Checking circuit breakers up to 1000 V

After replacing or newly laid electrical wiring, it is necessary to install metering devices and all machines for normal operation of household appliances and ensuring the smooth operation of all types of connected equipment. The installed equipment needs to be checked for operation or, as it is commonly called, loaded. In this article, we will take a closer look at how to check circuit breakers with voltages up to 1000 V.

Briefly about circuit breakers

Circuit breakers are designed to act as switching devices required to conduct the load current in the normal operation of the equipment and the opening of the electrical circuit in emergency mode with increased or decreased stress.

AB are widely used due to ease of installation, reliability in operation, safety during replacement and maintenance, quick response at short-circuit currents or abnormal modes. Such machines are installed in electrical installations with both low and high power.

There are manual and remote control devices. In abnormal modes, the switch is automatically triggered. All devices are equipped with an overcurrent release. Some models are equipped, in addition to the overcurrent and undercurrent release. Such machines are designed to replace switches or fuses in plug fuses, which provides more reliable protection for household appliances and connected equipment.

AB are produced mainly for amperage from 6.3A to 6300A for AC installations up to 1 kV, with a different number of poles. These can be one-, two-, three- and four-pole circuit breakers.

More about circuit breaker device you can find out in our related article. Now I would like to additionally tell only about the fact that protection against abnormal modes is provided by an electromagnetic release, thanks to which the device is turned off.

There are two types of releases:

• electromagnetic or overcurrent release against short-circuit and overload currents (without time delay);
• thermal (electronic), triggered at currents significantly exceeding the rated values ​​of the load currents (with a time delay).

Both types of protection must comply with the regulatory documents of the manufacturer (PTEEP in Appendix 3). In order for the device to work normally, before installation of a circuit breaker it needs to be checked. This operation is called loading the machine, which we will discuss in more detail now.

Loading method

During loading, the main characteristics of the machines are measured (rated current, protection operation current, protection operation time in case of abnormal modes) on a special installation. All work on checking the functionality is carried out by special personnel who have access to such tests, with a certificate with a mark of admission to special work on testing electrical equipment.

The certificate must indicate the safety group and the voltage at which the employee can carry out checks (up to or above 1000v). The certificate must be signed by the chief power engineer of the enterprise that carries out the verification work. The method of loading AB in the factory must comply with GOST for low-voltage control and distribution equipment.

Equipment

In order to check (load) a circuit breaker, you need to assemble a fairly simple circuit that includes the equipment necessary for testing:

• connecting wires;
• KU - control key;
• LATR - laboratory autotransformer for changing the load;
  load transformer or load transformer (NT);
• ammeter as a shunt;
• TT - current transformer.

Device diagram for checking AB:

The loading technique requires partial dismantling of the device, after checking the serviceability - reassembly. The device for testing may be of a different type, the main thing is that an artificial current is supplied to the AV short circuit with the measurement of its value, and taking into account the response time of the protection of the machine in the electrical networks.

There are even special kits for checking AB, for example SINUS-1600, shown in the photo:

The process itself

The loading of the circuit breaker with an electromagnetic release is carried out to determine the time automatic operation within the protected area according to the factory specifications. For this, the load current is set on the test device, which is equal to the maximum amperage for this type of AB and the time, according to the factory specifications.

To check the thermal release on the test rig, three times the load current and the maximum tripping response time are set in accordance with the factory specifications. Usually this time is from 5 sec. up to 0.5 min.

All actions for checking the machine are discussed in detail in the video:

How to load AB with primary current

Home tests

All the results of the work carried out are recorded in the protocol. The document reflects the magnitude of the induced amperage and the operation time of the machine. The loading report is signed by the person conducting the tests. A sample of filling out the verification protocol is provided below:

Test timing

The frequency of tests should be specified in the accompanying regulatory documents of the manufacturer, but the recommended check is every three years during normal operation of the circuit breaker at rated current load. In the event of emergency operation or abnormal operation of the AV, the frequency can be changed, and an unscheduled check must be carried out. All recommendations apply to automatic devices and switches installed in production areas.

According to the PUE Ch.3.2, clause 1.8.37, the loading of automatic switches on the input and sectional protection devices, emergency lighting networks, fire alarm systems - 2% of AV group networks. PUE requirements for other electrical installations 1% of all installed machines.

In case of detection of circuit breakers that do not correspond to the factory specifications, a methodology for checking the entire batch is carried out. After loading, each device must be stamped with the logo of the laboratory conducting the test, the date of the test and the word "Tested" or "Best before... (date)". This indicates that the machine has been tested and is operational.

This is the method used to check automatic switches with voltages up to 1000 V. As you can see, you can even load the machine with a device assembled at home, the main thing is to know the safety precautions and test technology. We hope that now you know what and how to do in order to independently check the breaking capacity of the protection device.

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Good afternoon, please help to fill out the table. Automatic circuit breaker type IEK BA 47-29 C25 and the second AB Schn Elec In 400A Ir = 0.8xIn. The time range is included in the passport, i.e. I need 3,4,5,7 columns in the table. Thanks!

Tell me, is it necessary to load the machines if they were purchased and installed for the first time? And is there any NTD where it is spelled out?

In your protocol for loading the machines, the response time range is 7-23 seconds. Where did these numbers come from? Tell me please. And then the customer asks this question, but I cannot answer. PUE refers to the factory passport. I looked through several passports, there is nothing even close.