celsius, the error allows 1%, need to be placed inside at least 48 hours, immediately after the above experiments. At this time, the transformer's own temperature should not be 4 degrees Celsius higher than the test before entering the humid environment.
5) VDE requirements for transformer temperature characteristics.
6) UL, CSA requirements for transformer temperature characteristics.
Note: IEC--International Electrotechnical Commission
VDE--Verbandes Deutcher Electrotechnicer Source:www.tede.cn
UL - Underwriters' Laboratories
CSA - Canadian Standards Association
FCC - Federal Communications Commission
19. Radio Harassment (tested according to GB 9254-1998).
1. Power terminal nuisance voltage limit.
2. Radiated nuisance limits.
Twenty. Environmental test.
Environmental testing is the exposure of products or materials to natural or artificial environments, so as to evaluate their performance under the conditions of storage, transportation and use that may actually be encountered.
(1) Low temperature
(2) High temperature
(3) Constant humidity and heat
(4) Alternating humidity and heat
(5) Impingement (impacts and crashes)
(6) Vibration
(7) Constant acceleration
(8) Storage
(9) Mould growth
(10) Corrosive atmospheres (e.g., salt spray)
(11) Sand dust
(12) Air pressure (high or low pressure)
(13) Temperature change
(14) Flammability
(15) Sealing
(16) Water
(17) Radiation (solar or nuclear)
(18) Soldering
(19) Connection strength
(20) Noise: Slightly hitting 65DB
XXI. Electromagnetic compatibility test.
Electromagnetic compatibility test (electromagnetic compatiblity EMC)
Electromagnetic compatibility refers to the equipment or system in the **** the same electromagnetic environment can work normally and does not constitute an intolerable electromagnetic interference to any thing in the environment.
Electromagnetic interference waves generally have two ways of propagation, according to the evaluation of each pathway. One is a long frequency band to the power line propagation, to the transmitting area to interfere with the pathway, generally below 30MHZ. This wavelength frequency in the attached to the length of the power line of electronic equipment is not less than 1 wavelength, the amount of radiation into space is also very small, which can be grasped by the voltage occurring on the power line, and then can be adequately assessed the size of the interference, this noise is called the conduction noise. Source:Transmission and distribution equipment network
When the frequency reaches 30MHZ or more, the wavelength will also become shorter. At this point, if only the voltage of the noise source occurring in the power line is evaluated, it does not match the actual interference. Therefore, the method of evaluating the size of noise by directly measuring the interference wave propagating into space is adopted, and the 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 line.
Electromagnetic compatibility tests include the following tests:
① Magnetic field sensitivity: (antidisturbance) equipment, subsystems or systems exposed to electromagnetic radiation under the degree of unwanted response. 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: objects with different electrostatic potentials close to each other or caused by direct contact with the charge transfer. 300PF capacitor charged to -15000V, discharged through a 500-ohm resistor. Can be super poor, but after discharge to normal. 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: a measure of the radiation interference field that causes equipment degradation. (14K-1GHZ, electric field strength of 1V/M)
⑤ Conductivity sensitivity: when caused by the unwanted response of the equipment or cause its performance degradation, the measure of the interference signal or voltage in the power, control or signal lines. (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. Source:
⑦ Working state magnetic field interference: up, down, left, right AC magnetic flux density less than 0.5mT.
⑧ Conducted interference: Along the conductor propagation of interference. 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.
Part II Test Methods
I. Withstanding Voltage
(HI.POT,ELECTRIC STRENGTH ,DIELECTRIC VOLTAGE WITHSTAND)KV
1.1 Definition: Between the specified terminals, such as: I/P-O/P, I/P-FG, O/P-FG, can withstand the rms of the AC, the leakage current can be allowed to be 10 mA, time 1 minute. Leakage current is generally allowed to be 10 milliamps, time 1 minute.
1.2 Test conditions: Ta: 25 degrees Celsius; RH: Room humidity.
1.3 Test Circuit:
1.4 Description:
1.4.1 The main purpose of voltage withstand test is to prevent the electrical damage, through the input of high voltage, affecting the safety of users.
1.4.2 During the test, the voltage must be adjusted upward from 0V, and adjusted to the highest point within 1 minute.
1.4.2 When discharging, you must pay attention to the tester's Timer setting, and adjust the voltage back to 0V before OFF.
1.4.3 When testing for safety certification, the transformer needs to be tested separately, indoors, at a temperature of 25 degrees Celsius, RH: 95 degrees Celsius, 48HR, and then test the transformer's primary/secondary and primary/CORE.
1.4.4 The test time is 1 second. Production line test time is 1 second.
II. Ripple noise (ripple noise voltage)
(Ripple & Noise)%, mv
2.1 Definition:
DC output voltage overlap on the AC voltage component of the maximum value (P-P) or RMS value. Please visit: Transmission and distribution equipment network to view more information
2.2 test conditions:
I/P: Nominal
O/P : Full Load
Ta : 25 ℃
2.3 test circuit:
2.4 test waveforms:
2.5 Description:
2.5.1 The shorter the GND line of the oscilloscope, the better, and the farther away from the PUS the test line should be.
2.5.2 Use a 1:1 Probe.
2.5.3 The BW of the Scope is usually set to 20MHz, but for the current network products to test the ripple noise, it is best to set the BW to the maximum.
2.5.4 Noise and the use of instruments, the environment is very different, so the test must indicate the test location.
2.5.5 Test Ripple Noise to not exceed the original specification value +1% Vo.
3. Leakage Current (Leakage Current)
(Leakage Current) mA
3.1 Definition:
Input a chassis between the current flow (chassis must be connected to earth).
