Könner & Söhnen generators are designed as IT systems and are equipped with basic protection through the insulation of the active, live parts according to DIN VDE 0100-410.
The PE pins in the sockets are connected to the generator’s body, as is the grounding screw. The generator housing is insulated from the live L and N conductors.
When the generator is used mobile, the protection separation with potential equalization is usually employed as a protective measure.
A layperson is only allowed to operate a single load on the protection separation without additional protective measures:
Protection precautions with more than one load may only be operated and monitored by electrical specialists or trained persons. It is important to ensure that the generator and the loads do not have a conductive connection to earth and are connected to each other via insulated potential equalization conductors. Cross connections with other circuits (e.g., TN network in the building) must be excluded. The length of the connections should not exceed 500 m:
An "electrically trained person" is someone who has been informed by an electrical specialist about their assigned tasks and the potential dangers of improper behavior, has been instructed, and has been informed about the necessary protective devices and safety measures.
In an IT system, where conductive earth contact of the body of the devices is not excluded, a proper insulation monitoring device must be installed:
In an IT system, where conductive earth contact (Re) of the generator or the body of the devices is not excluded, or some loads do not have a potential equalization contact, the generator must be grounded, and all devices must be individually protected by RCDs (FI switches):
In this system, in the event of a second fault, either the circuit breaker is triggered by a short circuit, or the RCD (first fault at the generator, second fault at the device), or one of the two RCDs of two devices (first fault at one and second fault at the other) will trigger if both are touched.
For loads that require a grounded neutral conductor (e.g., washing machines, heating), a TN system with grounding and a grounded neutral conductor must be used.
If the generator and the fault current protective device (RCD) are spatially separated, the connection cables must be laid in such a way as to prevent short-circuits and earth faults.
If a generator is converted into a TN system by placing a bridge between N and PE inside the generator, it must no longer be operated without grounding, and it must be prevented that a layperson unknowingly uses the generator as an IT system and connects loads without grounding the generator and without the necessary protective measures.
Generators with the IT-TN switch are therefore equipped with special sockets for house feeding with a 1h position (PE). Schuko and CEE sockets with a 6h position are deactivated when switching to the TN system, so that no load with Schuko plugs and CEE plugs with a 6h position can be supplied by the generator after the switch to the TN system. The socket with the 1h position is used for house feeding with a special cable. This cable also connects the generator to the house ground via the PE contact (at least 6 mm² copper per conductor).
However, most generators on the market are IT system generators and do not have IT-TN switches or sockets with a 1h position for house feeding in a TN system. We recommend not placing bridges between N and PE internally in such generators to prevent misuse of the modified generator by a layperson.
A TN network can be built with the generator. In certain cases, mobile use may require it (e.g., RV feeding). In that case, we recommend grounding the N conductor of the generator together with the generator's housing externally.
For this, you could use an adapter cable with N and PE branches, which can then be visibly connected to the generator's grounding screw along with the grounding.
Adapter cables with internal bridges should not be used (even if labeled) to prevent a layperson from using such a cable elsewhere or without grounding the generator, which could pose a danger.
A bridge between N and PE without grounding constitutes the first fault in an IT system, and such a system must not be operated!
In residential use, the house ground can be used. In mobile use in a TN system, proper grounding (cross ground, earth spike, etc.) must be performed. In the TN system, the generator itself and its neutral conductor (star point) must be grounded.
After such an adapter, an RCD can be used for touch protection. This is necessary if, for example, individual loads are to be connected after the adapter:
IMPORTANT: The neutral conductor of the generator is grounded at the house connection point via the main grounding busbar in the house when a bridge between N and PE is placed on the switch on the generator side, and no modification of the generator or adapter is necessary! The only exception is generators with internal ATS modules. More information on this can be found in our informational materials for each generator group on our website.
Here is an example of a house connection with an inverter generator through the feeding socket on the outside wall of the house:
The bridge between N and PE is placed on the switch in the house and connected to the house grounding. The generator remains as an IT system until it is connected to the house. This eliminates the possibility of misuse of the generator. The generator can be used mobile as an IT system, but when needed, it can be connected to the house with a cable and used as a power source in the TN network.
The switch switches emergency power-enabled consumers from the public TN or TT network to the TN network with the generator.
The generator itself (grounding screw) must be grounded either through the house ground or its own ground.
If the generator only has Schuko sockets, these can be used for house feeding, just like the CEE sockets. The Schuko plug can be turned around without affecting the house feeding because the two active contacts in the Schuko socket are equal. The two contacts are only defined as N and L in the house.
This does not affect the overload and short-circuit protection of the generator.
Current flow during a fault in a load or in the distribution:
Current flow during a possible fault in the generator:
Grounding the generator or a separate connection from its grounding screw to the house ground serves as protection in case of a PE conductor interruption in the power cable from the socket to the house ground or if the power cable has a cross-section smaller than what is required for grounding. This is absolutely necessary because the N conductor is connected to PE outside the generator. The cross-section of the grounding cable is standardized and should generally not be less than 6-10 mm² (copper) depending on the country.
The selection of a suitable generator should be made carefully, as an unsuitable generator can not only jeopardize the intended use but also destroy the equipment and put itself at risk. We sell emergency power generators and provide our recommendations for their use. Analysis of existing power supply systems and development of personalized emergency power solutions are separate services that are not part of the technical support for a generator.
Disclaimer:
This manual should only be regarded as a recommendation, it is illustrative, and must be adapted to the exact circumstances and conditions on-site during installation. The installation itself should be carried out in accordance with all standards and regulations. We take no responsibility for incorrect installations and their consequences.
