Grounding of diesel generators. Operating modes of neutrals in electrical installations Diesel generator grounding scheme

What power to take the generator? How to install it? Where to connect it? What can be connected to an electric generator?... In this article, we have collected the 10 most popular questions and tried to answer them in a simple, understandable language. We hope that the answers to them will help you in choosing an electric generator. Here are 10 basic questions about the generator and the answers to them.

1. How much powerful generator should I purchase?

The expected power of the generator depends on the amount of electrical loads that you want to use at the same time. Power is measured in Watts (W). First, add up all the loads that you are going to use at the same time. Then, as a precaution, find out which household electrical appliances your home may have high inrush currents (refrigerators, air conditioners, pumps) Add it all to the total.

The fact is that some appliances, such as air conditioners, refrigerators, pumps, tend to use a lot of energy when starting (starting up) - usually 2-3 times more than they use during operation.

You need to make sure that your generator can handle relatively large appliances starting normally, make sure they don't overload the system when starting all the appliances at the same time.

The generator has two units that determine its power: nominal and maximum. The generators are provided with overload protection, which can work at the time of the simultaneous start of electrical appliances. Therefore, you should purchase a generator with some power reserve.

2. What loads should be powered by the generator?

Based on our own many years of experience installing and maintaining generators, we recommend that you provide the main consumers, which include:

1) Heating and all devices related to providing heat (boiler, pumps, etc.).

2) A couple of lighting circuits.

4) Refrigerator.

5) Microwave.

6) Garage doors.

7) Downhole pump.

8) Alarm.

If the power of the backup generator is sufficient, then secondary loads can also be connected: drainage pump, ventilation...

Equipment manufacturers indicate the power of the devices on the devices themselves or in the product passport. Also on many sites you can find an online calculator that will help you choose the power of the generator.

4. Do I need to hire an electrician to connect the generator to electrical network Houses?

Most safe way connecting the generator to the electrical network at home is to use additional device- AVR - automatic switching on of the reserve. The ATS is connected to the mains after the meter, and the generator is connected directly to the automation. When you start the generator, it disconnects the house from the city power grid and powers only those electrical appliances that you have allocated. Thus, the generator will not be overloaded.

If you are an amateur electrician, you have some knowledge of electricity but no experience in installing equipment of this type, it is best to contact a specialist to install the equipment. After all, the reliability of the entire power system of your home largely depends on how competently and efficiently the installation and commissioning of equipment is carried out.

5. Can't I just plug the generator into an outlet?

No and no again! We have already seen many times what this can lead to. This is very dangerous for a number of reasons. For example, if someone forgets to disable the main circuit breaker, then the generator can send power supply to the external network with all the ensuing consequences, if at that time repair work is underway on the line ...

Key points to know for correct connection generators are discussed in this article:

6. What is the difference between standby generator and emergency generator?

The backup generator is installed permanently and is designed to supply most electrical appliances. The emergency generator is a small, portable unit that can be taken outside the premises and connected to the ATS. Or it can be connected to electrical loads via extension cords.

7. If it's raining or snowing outside, can I put the generator in the garage and run it there as long as the door is left open?

No. Never run a generator inside a home, inside a garage, under a shed, on a porch, inside a porch, or near open window. Even with the garage open, carbon monoxide (CO) from generator exhaust can cause poisoning or, in the worst case, death.

8. What other safety tips should I keep in mind?

If the generator is installed permanently, use smoke detectors and carbon monoxide detectors, at least when using the generator. The generator should be located at least three meters from the house to minimize the risks of poisoning carbon monoxide(CO). Never fill the generator with fuel while it is hot.

9. Generators are loud enough. What can be done about it?

Unfortunately there aren't many options. Use generators inverter type, where the speed depends on the load. You can also purchase generators in a soundproof casing. In addition, you can purchase a special soundproof all-weather container in which the generator is placed.

Some craftsmen are experimenting with additional mufflers from motorcycles and ATVs. This can be done if you have the necessary skills. But be aware that in most cases this will void the generator warranty.

The easiest way to reduce noise from a mini power plant is to reduce the electrical load.

10. Do I need to ground the generator?

Follow the instructions in the user manual. If the manual requires the generator to be grounded, do so. The easiest way is to connect a 4-6 mm wire to the ground terminal on the generator. Connect the wire to a copper or iron 1.5 m rod that can be driven into the soil next to the generator.

As an alternative to the ground rod, you can connect the ground wire from the generator to inside the house at the main switchboard.

Most people know that a grounding system is necessary for electrical safety when installing a generator. However, they have enough general idea that grounding is a special connection of the mains or electrical appliances with a grounding mechanism at a certain point. The question arises, how to properly ground a diesel generator?

With regard to electrical safety measures, commonly used diesel power plants and their associated devices (control panel, power switching system, automatic transfer device, distributors, etc.), which includes a diesel generator set, are classified as electrical equipment with a voltage of not more than 1 kV.

