WO2021001173A1

WO2021001173A1 - Protection system with a switchgear and a slide-in unit and method of inserting the slide-in unit into the switchgear

Info

Publication number: WO2021001173A1
Application number: PCT/EP2020/067116
Authority: WO
Inventors: Thomas Gattringer
Original assignee: Eaton Intelligent Power Limited
Priority date: 2019-07-03
Filing date: 2020-06-19
Publication date: 2021-01-07
Also published as: GB201909571D0; GB2585220A; CN114026756B; EP3994778A1; CN114026756A

Abstract

A protection system (1a..1h) with a switchgear (2a..2e) having a compartment (A) and a slide-in unit (3a..3e) in this compartment (A) is disclosed as well as a method of inserting the slide-in unit (3a..3e) into the compartment (A). The switchgear (2a..2e) comprises a switching device (4, 5) and a main power system (6) with first main connectors (7a, 7b). The slide-in unit (3a..3e) comprises a short circuit switch (8a..8c) connected to second main connectors (9a, 9b), an auxiliary power system (10) for powering a control unit (11a, 11b) controlling the short circuit switch (8a..8c) and for powering at least one sensor (13a..13d) connected to the control unit (11a, 11b). The electric connection to the auxiliary power system (10) is established at a first slide-in position (B), and the electrical contact between the first and second main connectors (7, 9) is established at a second slide-in position (C), which is reached after the first slide-in position (B) during insertion.

Description

Protection system with a switchgear and a slide-in unit and method of inserting the slide-in unit into the switchgear

TECHNICAL FIELD

The invention relates to a protection system, which comprises a switchgear with an compartment for receiving a slide-in unit and a slide-in unit, which is designed to be inserted in said compartment of the switchgear. Furthermore, the switchgear comprises at least one switching device, a main power system connected to the switching device and first main connectors, which are electrically connected to the main power system and which are arranged in the compartment for the slide-in unit.

In addition, the slide-in unit comprises a short circuit switch and second main connectors, which are electrically connected to the short circuit switch and which are electrically connected to each other in the ON-state of the short circuit switch and which are electrically disconnected from each other in the OFF-state of the short circuit switch. Finally, the slide-in unit comprises an auxiliary power system for powering a control unit, which is connected to control input of the short circuit switch, and for powering at least one sensor, which is connected to an input of the control unit. In addition, the invention relates to a method of inserting a slide-in unit of the above kind into an empty compartment of a switchgear of the above kind. Said method comprises the steps of moving the slide-in unit to a first slide-in position and from the first slide-in position to a different second slide-in position.

BACKGROUND ART

A protection system with a switchgear and a slide-in unit for the switchgear is generally known. In this context, WO 2017/167940 A1 discloses a mobile arc protection system, which comprises at least one arc sensor, an evaluating and control unit and an arc-extinguishing device. The arc sensor communicates with the control unit, which controls the arc extinguishing device. The arc extinguishing device has a specifiable number of electrical power connections for temporarily connecting the arc-extinguishing device to electrical conductors, in particular bus bars, of an electrical installation, in particular an electrical distribution installation.

A major drawback of known mobile arc protection systems is that a user needs a lot of expert knowledge how to connect the mobile part of the arc protection system to the switchgear. Often, the electric connections and/or data connections between the mobile part of the arc protection system to the switchgear have to be made in a predetermined sequence and/or in a predetermined timing so as to ensure that the arc protection system works correctly. Otherwise, the arc protection system may be in an ambiguous unsafe state after the mobile part of the arc protection system has been connected to the switchgear. Such an ambiguous unsafe state may result although all necessary connections have been made (but in a wrong sequence and/or in a wrong timing). Hence, a user of the arc protection system may feel safe although he is not protected by the arc protection system. Such a wrong

interpretation of the safety status may lead to major injuries and damage of the switchgear. It should be noted that teaching the users how to use the mobile arc protection system may be not sufficient, as missing carefulness and attention of maintenance personnel, maybe caused by time pressure to repair a broken switchgear, may lead to the same consequences.

DISCLOSURE OF INVENTION

Accordingly, a problem of the invention is to provide an improved protection system and an improved method to connect the mobile part of a protection system. In particular, a predetermined sequence and/or in a predetermined timing shall be ensured when connecting the mobile part of a protection system.

The problem of the invention is solved by a protection system as defined in the opening paragraph, wherein the electric connection to the auxiliary power system of the slide-in unit is made or established at a first slide-in position of the slide-in unit, and the electrical contact between the first main connectors and the second main connectors is made or established at a different second slide-in position of the slide- in unit, wherein the first slide-in position is reached before the second slide-in position when the slide-in unit is inserted into the compartment in the switchgear.

Furthermore, the problem of the invention is solved by a method as defined in the opening paragraph, wherein the electric connection to the auxiliary power system of the slide-in unit is made or established at the first slide-in position of the slide-in unit, and the electrical contact between the first main connectors and the second main connectors is made or established at the second slide-in position of the slide-in unit, wherein the first slide-in position is reached before the second slide-in position when the slide-in unit is inserted into the compartment in the switchgear.

In other words, a state change of the electric connection to the auxiliary power system takes place at a first slide-in position of the slide-in unit and a state change of the electrical contact between the first main connectors and the second main connectors takes place at a different second slide-in position of the slide-in unit. The compartment comprises an opening, which is used to insert the slide-in unit into the compartment, and the first slide-in position is closer to said opening than the second slide-in position to provide the above sequence. Accordingly, the electric connection to the auxiliary power system takes place at the first slide-in position of the slide-in unit before the electrical contact between the first main connectors and the second main connectors takes place at the different second slide-in position of the slide-in unit when the slide-in unit is inserted into the compartment of the switchgear. In contrast, the electrical contact between the first main connectors and the second main connectors is released at the second slide-in position of the slide-in unit before the auxiliary power system is disconnected at the first slide-in position of the slide-in unit when the slide-in unit is removed from the compartment.

