IEC / EN 61439 Series
Design verification concept; In the current version of the standard in which the construction and testing of electrical panels are defined, it has replaced the concept of TYPE TEST IN ELECTRIC PANELS.
In the subtitles of the concept of design verification there are three methods;
- Verification by testing
- Comparing with a tested reference
- Calculation concepts to be made according to the test data.
Especially for short circuit tests and temperature rise tests, calculation methods and referenced standards are defined in TS EN / IEC 61439-1, and the permitted conditions are detailed.
At the point of verification with test, manufacturers can verify their conformity with the standard by having their products made the necessary tests according to the declared values and conditions of use.
To talk about basic tests according to standard items:
10.2.2) Resistance to corrosion
The purpose of this test is to determine the resistance of the metal parts and sheet metal used by the manufacturer against rusting and to verify their suitability by inspection.
10.2.3) Properties of insulating materials
10.2.3.1) The dry heat test applied in electrical panels made of insulated material includes the purpose of testing the environmental resistance of the electrical panel (or its representative part) at 70 ° C. Cracks that may occur in the sample as a result of the test, the material becoming sticky or oiling are not desired. There should be no adhesion on the fabric pressed on the sample.
10.2.3.2) Representative samples of casing, barrier and other insulating parts are subjected to ball pressure test at 70 ° C or 125 ° C depending on the contact with the current-carrying part. The permit diameter that may occur at the end of the test is binding at the point of making a positive or negative decision about the sample.
10.2.3.3) Another test applied to insulating parts under this title is the glow wire test. The temperatures to be applied during this test are specified in the standard:
960 ° C for sections designed to locate current carrying parts
850 ° C for enclosures intended for mounting in hollow walls
650 ° C for all other parts, including those required to hold the grounding conductor
If there is no flame in the samples entering the glow wire test at the temperature determined according to the design purpose, although the flame is formed, the wire is taken for 30 seconds. If the thin paper or pine board positioned under the sample is not roasted, the materials meet the requirements of the standard.
10.2.4) Resistance to UV radiation
In the test applied to external type panels made of synthetic material or metal material coated with synthetic material, representative samples are subjected to 1000 cycles of test, which will take a total of 500 hours and each will be wet for 25 minutes + 5 minutes. Throughout the test, samples are kept under xenon lamps, care is taken to ensure that the environment is at atmospheric conditions specified in the standard. At the end of the tests, it is subjected to visual inspection. The flexural strength is measured according to the place where the part is taken, and at least 70% retention value is sought in the charpy impact test. The samples should not give a negative result in the glow wire test at the end of the tests.
Charphy impact and flexural controls are also performed.
10.2.5) Lifting
It is the application made in order to control the strength of the lifting devices on the panel, which is brought to 1.25 times the sample weight, based on the manufacturer's declaration. It is important that the loads are properly distributed and positioned when adjusting the weight of the panel. As a result of the vertical and horizontal movement of the panel, which is lifted according to the manufacturer's instructions, a mechanical deterioration, cracking, etc. should not be.
10.2.6) Verification of protection against mechanical impact
Impact tests are applied to the sample in accordance with the IEC 62262 standard based on the manufacturer's declaration.
The number of impacts is adjusted according to the sample size, and the impacts are applied to the sample with hammers in various shapes. Permanent deterioration, possible openings and changes in IP protection degree are recorded as failure.
10.2.7) Marking
Markings other than molding, printing and engraving 15 sec. Wipe with a cotton cloth soaked in water and the same process is done with another cloth soaked in petroleum ether for 15 seconds. is repeated. The marking should be easily readable after the test.
10.3) Degree of protection of assemblies
Tests are carried out according to the manufacturer's declaration. The purpose of these tests is to determine the accuracy of the declared IP rating. Access tests for foreign solid objects + dangerous parts are carried out according to the first digit of the IP rating, while protection tests against water are carried out according to the statement in the second digit. Additional markings for special conditions may be declared by the manufacturer. For the contents of the tests and the equivalence of the declared numbers, the article published within the scope of TS EN / IEC 60529 can be examined.
10.4) Clearances and creepage distances
Air insulation gaps and insulating material surface lengths that may result in malfunction or short circuit are determined and measured one by one. Special rules for bolt heads, small gaps that will not be affected by the degree of pollution and vertical corners are included in Annex F of the standard while measurements are made. These conditions apply to many safety standards.
10.5) Protection against electric shock and integrity of protective circuits
10.5.2) These tests are performed to verify that the sample has an effective protection circuit and ground continuity.
The resistance value between the exposed conductive parts and the grounding point is measured one by one.
Measurements are made using the voltage drop method calculated between two points with at least 10A DC / AC current passing. Under no circumstances should the resistance exceed 100 mOhm.
10.5.3) In addition to this application, the resistance of the earth circuit at the time of short circuit should be verified by one of the methods of test, comparison or calculation. Any of these ways can be used to verify the design.
