Home feed with diesel generators with and without ATS connection

The article is protected by copyright. Publishing the entire article or its parts without a clear reference to the source (a link to the Könner & Söhnen website) is not permitted.

Diesel generators with Schuko and CEE sockets with a 6h PE position are designed as an IT system and have basic protection through the isolation of the active conductors. The PE pins in the sockets are connected to the frame of the generator in the same way as the ground screw. Active L and N lines are isolated from the generator frame.

Build TN system with the generator

The emergency power supply in buildings must usually be provided as a TN system. In this case, the generator and its neutral conductor must be grounded. The ground screw on the generator must be connected to the main ground bar in the house with a 6-10 mm² copper cable. If this is missing, you have to build a grounding for the generator. The PE conductor from the socket on the generator goes to the ground screw in the distribution box, which in turn must be connected to the main ground bar. The N conductor from the generator socket must be grounded at the connection point in the distribution box. This can be done by placing a bridge between N and PE on the generator side of the switch.

The cable to the building is considered the generator output and the TN system is only created when the generator is connected to the building.

Operating the generator with bridged N and PE conductors without grounding is prohibited for personal safety reasons.

The generator itself remains an IT system and can therefore be used mobile without any problems. If you want to supply a house with it, you connect the generator to the earthing, lay the cable from the generator to the power inlet and the system is ready for operation.

Do my electricity consumers need 230V or 400V?

400V three-phase current is usually only required for devices where a rotating field is required. These are power consumers with 3-phase motors such as tools, pumps, etc.

Such electricity consumers as the electric stove, powerful instantaneous water heater, fan heater, electric boiler or sauna are connected to 3-phases only for the purpose of load distribution in the public grid and are in fact 230V electricity consumers that can be supplied by a 230V generator.

When operating from the public power grid, 230V power consumers with a total output of over 4.6 kVA must be connected to 3 phases for the purpose of load distribution; during emergency power operation, if an emergency power generator that is not suitable for unbalanced loads is used, they should be supplied with 230V, but may not be brought to full power so that the neutral conductor is not overloaded.

Such power consumers such as the electric stove are usually connected with a 5 x 2.5 mm² copper cable and so when operating from the generator, a pair of cooking zone, or the electric oven can be operated without any problems without the neutral conductor of the supply cable being overloaded. Provided the generator has enough power for this. The same applies to instantaneous water heaters, fan heaters, electric boilers, saunas etc. which have 230V heating elements internally and are in fact 230V power consumers.

Recommended connection plan in accordance with the VDN guidelines for planning, construction and operation of systems with emergency power generators for 230V power consumers:

Emergency power feed-in with a 1-phase house connection:

Emergency power feed-in via the power inlet on the outside wall::

This connection variant requires much less effort than a permanent installation of the generator, which only has advantages in the event of rare power outages.

A changeover switch is installed in the house distribution and a TN system is built on the generator side (bridge between N and PE). In the event of a body short (L against the power consumer housing), the current flows across the bridge from PE to N and the circuit braker on the generator is triggered. The generator ground screw must be connected either to house ground via the pre-installed grounding point or to a purpose-built earthing. The generator can be connected to the power inlet using a standard extension cable (suitable for the socket type). You don't need a permanent installation; the generator is only used in the event of a power outage and can be connected at any time without much effort.

Könner & Söhnen generators with a VTS system can be used to power both 230V and 400V power consumers, but not at the same time. The 400V mode is exclusively for 400V three-phase consumers that load all 3 phases symmetrically.

With emergency power supply without ATS, the generator will start manually. You then have to check the voltage supplied by the generator and only when the voltage and frequency (50-53Hz) are correct can you switch on the load. Before stopping the generator, you must first switch off the load and only then stop the generator so that no damage occurs to the electricity consumers and the generator itself due to transition processes. When switching from 230V to 400V mode and vice versa, you must first switch off the load, change the mode, check the voltage and only then switch on the load.

Models labeled ATSR can also be operated with an external ATS box.

The KS ATS 4/63 HD box is intended for diesel generators and has a 1-phase and 3-phase external power network connection with up to 63A per phase.

The KS ATS 1/40 HD box is intended for diesel generators and a 1-phase external power network connection with up to 40A per phase.

The power supply built into the ATS also supports the generator battery so that it always remains ready for operation and in the event of a power failure, the 12V power supply takes over.

The ATS control cable can also be extended. Recommended cross section 1.5 mm² per wire.

The ATS box monitors the voltage on the “City power” side of the A phase and automatically starts the generator in “Auto” mode as soon as there is no voltage. After the generator is started, its voltage is checked and the power supply of consumers entitled to emergency power is switched to the generator. Public grid is disconnected at all conductors. When the voltage returns to the “City power” side, the “Load output” is switched to the “City power” side and the generator will be stopped.

The 100-200W ohmic load (e.g. 2 x 100W light bulbs or IR light bulbs) is used to compensate for the non-linear small current consumers in a household such as routers, satellite switches, cell phone chargers, LED lighting, etc., which are only part of the consume sine wave and thus distort the voltage. It is important to avoid harmful harmonics for the electricity consumers at the moment when such electricity consumers are active alone in the house.

The ohmic load loads the parts of the sine curve of the voltage that are not loaded by non-linear electronic current consumers and thereby dampens the harmonics.

Voltage (yellow) and current (green) from a conventional generator under electronic load with and without ohmic load (100W light bulb):

You can see that the disturbing harmonics marked with the red arrows in the left picture are much smaller in the right picture and most electronic modules then work without any problems.

In conventional generators (also with AVR), the current is taken from the alternator winding and the shape of the voltage can differ from the sine wave depending on the design of the generator and the connected power consumers. The frequency of the voltage in a conventional synchronous generator is determined by the speed of the motor, which can fluctuate depending on the load. The value of 50-53 Hz is permissible and is within the tolerance range.

You must ask the manufacturer of the device in question whether you can use a conventional generator to power your sensitive devices, as this may solely be due to the design of the device in question.

The 400V socket can supply 400V three-phase consumers that load all 3 phases symmetrically. Complete 400V house feed is not permitted!

Here is the recommended connection diagram in accordance with the VDN guidelines for planning, construction and operation of systems with emergency power generators for 400V power consumers such as motors, pumps, etc., which load all 3 phases symmetrically:

This solution is intended exclusively for insensitive 400V power consumers that load all 3 phases simultaneously and evenly and is not suitable for a complete house feed with mixed 230V and 400V power consumers!

Please make sure that our generators are equipped with circuit breakers that trip immediately in the event of a short circuit, but not in the event of a slight overload. The response time of the thermal release depends on the level of overload and can take up to 1 hour, which is common for circuit breakers. Therefore, you must pay attention to the maximum permissible load (including reactive load) so that overload damage to the generator itself is avoided.

Our generators are emergency power generators and are not suitable for uninterrupted continuous operation.

We recommend running all of our diesel generators for up to 10 hours, then taking a 30-60 minute break to cool down.

Disclaimer:

These instructions can only be perceived as a recommendation, are descriptive and must be adapted to the exact circumstances and conditions on site during installation. The installation itself should be carried out in compliance with all standards and regulations. We assume no responsibility for incorrect installations and their consequences.