Load-break switches

A load-break switch is an electrical switch that is used to disconnect an electrical circuit from the power supply. It is often used in electrical installations and distribution systems to ensure a safe working environment for maintenance and repair work.

The load-break switch enables the electrical circuit to be disconnected without interrupting the power supply. In contrast to conventional switches, a switch-disconnector can also be operated under load (i.e. with current flowing) without an arc occurring.

The main purpose of a switch-disconnector is to safely disconnect the electrical connections so that work can be carried out on the system without risking the safety of people or equipment. In addition, the load-break switch enables clear identification of whether a circuit is switched on or off, making it easier to work on electrical systems.

Switch-disconnectors are used in various areas, such as industry, commerce and residential buildings. They can also be found in switch cabinets, control panels and distribution boards.

A load-break switch is an electrical switching device that is used to disconnect an electrical load from the power source. It is normally used in low-voltage systems and serves to safely interrupt the connection between an electrical load and the power supply.

The switch-disconnector consists of a switching mechanism, which usually consists of a switching contact and an actuating mechanism. The switching contact opens and closes the circuit, while the actuating mechanism controls the switching contact.

The switching contact consists of two parts: a fixed contact and a moving contact. When the switch-disconnector is switched on, the contacts are closed and the current can flow unhindered. When the switching mechanism is actuated, the switching contact opens and the connection to the power source is interrupted.

The actuating mechanism may vary depending on the type of switch-disconnector. With manual switch-disconnectors, the switching mechanism is triggered by manual operation of a switching handle or rocker switch. With automatic switch-disconnectors, the switching mechanism can be triggered either by an electrical impulse or by another automatic control system.

The purpose of a load-break switch is to ensure safe disconnection of the load from the power source. This may be necessary, for example, to carry out maintenance work on the electrical system or to disconnect the load from the mains in the event of a fault or power failure.

It is important to note that a switch-disconnector is not designed for switching under load. This means that it should not be used to open or close a circuit when current is flowing. Instead, the load-break switch should only be used to disconnect a load from the power source when no current is flowing.

There are various types of switch-disconnectors, which differ in their design and mode of operation. The most important species are:

1. Screw disconnector: This type of switch-disconnector consists of a movable contact that is connected to the fixed contact by a screw. The contact can be opened or closed by turning the screw.

2. Jack disconnect switch: With latch disconnectors, the moving contact is connected to the fixed contact by a latch. The contact is opened or closed by engaging or releasing the latch.

3. Knife disconnector: This type of switch-disconnector consists of a movable and a fixed contact, which are shaped like blades. The contact is opened or closed by inserting or removing the movable contact.

The differences between the various types of switch-disconnectors lie mainly in their design and mode of operation. Screw disconnectors are simple and robust, but they require manual operation. Latch disconnect switches offer better handling as they can be easily engaged and disengaged. Knife disconnectors, on the other hand, are particularly suitable for high currents and voltages as they offer a larger contact surface.

Switch-disconnectors are typically used in electrical distribution systems, switchgear, transformer stations, industrial plants and buildings. They are used to safely isolate circuits and enable electrical consumers or systems to be switched off in order to carry out maintenance work or interrupt the flow of electricity in an emergency. Switch-disconnectors are therefore important components in electrical safety technology.

Various safety regulations and standards apply to the use of switch-disconnectors to ensure safe use. The most important of these include:

1. DIN VDE 0108: This standard specifies general requirements for electrical equipment, including switch-disconnectors. It covers aspects such as protection against electric shock, the selection and installation of equipment as well as maintenance and testing.

2. DIN EN 60947-3: This standard specifies requirements for switch-disconnectors for rated voltages up to 1000 V AC and 1500 V DC. It concerns both the construction and function of the switches as well as their marking, testing and maintenance.

3. Ordinance on Industrial Safety and Health (BetrSichV): This regulation specifies requirements for the safe operation of work equipment, including electrical equipment such as switch-disconnectors. It contains specifications for regular inspection, maintenance and documentation.

4. Technical rules for operational safety (TRBS): These rules specify the requirements of the BetrSichV and provide practical instructions for the safe use of equipment. TRBS 1203 deals, for example, with the testing of electrical systems and equipment.