10.6) Incorporation of switching devices and components
Switchgears, protection equipment, auxiliary and control circuits in the sample are inspected according to the construction rules given in the standard (Article 8.5).
10.7) Internal electrical circuits and connections
The suitability of the main circuit and auxiliary circuits in the sample is examined according to the construction rules given in the standard (Article 8.6).
10.8) Terminals for external conductors
Terminals designed for external connections to the sample (Article 8.8) are inspected according to the construction rules.
10.9) Dielectric properties
In order to verify the insulating ability of the sample, high voltage tests are applied to the sample and it is required that there is no jump, puncture or destructive discharge during the tests.
10.9.2) Power-frequency withstand voltage
High voltage application is made in order to verify the insulation of auxiliary circuits, which are between main circuits and grounded parts, between open contacts of switching devices and designed independent from the main circuit, with other parts. The leakage current value allowed during the tests was limited to 100mA. Voltage values, duration and application methods are explained in detail in the relevant article of the standard. Network frequency test is mostly performed to detect superficial punctures.
10.9.3) Impulse withstand voltage
The same application points are defined with the network frequency withstand voltage.
A sudden rise and then a halving (1.2µs / 50µs) impact withstand voltage is applied to test the insulation against possible jumping by forcing openings in the air.
There should be no destructive discharge during the tests.
10.9.4) Testing of enclosures made of insulating material
Possible outer contact points of the enclosure are energized through the metal leaf. The dielectric test is performed at a level of 50% increased whether there is a jump in the housing structure with circuits inside or outside the housing positioned on this structure.
10.10) Temperature-rise
10.10.2) Verification by testing
This method is based on the measurement results taken from the points described in this process, passing the declared current through the sample. The conductor properties to be connected to the input of the sample, how the outputs will be balanced, the preparation processes of the sample for the test are described in the relevant article of the standard. To mention some of the important points here;
The fact that the conductors do not have a cooling effect, the test ambient temperature, the instantaneous reading of the values and the accurate analysis of the change in the last hour are the parts that affect the results and require precision.
At Switchgear;
- While testing as a whole (10.10.2.3.5) is considered an effective method, when a more detailed analysis is required;
- Testing each output circuit individually at the rated values (here the rated value is determined by the manufacturer) and then monitoring the performance with the diversity factor while all the outputs are active (10.10.2.3.6),
- In addition to the above article, testing and analyzing the main and distribution busbars one by one (10.10.2.3.7) provides manufacturers with very detailed data when they will use calculation and comparison methods and gives the opportunity to verify the performance of the product under different operating conditions.
10.10.3) Verification by comparison
Cross sections, rated values, enclosure properties, power losses, etc. The standard includes the chance to verify according to the test results by comparing the values.
10.10.4) Verification assessment
The results obtained as a result of this study, which is generally based on power losses and enclosure properties, are valid within the scope of the standard.
The critical point here is that this method is defined for single-cell designs with rated current not exceeding 630A and multi-cell designs that do not exceed 1600A. The ways to be followed and the methods referred to are defined under the relevant article in an understandable language.
10.11) Short-circuit withstand strength
The manufacturer's design must be based on the declared short circuit values, the breakers used must be able to open the circuit properly.
Hardware not exceeding 10kA for withstand short circuit value and hardware whose input short circuit value does not exceed 17kA do not need to undergo these tests.
Here, within the scope of design verification; Verification by inspection of design features (10.11.3), comparison with tested design (10.11.4), and testing and verification methods (10.11.5) can be used.
For the main circuit, the effective and peak value of the rated withstand current, the duration of the test, the power factor are important issues, and special conditions are defined for connections in neutral and ground circuits. In the breaking capacity tests, the current given to flow for 200 ms should be interrupted by the functional unit within this period, and there should be no mechanical deterioration, insulation problems or deterioration in the protection degree during this process.
10.12) Electromagnetic compatibility
In general, applications are carried out, both via cable and air, in experiments where the interaction of devices is verified. Here, the experiments are grouped under two main groups as immunity and emission. Detailed information about the test contents can be obtained from other articles.
Clause 11 of the standard defines the tests that manufacturers must carry out in their factories;
Verification should consist of the following categories:
1. Construction (Clause 11.2 - 11.8)
- Degree of protection of assemblies
- Clearances and creepage distances
- Protection against electric shock and integrity of protective circuits
- Incorporation of switching devices and components
- Internal electrical circuits and connections
- Terminals for external conductors
2. Performance (Clause 11.9 - 11.10)
- Dielectric properties
- Connections&Functions
Annex D part of the standard is a guide defining the path to be followed for design verification. This table clearly defines which item application can be verified by which methods. For the 12-item 'type test' processes;
- Test requirement
- Calculation applicability
- The usability of the design rules has been analyzed one by one and presented to the manufacturer's information.