These power plants are used in power networks where the neutral of a transformer or generator is connected to a grounding mechanism:

• directly
• through the resistance of devices
• doesn't connect at all

Therefore, the first version of the neutral can be called dead-earthed, and the second - isolated. The neutral of the second type is usually used in the case of using a diesel generator as an additional power source that ensures its autonomous delivery, and when reserving the main electrical network, the neutral of which is of a solidly grounded type, the generator is connected to the grounding mechanism through resistance or not connected at all. Let's name such mechanisms:

It is important to remember that the organization of grounding diesel power plants is a necessary measure to ensure safe use this equipment. That is why, when installing a grounding system, one should strictly follow the specially developed rules (PES-7).

This statement is true for absolutely all models that can be seen in the section diesel generators >>>

To organize grounding, grounding devices are required:

• Grounding - is a single conductor (electrode) or a system of such electrodes that are in electrical contact with the ground.
• Ground conductor- a device that connects the grounding point and the ground electrode. To connect the ground conductor to the ground electrode, you will need welding machine, and for its connection to the electric generator - a bolted connection.

Cast natural grounding may speak reinforced concrete foundations buildings, pipes made of metal, etc. True, due to different reasons, when using them, the resulting resistance may not be low enough. In addition, it is forbidden to use pipelines for explosive and flammable compounds. In the event that a diesel generator is located in a building equipped with a ground loop, it is allowed to ground it through this loop. The best option for diesel station- this is the creation of an individual ground loop.

It is important to know! Taking into account the basic provisions of PES-7 for electrical networks with a dead-earthed neutral and a line voltage value of 380 V, the resistance of the grounding device should not exceed 4 ohms. It is considered optimal smallest value grounding circuit resistance indicator, which is explained by a larger value of the breakdown current to the ground and a faster response of the protective switch of the circuit.

Resistance is primarily determined by:

• the surface area of ​​the electrodes
• ground depth
• earth resistivity

In this case, the latter indicator is the main one, because it determines the resistance value to a greater extent. Soil resistivity also depends on a number of parameters: temperature, soil moisture, concentration of catholytes and electrically conductive mineral compounds. From this it follows that this indicator differs depending on the time of year and locality.

In order to qualitatively ground the electric generator and create safe conditions labor for workers, you should fulfill the entire list of requirements that apply to all components of the grounding mechanism, as well as carefully calculate its maximum allowable resistance. This calculation can be made only with a known indicator resistivity soil, which is measured by means of a special device directly in the work area. In this case, you should remember about seasonal coefficients. Normally, the resulting resistance value should not exceed the calculated standard.

There is no doubt that such work should be carried out only by qualified personnel using an electrolaboratory. Over the years, our company has acquired a huge amount of knowledge in the field of installation of ground loops for power generators. The technologies for carrying out all work are fully consistent with the PUE and PTEEP. After they are carried out, we are guaranteed to issue a passport for the installed equipment.

STEN company: installation of ground loops according to all the rules, full complex electrical measurements

Many people have heard about such a necessary measure of electrical safety as grounding, and in general they imagine that grounding is intentional. electrical connection any point of the network or electrical equipment with a grounding device. What is grounding in relation to diesel power plants?

With regard to electrical safety measures, widely used diesel generators and their associated equipment (control panel, load transfer panel, ATS, switchgears etc.), which are part of a diesel power plant, refer to electrical installations with voltage up to 1 kV, operating in networks with isolated and dead-earthed neutral. Accordingly, the diesel generator neutral can be either isolated or connected to a grounding device. The first option is more common when using a diesel power plant as an autonomous power source, and the second - when redundant centralized network with earthed neutral. In the second case, without fail, the neutral of the diesel generator must be deafly grounded, and the grounding system of the power plant must correspond to the grounding system of the existing electrical installation in this network. Let's list these systems.

IT is a system with an isolated power supply neutral and grounding of exposed conductive parts of electrical installations.

TT - system with solidly grounded neutral of the power source and grounding of electrical installations using an independent grounding device. For electrical installations in networks with a solidly grounded neutral, several TN grounding systems are used, in which exposed conductive parts are connected to a solidly grounded neutral of the power source with neutral protective conductors.

IN TN-C system in one neutral conductor, along its entire length, the protective and working neutral conductors are combined. In the TN-S system, the protective and working neutral conductors are separated along its entire length.

In the TN-C-S system, the zero protective and zero working conductors are first combined in one, and then divided into independent ones.

It is clear that in any case, when operating diesel power plants, a grounding device is indispensable.

The figure shows the application of the TN-S earthing system for a power plant used as backup source power supply and working in conjunction with four-pole ATS.

We must not forget that the grounding of a diesel power plant is a measure used for the safety of people, and therefore, carried out in strict accordance with the current rules (PUE-7). It is carried out using a grounding device, consisting of grounding conductors and grounding conductors.