5. Trade association regulations (BGV): Depending on the industry and area of application, specific regulations of the trade association may apply, which define additional requirements for the use of switch-disconnectors. These regulations are intended to ensure the safety and health protection of employees.

It is important to observe the applicable regulations and standards and to ensure that the switch-disconnectors are installed, maintained and tested accordingly to minimize potential hazards.

The maintenance and servicing of switch-disconnectors is generally carried out in accordance with the manufacturer's instructions and the applicable standards and regulations. Here are some steps that are usually carried out when servicing and maintaining switch-disconnectors:

1. Visual inspection: A regular visual inspection of the switch-disconnectors can indicate obvious damage or signs of wear. Attention should be paid to damage to the housing, contacts, insulators and other parts.

2. Cleaning: The switch-disconnector should be cleaned regularly to remove dirt, dust or other impurities. This can be done with a dry or slightly damp cloth.

3. Checking the contacts: The contacts of the switch-disconnector should be checked for wear or damage. If necessary, they can be cleaned, readjusted or replaced.

4. Lubrication: If the switch-disconnector has lubrication points, these should be lubricated regularly with a suitable lubricant to ensure smooth movement of the switching mechanisms.

5. Function test: The load-break switch should be checked regularly to ensure that it is working properly. This can be done by operating the switch manually or by using test devices.

6. Documentation: All maintenance and servicing work carried out should be documented in order to obtain an overview of the condition of the switch-disconnector and to ensure traceability if required.

It is important to note that the exact maintenance and servicing measures may vary depending on the type, size and area of application of the switch-disconnector. The manufacturer's instructions and the applicable standards and regulations should therefore always be observed. If in doubt, a specialist should be consulted.

The following attributes and features should be taken into account when selecting a switch-disconnector:

1. Rated current: The switch-disconnector should support the required rated current for the application. The rated current indicates how much current the switch can safely disconnect under normal operating conditions.

2. Nominal voltage: The switch should support the required rated voltage for the application. The rated voltage indicates how much voltage the switch can safely disconnect.

3. Switching capacity: The switching capacity indicates how much current or voltage the switch can safely disconnect in the event of a fault. It is important that the switch has the required switching capacity for the application to ensure safe disconnection.

4. Switching position: The switch should have the required number of switching positions. This can vary depending on the application, e.g. on/off switching or multiple switching positions.

5. Protection type: The degree of protection indicates how well the switch is protected against the ingress of foreign bodies and moisture. Depending on the location and environment, the switch should have a suitable degree of protection.

6. Mechanical service life: The mechanical service life indicates how many switching cycles the switch can perform under normal operating conditions before it needs to be replaced. A longer mechanical service life generally means greater reliability and a longer service life for the switch.

7. Actuation type: The switch can be either manual (manually operated) or motorized (electrically operated). The choice of actuation type depends on the application and the operating requirements.

8. Additional functions: Depending on the requirements of the application, additional functions such as residual current protection, overvoltage protection or remote control may be required. These should be taken into account when selecting the switch.

9. Certifications and standards: The switch should comply with the relevant national and international standards and certifications to ensure safety and quality.

10. Costs: The cost of the switch should also be taken into account. It is important to find an appropriate price-performance ratio that meets the requirements of the application.

A faulty or poorly maintained switch-disconnector can have various negative effects on the power grid and the connected devices:

1. Power grid faults: If the load-break switch does not function properly, this can lead to power failures or voltage fluctuations. This can affect the entire power grid and lead to interruptions or instability in the power supply.

2. Damage to connected devices: A faulty load-break switch can lead to improper power supply, e.g. unexpected voltage peaks or power surges. Such electrical interference can damage sensitive electronic devices or impair their functionality.

3. Security risk: A faulty or poorly maintained switch-disconnector can pose a safety risk. If the switch does not switch off properly or does not react when required, this can lead to electrical accidents or a fire hazard.

4. Energy loss: A faulty switch-disconnector can lead to energy losses as it may not work efficiently and cause unnecessary power consumption. This can lead to higher electricity costs for the end consumer.

It is therefore important to regularly check, maintain and, if necessary, repair or replace the switch-disconnector to avoid these potential problems and ensure a safe and reliable power supply.