SI23380A - Procedure for testing safety of electric devices with installed active arresters - Google Patents

Abstract

A procedure for testing the safety of electric devices with installed active arresters or active RCDs is characterised in that a holistic test of electric equipment with installed active arrester or active RCD can be carried out according to this procedure. It is characteristic for the procedure that it connects suitable sources of signals and measuring circuits with measuring couplings (test socket and IEC connection) to enable a quick, safe and unharmful execution f the holistic test without switching over and to keep the active arrester or active RCD switched on until necessary.

Description

Testing procedure for the safety of electrical devices with built-in circuit breakers

The invention belongs to the field of testing and testing of electrical equipment, more specifically to the field of testing the safety and correct operation of this equipment.

A technical problem

A technical problem solved by the invention is the process of testing the safety and correctness of the operation of electrical equipment with a built-in active circuit breaker. Among other things, electrical distributors and extension cords are an example of such equipment. The feature of active circuit breakers is that they need a connected voltage to hold the circuit at all, but these circuit breakers may have a built-in leakage detection function and serve as active leakage circuit breakers. This characteristic of requiring a supply voltage limits the conduct of electrical safety testing in a quick and easy manner.

The invention describes a solution for how fast, harmless and risk-free testing of the electrical safety of electrical equipment, in particular electrical extension cords and manifolds with integrated circuit breakers, can be performed without unnecessary movement of the test piece.

The prior art

Portable Appliance Testers have a known solution where, in the context of electrical testing, the possibility of testing a leakage current switch (RCD) and continuity of a protective conductor (Megger PAT300) without switching or switching the test piece. That's not enough. It is also necessary to check the insulation resistance or leakage of the supply lines to the protective conductor, and the correctness of the connections. However, in the prior art, it is not possible to perform these tests without changing the measurement links (flow) during the test.

Description of solution to a technical problem

Any electrical equipment that is connected to the mains can be a source of danger to the user. Examples of such electrical equipment include, but are not limited to, connecting cables, extension cords, distributors and the like. Electrical equipment often contains additional switches or circuit breakers to ensure safety. Circuit breakers or switches in the equipment interrupt the power supply circuit to prevent damage or danger of electric shock in the event of a fault. These circuit breakers have several options, for example, that they need to be provided with additional power to maintain a closed circuit, so circuit breakers are active. In case they contain a circuit for detecting leakage currents, these are active leakage current protection switches. Leakage-current circuit breakers are further subdivided according to their intended use, their common common designation being RCD, therefore, the active RCD and active circuit breaker codes used herein will be the general designation for the purpose of the present invention.

The safety of electrical equipment must be tested to ensure its safe use. Electrical testing is well described in international and national standards (for example, DIN VDE 0701-0702).

Typical causes of danger are, for example, a broken protective conductor, improperly connected conductors, poor insulation, high leakage currents, malfunctioning. Typical measurements to evaluate the safe use of electrical equipment or measurements to test electrical safety are:

- resistance of connection to the protective conductor;

- insulation resistance, where possible and reasonable;

- leakage or alternate leakage current;

- correct connection of the power connections;

- RCD break time.

The use of active RCDs or active circuit breakers is one of the more common methods of protection. The main purpose of using RCDs of various types is to protect users of electrical equipment from the risk of electric shock from leakage currents.

Active RCDs or active circuit breakers require a supply voltage to enable the solenoid coupling to hold the closed circuit breaker. The active RCD or active circuit breaker is usually supplied with the required supply voltage by switching the clutch, electronically or electromagnetically, to the circuit breaker, by holding a button or mechanical actuator, to hold the circuit breaker engaged until the voltage is present. In this way, the uncontrolled switching on of electrical equipment or electrical equipment connected to such equipment is prevented. When such an active RCD or active circuit breaker is not switched on, the circuit breaker is unlocked and is a circuit that

located behind the active RCD or active circuit breaker, isolated from the supply voltage.

In this regard, the following measurement and technical problems occur in safety testing:

- with the active RCD or active circuit breaker unlocked, it is not possible to carry out other tests of the test subject's safety other than measuring the continuity of the protective conductor.

- Due to the active RCD or active circuit breaker being unlocked, it is not possible to carry out the usual safety and functional preliminary tests, which are typically performed by electrical safety testers of electrical equipment. Preliminary tests are typically performed with energy-limited sources in order to avoid unnecessary ejection of protective switches in the installation, tester or tester, or unnecessary occurrence of dangerous voltage on the contacting conductive parts of the test item, or unnecessary additional material damage in the event of failure of the test piece in the part located behind the active RCD or active circuit breaker.

- In the case of extension cords and connecting cables without active RCDs or active circuit breakers, the complete electrical safety test can typically be performed by connecting the meter between the measuring socket and the IEC measuring connector of the tester. The tester measuring circuit enables all necessary tests to be carried out without overtaking. However, for extensions and connecting cables with an active RCD or an active circuit breaker, all the necessary tests cannot be performed because the testers do not contain appropriate electronic circuits.