A grounding conductor is a conductor (electrode) or a set of conductors that have electrical contact with the ground, and a grounding conductor is a conductor for connecting a grounding point to a ground electrode.

The grounding conductor is connected to the grounding conductor by welding, and its connection to the power plant by bolting. Reinforced concrete foundations of buildings, metal pipelines, etc. can be used as natural grounding conductors. However, by various reasons, in In this case, it is not always possible to achieve a sufficiently low resistance of the grounding device. In addition, the use of pipelines for explosive and combustible substances is unacceptable. If the diesel generator is located in a building with a ground loop, it is allowed to ground it through this loop. The best solution for a power plant is its own ground loop. According to PUE-7, in networks with a dead-earthed neutral with line voltage 380V, the resistance of the grounding device should be no more than 4 ohms. The lower the resistance of the ground circuit, the better, since in this case more current ground fault and protection relay operation speed. It depends mainly on the surface area of ​​the electrodes, the depth of their grounding, and the resistivity of the soil. Moreover, the latter is the main factor determining the grounding resistance. In turn, soil resistivity is determined by temperature, moisture content, electrolytes and electrically conductive minerals, and therefore varies depending on the place and season. The figure shows a standard ground loop arrangement, where 3,4,5 are options for vertical grounding conductors made of angle steel, pipe and round steel, respectively, 2 is a horizontal grounding conductor made of strip steel that connects all vertical earthing switches and to which a ground conductor 6 made of round steel is welded. To him with bolted connection 1 connected ground conductor from copper wire 8, which is connected at the other end to the main ground bus (GZSH) in the input-distribution device (ASU).

For effective grounding of the power plant and ensuring the safety of personnel, it is necessary to fulfill all the requirements for the elements of the grounding device, exact calculation its maximum allowable resistance. Such a calculation is possible only after measuring the soil resistivity using the device directly at the work site and must take into account seasonal factors. The measured resistance of the correct grounding device should not exceed the calculated norm. Later, during operation, different time year, the necessary checks and measurements must be carried out to control the condition of the power plant's grounding.

It is obvious that these works must be carried out by qualified specialists with the help of an electrical laboratory.

Our company has extensive experience in the installation of ground loops for power plants. The work is carried out in full compliance with the PUE and PTEEP, with the issuance of a passport for the ground loop. The STEN electrical laboratory performs the entire complex required measurements and checks, such as: checking the condition of the elements of the grounding device; checking the presence of a circuit and measuring the contact resistance between the grounding conductor, grounding conductors and grounded elements; earth resistivity measurement; measurement of resistance of any grounding device; device check protective shutdown; measurement of the loop current "phase - zero", etc. All results are recorded in the protocol.

To place an order for the performance of work, to find out their cost, you just need to contact the manager using the phone or e-mail.

Most people know that grounding is necessary for safety when installing any electrical appliance, including a power generator. At the same time, few people understand what it is and how exactly the grounding system ensures safety.

So, why is grounding necessary and what will happen if it is not?

To answer these questions, you first need to remember from school course physics, what is electricity- the movement of charged particles in a conductive substance (conductor). The human body is also a conductor of current.

Why is current dangerous? Everyone has heard the expression: "shocked." In this blow lies its danger to a person, starting with unpleasant sensations, ending with a fatal outcome. To receive an electric shock, it is not enough just to touch a wire or part of a live device - it is necessary that there is an electrical circuit.

In practice, there is always such a chain, since we are constantly standing on the ground or on the floor, holding or touching objects. On contact with a wet surface, the potential difference increases and electric shock can be fatal.

In order to protect yourself from electric shock, grounding is necessary. Grounding is a special connection of the electrical network or electrical appliances with a grounding mechanism at a certain point. The essence of grounding is that all metal parts of the equipment are connected to a wire that goes to the ground. It is through this wire that the electric current goes into the soil, and not through a person, thereby ensuring the safety of the latter.

Before starting and starting the operation of the electric generator, it must also be connected to a ground loop, made in accordance with the requirements of the PUE.

• Grounding electrode (ground electrode). Copper-plated steel rods are best suited for this, which are buried in the ground in a certain pattern. Note that in this case it is impossible to use pipes of underground water or gas pipelines.
• Ground clamp. It is located near the main circuit breaker of the power plant.
• Earthing copper wire of the appropriate section. It connects the electrode to the clamp. It is important to remember that the place where the ground electrode and wire are connected must be protected from accidental damage and must be accessible for inspection. In this place, according to the requirements, a sign must be placed that says that there is a grounding system here.
• Ground conductor. It connects all non-live metal parts of the installation to the earth terminal.

In order to effectively carry out all procedures for grounding the power plant and ensure safety, it is necessary to clearly follow all PUE requirements(Electrical Installation Rules) and accurately calculate the maximum allowable resistance. This calculation is only possible when measuring soil resistivity special device at the place of work. Moreover, seasonal factors must be taken into account.

Undoubtedly, the installation of the grounding device should only be carried out by qualified personnel using special tools.