3.2 Test Conditions:
I/P: Vin max.×1.06(TUV)/60Hz
Vin max.(UL1012)/60Hz
O/P: No Load/Full Load
Ta: 25 ℃
3.3 Test Circuit:
3.4 Description:
3.4.1 L, N are to be measured.
3.4.2 UL1012 R-value is 1K5.
TUV R-value is 2K/0. 15uF.
3.4.3 Leakage current specification TUV:3. 5mA,UL1012:5mA.
4. Temperature Test
(Temperature Test)
4.1Definition:
Temperature test refers to the PSU in normal operation, its parts or Case temperature shall not exceed the material specification
Grade or specification value. Source:
4.2 Test Conditions:
I/P: Nominal
O/P: Full Load
Ta : 25°C
4.3 Test Methods:
4.3.1 The Thermo Coupler (TYPE K) will be securely fastened to the object of measurement
(quick drying). p>
(Quick-dry, Tape or soldering method).
4.3.2 The Thermo Coupler is twisted three times at the end and soldered into a ball.
4.3.3 We generally measure with a spot thermometer.
4.4 Test parts:
Heat source and susceptible to heat source parts
For example: input terminals, Fuse, input capacitance, input inductance, filter capacitance, bridge rectification, thermo
sensitive, surge absorber, output capacitance, output capacitance, output inductance, transformer, core,
wire-wound, heatsink, high-power semiconductors, Case, heat source parts under the P.C.B........
4.5 Parts Temperature Limitations:
4.5.1 If the temperature of a part is labeled, the labeled temperature shall be used as the reference.
4.5.2 For other parts with no temperature indication, the temperature shall not exceed the temperature of the P.C.B.
4.5.3 Inductive display individual application for safety regulations, the temperature rise limit 65 ℃ Max (UL1012), 75 ℃
Max (TUV).
V. Input Voltage Regulation
(Line Regulation), %
5.1 Definition:
When the input voltage changes within the rated range, the rate of change of the output voltage.
Vmax-Vnor
Line Regulation(+)=------------------
Vnor
Vnor-Vmin
Line Regulation(-)=------------------ Source:
Vnor
Vmax-Vmin
Line Regulation=----------------
Vnor
Vnor: Input voltage is the normal value, and the output is the output voltage at full load.
Vmax: The maximum output voltage when the input voltage changes.
Vmin: The lowest output voltage when the input voltage changes.
5.2 Test Conditions:
I/P:Min./Nominal/Max
O/P:Full Load
Ta:25℃
5.3 Test Loop:
5.4 Description:
Line Regulation is also direct. The ±maximum
value of Vmax-Vnor and Vmin-Vnor is expressed in mV, together with the Tolerance%.
VI. Load Regulation %
5.1 Definition:
The rate of change of output voltage when the output current varies within the rated range (static).
|Vminl-Vcent|
Line Regulation(+)=------------------×100%
Vcent
|Vcent-VfL|
Line Regulation(-)=------- -----------×100%
Vcent
|VminL-VfL|
Line Regulation(%)=----------------×100%
Vcent
VmilL:Output Voltage at Minimum Load
VfL:Output Voltage at Full Load
Vcent:Output Voltage at Half Load
6.2 Test Condition:
I/P:Nominal
O/P:Min./Half/Full Load
Ta:25℃
6.3 Test Loop:
6.3 Test Circuit:
6.4Load Regulation can also be directly Vmin.L-Vcent and Vcent-Vmax. of the ± maximum source: transmission and distribution equipment network
Value expressed in mV, and then with the Tolerance% said.
The third part of the test report requirements of the project:
For the power supply parts recognized test, the test report requires the provision of test data and conclusions. Incoming inspection can be reduced according to the requirements of the test items, for the test failed products should indicate the failure of the test items.
I. Input characteristics.
1. Operating input voltage and voltage variation range.
2. Input voltage frequency and frequency variation range.
3. Rated input current. It is the current when the input voltage and output current are at rated conditions.
4. Input sag and instantaneous blackout. This is a state of input voltage instantaneous drop or instantaneous disconnection, to be qualified by the rated output voltage and current. Test indicators for voltage and time.
5. Inrush current.
6. Leakage current.
7. Efficiency. Because this indicator is related to heat generation, so the efficiency should be considered when heat dissipation.
8. The test should indicate whether the input is single-phase 2-wire or 3-phase 3-wire.
II. Output characteristics.
1. Rated output voltage.
2. Rated output current.
3. Voltage regulation accuracy.
1) Voltage stability.
2) Current regulation rate.
3) Ripple noise. Including the maximum ripple voltage; maximum ripple noise voltage.
4. The value of the variation of output voltage due to instantaneous current variation.
3. Attachment function requirements.
1. Overcurrent protection.
2. Over-voltage protection.
3. Input undervoltage protection.
Source:www.tede.cn
4. Overheating protection.
5. Insulation resistance. Input terminal and case; input terminal and output terminal; output terminal and case.
6. Insulation voltage. Playing high voltage: input and output, input and ground, input AC between the two levels, according to the national standard for high voltage values.
4. Structure specifications.
1. Shape conditions: such as the presence or absence of the outer casing.
2. Determine the outer dimensions and dimensional tolerances.
3. Installation conditions: mounting location, mounting holes, etc.
4.
4. Cooling conditions: forced or self-cooling and ventilation direction, air volume and aperture size.
5. Interface location and sign.
6. Location of operating parts (output voltage adjustable resistors, switches, indicators) and the location of the prompt text.
7. Weight.
V. Use of environmental conditions.
1. Temperature.
2. Humidity.
3. Vibration and shock resistance.
6. Other conditions.
1. Input noise.
2. Surge.
3. Static noise (required if there is an enclosure).
4.