The invention describes a measuring procedure and measuring sub-assemblies that easily solve the technical problems. The procedure and the electronic subassemblies are described in detail below in the case of an electrical safety test of an extension cable with a built-in active RCD.

Pictures show:

Figure 1 presents typical examples of electrical equipment (extension cord or distributor) with built-in RCD.

Figure 2 represents part of the electrical tester structure.

Figure 3 represents an already established principle for measuring the continuity of a protective conductor connection.

Figure 4 presents the principle of measuring the correctness of connections of electrical equipment with the built-in active RCD.

Figure 5 represents the principle of the test in the electrical equipment of the built-in active RCD.

Figure 6 presents the principle of measuring leakage currents of electrical equipment with built-in active RCD.

Figure 7 presents the ease of comprehensive testing of electrical equipment with built-in active RCD.

Figure 1 shows schematically the test pieces (6 and 8) with several sockets (7). The tester is via a power connector, e.g. plug connector with phase conductors (a), neutral (b) and protective (c) plugs into a power outlet

(10) tester (13). The test subject (6) with ordinary RCD (1) is only credited for presenting the difference against the test subject (8) containing the active RCD (5).

Ordinary RCD (1) and active RCD (5) contain a leakage current measuring unit (3) and an actuating unit (4) which causes the circuit breaker (2) to open when the leakage current exceeds a certain threshold. In both cases, the circuit breaker (2) must be switched on manually, since in the active RCD (5) and similarly in the active circuit breaker, in this case, the circuit breaker needs a power supply in order to retain a closed electrical circuit.

Figure 2 presents a simplified model of an electrical equipment tester (13) having a measuring / test socket (10) for connecting the test lead to the test lead, and one or more individual measuring connectors, e.g. probe connector (11). The whole tester is controlled by a microcontroller (20), which selects and manages the internal circuits according to the purpose of each type of test, and prepares the measuring part accordingly (16). The connector (12) is usually of the IEC type and is intended for comprehensive tests of extension cords, distributors and similar electrical equipment. For powering the test specimens, and thus the built-in active RCD or active circuit breaker, a source (17) may be provided which may be current limited (18) and have a controlled connection (19) to the measuring / test socket (10).

Figure 3 represents the principle of known measurement of the resistance of a connection of a protective conductor (c) of a test subject (8) by means of a tester of electrical equipment (13). In this case, the measuring part (16) is formed as a measuring part for measuring the low resistances (25). The measuring circuit consists of: resistance measuring part (25), connections to the measuring connector (11) or IEC measuring connector (12), connections to the measuring / test socket (10), connection of accessible parts on the measuring device (8) to the protective conductor, as are e.g. the protective connector of the socket (7) on the test piece (8), and the connection of the protective conductor (c) in the power supply cable. The low resistance measuring unit usually operates according to the I / O principle, measuring the voltage and current from its own source in the said circuit, where only the nominal or lowest measuring current and the highest measuring voltage are usually given for correct measurement.

Figure 4 presents the principle of testing the correctness of connections using an electrical equipment tester (13). The test determines whether the test lead (8) has properly connected power leads (a and b) and a protective conductor (c). For this test, the RCD (5) of the test item (8) must be included. In this case, the measuring part (16) is formed as a measuring part for testing the correctness of the connections (14). The measuring circuit consists of the measuring part (14), the connections via the measuring / test socket (10) and the IEC connector (12), the power leads (a, b) and the protective conductor (c) of the test piece (8), and the additional power (IEC) cable ( 15) for the detachable connection between test piece (8) and test piece (13). The measuring portion (14) contains a source whose voltage and current capacity must be large enough to activate and retain the active RCD (5) or the active circuit breaker, if fitted. The current capacity of the origin of the measuring module (14) may be limited so as not to prevent unnecessary shutdowns of protection switches in the installation, tester or tester, so as not to appear dangerous

the stress on the contacting conductive parts of the test subject, or unnecessary additional material damage in case of failure of the test subject in the part located behind the RCD (5). The measuring part (14) tests and measures different combinations of resistance and voltage between the individual terminals of the measuring / test socket (10) and the IEC connector (12) to give a result on the correct connection or the error detected.

Figure 5 presents an RCD switch test with an electrical equipment tester. For this test, the test subject's RCD (5) must be included. The measuring circuit consists of a measuring part for the RCD test (21), a voltage source (17), connections to the measuring socket (10) and the IEC connector (12), and a connected tester (8) via an additional power (IEC) cable (15). The voltage and current capacity of the source must be high enough to remain active RCD (5) and be able to run the appropriate test current. The test determines the suitability of the RCD operation, for example by measuring the switch-off time at the rated leakage current. During the test, the RCD must be switched on manually when it is switched off during the tests, whenever it is necessary if it is good. The current capacity of the source may be limited to prevent unnecessary disconnections of the protective switches in the installation, tester or test specimen, or unnecessary occurrence of dangerous voltages on the contacting conductive parts of the specimen, or unnecessary additional material damage in case of failure of the test specimen in the part located behind the RCD. (5). There is no need to limit current capacity if the connection test has already been performed in the previous steps.

