Why is it necessary to ground a diesel generator? Grounding of diesel power plants

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 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 main provisions of PES-7 for power networks with a dead-earthed neutral and the value line voltage 380 V, the resistance of the grounding device must 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.

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.
• Grounding copper wire corresponding 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 clamp.

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.

Bought a 1 phase generator. The neutral is separated from the earth. The house has a 3-phase input. On the input panel in the house, zero and earth are on the same block, that is, they are connected.
I plan to connect the generator through a reversible 4-pole switch, i.e. phases and zero in the gap. What about generator grounding? Is it possible to throw houses on the ground?

It is not possible, but by default, the generator frame must be connected to the house charger with a power cable. In general, worse, budget options allowed by the norms and common sense are possible and more. best options when the generator frame is not connected to the house charger. In any case, the generator frame must be grounded.

In addition to the fact that in 1-phase generators there is no zero by default, any power output should be groundedit is forbidden!

GOST R 50783-95 said:

ELECTRIC UNITS AND MOBILE POWER PLANTS WITH INTERNAL COMBUSTION ENGINES
10 SAFETY REQUIREMENTS

10.3 Schematic electrical connections mobile electrical units and AC power plants three-phase current must have an isolated neutral.It is not allowed to use any devices that create an electrical connection of phase and (or) zero wires or neutral with housing or neutral conductors or neutral with housing or earth directly or through an artificial zero point, except for devices for suppressing radio interference.

10.4 In mobile electrical units and power plants with a capacity of 1 kW and above rated voltage from 115 V and abovethere must be a device for permanent insulation monitoring, which allows you to measure (estimate) the insulation resistance relative to the body (ground) of the conductive parts of the electrical unit and power plant that are energized. For operation in conjunction with the local electrical network, mobile generating sets and power plants must have an automatic shutdown device. These devices should be monitored for proper operation.

It is not allowed to use permanent insulation monitoring devices operating on the principle of voltage asymmetry.

Unfortunately, only some manufacturers of autonomous power supply sources indicate this.

ENERGO generator instruction said:

This manual is valid for petrol generating sets of the company:
SAWAFUJI ELECTRIC COMPANY (Japan)

EA 6500 (SH 6500 EX)

HAZARD WARNINGS
Do not connect to the local power supply without a disconnector installed by a qualified electrician. …

BASIC ELECTRICAL SAFETY RULES
― to prevent the operation of the electric unit in case of a short circuit to the case ...

When operating the unit IT IS FORBIDDEN:
ground the neutral or connect it to the body;

Illiterate in electrical safety owners of autonomous power supply sources, who themselves do not comply with and advise others not to comply with these standards, argue their case by stating that portable and smoke-type generators and other autonomous sources of power supply of 220/380 volts when they are supplied with power at home, this does not apply, since they constantly standing in one place.

It’s necessary to think of such an assertion, like because the generator is called portable, then it is worn during operation or because the generator constantly stands in one place, the electricity generated by it becomes safe!

Also, sellers-installers who are illiterate in electrical safety, including some certified service centers connecting generators, or just hacks, tightly connect one of the generator outputs with neutral wire mains supply since without switching the neutral wire simpler circuit, installation, cheaper and easier to find components, as well as to fool the clumsy flame control circuit of some boilers, arguing that they say they are doing it right because they did it many times and how it works, which is comparable to an illiterate statement that it is enough to do wiring without VDT , grounding, since in millions of houses there is no VDT, 2 wires and millions have not been killed, so it is not necessary to install differential protection and use wiring with PE.

Even if an autonomous power source is foolishly connected to a power system with a TN grounding type, then it is impossible to somehow connect one of the power outputs of an autonomous power source to the neutral wire of the mains!

GOST R 50571-4-44-2011 (IEC 60364-4-44:2007) said:

SAFETY REQUIREMENTS. PROTECTION AGAINST VOLTAGE DEVIATIONS AND ELECTROMAGNETIC INTERFERENCE.

444.4.7 Switching power supplies
In TN systems, switching power from one source to another sourcemust be carried out using a switching device that simultaneously switches the line conductors and the neutral conductor, if present in the electrical installation (see figures 44. R9A, 44. R9B, 44. R9C).

Non-compliance with the above-mentioned electrical safety standards is every day an increasing danger for those who violate these standards, animals, as well as for installers repairing the supply network, since every day there are more autonomous power supply sources and their power for the population illiterate in electrical safety. !

This is not to mention that non-compliance with the above-mentioned standards increases the likelihood of a generator failure, up to the impossibility of repair, for example, due to a minor leak in the generator insulation, even if the generator is not working, since the machine does not protect against such a malfunction, but when such a dangerous connection will not work!

It should also be borne in mind if a circuit is being made that during a power failure in the network, only part of the wiring at home is powered from an autonomous source of electricity 220/380 volts, and the rest of the wiring remains connected to the mains, which is better not to do, then the installation of lines in the shield and in the wiring powered by an independent source of electricity and connected to the mains, which are located together, must be designed for 660 volts! This also applies to lines located nearby, fed from different autonomous power supplies 220/380 volts!

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.

Grounding is a connection electrical appliance with grounding device. Consider how it is carried out in relation to diesel power plants.

Generators, control panel and switchgear must be grounded before starting and operating. This process must be carried out for security purposes, in accordance with the requirements adopted in Russia.

What is a diesel generator ground?

The grounding system usually consists of:

• ground electrode. Most often, steel rods coated with copper are used for this, which are buried in the ground. Note that in this case it is impossible to use pipes of underground water or gas pipelines.
• 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 provided with access for inspection. In this place, according to the requirements, a sign must be placed that says that there is a grounding system here.
• Ground clamp. It is located near the main circuit breaker of the power plant.
• Ground conductor. It connects all non-live metal parts of the installation to the earth clamp.

It is important to know that the connection of the earth clamp to the municipal earth electrode often requires the formal approval of the local authorities. This is necessary in areas where, in addition to the power plant, there is an electrical network common use, and the owner is the only person who is connected to the public supply transformer. Otherwise, you will have to install a separate ground electrode.

The connection of the conductor with the electrodes is carried out by welding, and with generator set- with the help of a special bolted connection on the body of the unit. It is necessary to dig the elements of the grounding system into the ground to a depth of 2.5-3 m.

The number of rods that can provide good diesel generator grounding, is determined depending on the soil. Its loop connection should be small, but sufficient so that, in the event of a ground fault, the current flow will allow the protective devices to operate.

Any installation with a mobile generator must have ground electrodes that are connected to the conductor and neutral. Instrument cables and wires must be as short as possible and free from loops to avoid overheating.

Want to learn more about generators and their operating conditions? Contact the specialists of the online store "Buy for a summer residence". We will answer all your questions in detail and give qualified advice on the selection of a power equipment model that is right for you!