Figure 6 presents the principle of leakage current measurement with an electrical equipment tester. For this test, the RCD (5) of the test item (8) must be included. The measuring circuit consists of a leakage current meter (22), a voltage source (17) on the measuring / test socket (10), a test piece (8) (impedance between the power supply and the protective conductor), and termination via an additional power (IEC) cable (15) to IEC connector (12). The voltage and current capacity of the source must be large enough to incorporate active RCD (5). The current capacity of the source (22) may be limited to avoid unnecessary ejection of protective switches in the installation, tester or test piece, or unnecessary stress on the contacting conductive parts of the test piece, or unnecessary additional material damage in case of failure of the test piece in the part located behind RCD (5). If the connection test has already been performed in the previous steps, no restriction is necessary. The leakage current meter may measure this current as a current in the protective conductor (c) or as a current difference with the differential current collector (26) occurring between the currents through the supply leads (a) and (b), or all the test leads of the test piece. To measure leakage current, it is sufficient to measure the currents on the measuring / test socket (10).

The test of connection accuracy is also important for measuring leakage currents, since it confirms that the entire test piece is energized. For example, if the phase conductor in the RCD test piece is interrupted, this cannot be detected by the leakage current test alone.

Figure 7 shows the actual ease of testing the electrical safety of electrical equipment, in the case of an electrical extension (8). For a complete test of the continuity of the protective conductor, the correctness of the connections, the leakage current and the active RCD or active circuit breaker, it is only necessary to connect the test piece (8) to the test socket (10) of the tester (13) and via an auxiliary power cable (15) to the IEC connector (12) . With the help of electronics in the tester (13), the whole test can be performed in one step without any movement. The only additional operation during the test is to activate the active RCD. The number of starts depends on the tests selected and the type of active RCD. If the test subject contains an active circuit breaker, the active circuit breaker must be switched on only at the beginning of the test and switched off after the tester has switched off the power to the test piece.

A typical procedure for testing electrical equipment and devices containing either an active RCD (5) or an active circuit breaker is as follows:

- Connect the test piece (8) to the tester via a measuring socket (10) and via a power (IEC) cable (15) to the IEC connector (12).

- Test the resistance of the connection to the protective conductor (Figure 3).

- A voltage is connected to the measuring socket (10). The active RCD (5) can be activated automatically, if this is done otherwise the meter manually activates the active RCD (5) or the active circuit breaker on the test piece (8).

- When the active RCD (5) or the active circuit breaker is switched on, the connection tests, leakage currents can be tested in any order and the RCD tests performed on the test subject.

- Depending on the type of RCD and the measurement parameters set, it is necessary to manually activate the RCD (once or several times) during the measurement.

- At the end of the test, the power supply on the measuring socket is switched off.

The tester (13) ensures the automatic connection of the relevant electronic modules to the measuring / test socket (10) and the IEC connector (12) and the corresponding visual or audible warnings. Standards generally require that a continuity test be performed first. The order of the remaining tests is irrelevant.

The advantages of the procedure for testing the safety of electrical equipment with a built-in active RCD or active circuit breaker according to the invention are as follows:

- a comprehensive test of the electrical safety of the test specimens is made, in accordance with the applicable standards, in such a way that no measurement connections are required during the test process,

- The tester provides protection in the case of short circuits with a current limitation. Protective elements installed in the test piece or in the installation are not activated.

For subjects who have an on / off switch made with an active circuit breaker or active RCD or used

in succession with the circuit breaker in the supply chain, all the tests connected to the power connector and conductive touching parts shall be carried out by this procedure, but do not require a test of the correctness of the connections if they do not contain a socket representing an extension of the supply chain.

Claims (3)

PATENT APPLICATIONS 1. A process for testing the safety of electrical devices (8) with built-in active circuit breakers or active RCDs (5), the process comprising the following steps: (i) connecting the test piece (8) to the test socket (10); (ii) powering the test piece (8) through the power connector (a, b); (iii) activation of the RCD (5) or circuit breaker; (iv) performing the intended tests and measurements; (v) disconnecting the power supply to the test subject; and (vi) disconnecting the test subject, characterized in that the active RCD (5) or active circuit breaker is engaged as required throughout the test procedure. Method according to claim 1, characterized in that no special switching of the measuring device (8) is required to perform the tests during the execution of the test or the test sequence. A method according to claim 1 or 2 for the purpose of ensuring safety, preventing the failure of other circuit breakers in the supply chain and preventing material damage due to high fault currents with the possibility of incorporating signal sources characterized by signal sources having a limited current capacity and they are at the same time sufficiently powerful for the active switches or active RCD in the test piece to function properly.