By use of the above measures, a predetermined sequence and/or a predetermined timing is ensured when the mobile part of a protection system (i.e. the slide-in unit) is connected to the switchgear. In detail, the auxiliary power system powering the control of the short circuit switch is connected first. Then the short circuit switch is connected to the main power system of the switchgear. In that, an unambiguous and safe state of the control unit can be ensured at the time at which the short circuit switch is connected to the main power system. Hence, a user of the protection system cannot feel safe although he is not protected by the protection system. Major injuries and damage of the switchgear are thus avoided. Correct set up of the protection system is even ensured in case of missing carefulness and attention of maintenance personnel what can be caused by time pressure to repair a broken switchgear.

A short circuit switch generally is used to short the conductors of the main power system so as to quench an arc in the main power system. Generally, the risk for a short circuit is much higher during maintenance than during normal operation. Inappropriate use of tools may lead to an unintentional flashover. Beneficially, the switchgear does not need to have a short circuit switch because a short circuit is comprised of the slide-in unit for the time span of raised risk.

Further advantageous embodiments are disclosed in the claims and in the

description as well as in the figures.

Beneficially, the at least one sensor is built into the switchgear. For example, the switchgear may comprise current sensors or light sensors or a combination thereof. These sensors may be used to detect an arc flash and/or an overcurrent situation. In particular, an event can be classified as an arc flash if both excessive light and overcurrent is detected.

However, the at least one sensor may also be a portable sensor outside of the switchgear. External sensors, for example, may comprise light sensors and/or fault current sensors. An external light sensor may be used to detect an arc flash, in particular in combination with an internal current sensor. Alternatively or in addition, the protection system may comprise an external fault current sensor to detect unintentional current over the body of maintenance personnel.

In an advantageous embodiment of the protection system

the at least one switching device in the switchgear is embodied as a main circuit breaker, which connects an electric circuit downstream of the main circuit breaker to a grid connector of the switchgear for a power grid in its ON-state and disconnects said electric circuit from said grid connector in its OFF-state and

the short circuit switch of the slide-in unit is part of the electric circuit downstream of the main circuit breaker when the slide-in unit is positioned at the second slide-in position.

In this way, triggering the short circuit switch causes disconnection of the main power system from the grid because the short circuit current over the main circuit breaker in turn triggers the main circuit breaker.

Advantageously,

a connection between a first ground connector of the switchgear and a second ground connector of the slide-in unit is made or established at a third slide-in position and/or a connection between the control unit and the at least one sensor is made or established at a fourth slide-in position and/or

a connection of a communication system of the switchgear and a

communication system of the slide-in unit is made or established at a fifth slide-in position, wherein

one or more of the third slide-in position, the fourth slide-in position and the fifth slide-in position differ from another and/or differ from the first slide-in position and/or the second slide-in position.

In other words, the predetermined sequence and/or the predetermined timing when the slide-in unit of the protection system is connected to the switchgear does not only involve the sequence and/or timing of connecting the auxiliary power system and the main power system, but may involve other connections as well. For example, a connection between a first ground connector of the switchgear and a second ground connector of the slide-in unit (i.e. the connection of the slide-in unit to ground potential) is made or established at a third slide-in position, wherein the third slide-in position in particular is reached before the first slide-in position when the slide-in unit is inserted into the compartment in the switchgear. In other words, beneficially, the connection to ground potential takes place before the auxiliary power system is connected when the slide-in unit is inserted into the compartment in the switchgear. Alternatively or in addition, a connection between the control unit and the at least one sensor is made or established at a fourth slide-in position. Beneficially, the connection between the control unit and the at least one sensor is made or established before or after the electric connection to the auxiliary power system of the slide-in unit is made or established. In other words, beneficially the fourth slide-in position is located before or after the first slide-in position. In a very advantageous embodiment, the fourth slide-in position is located between the third and the first slide-in position (i.e. between connecting ground potential and the auxiliary power system) or between the first and second slide-in position (i.e. between connecting the auxiliary power system and the main power system). Alternatively or in addition, a connection of a communication system of the switchgear and a communication system of the slide-in unit is made or established at a fifth slide-in position.

Beneficially, the connection between the communication system of the switchgear and a communication system of the slide-in unit is made or established before or after the electric connection to the auxiliary power system of the slide-in unit is made or established. In other words, beneficially the fifth slide-in position is located before or after the first slide-in position. In a very advantageous embodiment, the fifth slide- in position is located between the third and the first slide-in position (i.e. between connecting ground potential and the auxiliary power system) or between the first and second slide-in position (i.e. between connecting the auxiliary power system and the main power system).

Beneficially the auxiliary power system is a low voltage system at a voltage of < 48V. Usually, a voltage of the auxiliary power system is lower than the voltage of the main power system. The voltage of the auxiliary power system particularly may be 24 V or 48 V, whereas the voltage of the main power system particularly may

be 1 10 V, 230 V or 400 V.

The auxiliary power system of the slide-in unit can be connected to an auxiliary power system of the switchgear at the first slide-in position, wherein the auxiliary power system of the switchgear in particular has the same voltage as the auxiliary power system of the slide-in unit. Alternatively, the auxiliary power system of the slide-in unit is connected to the main power system of the switchgear at the first slide-in position. In this case, the slide-in unit may comprise a step-down-converter to generate the auxiliary voltage from the main voltage.

It is advantageous,

if during insertion of the slide-in unit into the compartment of the switchgear at or after the first slide-in position, but before second slide-in position

a) a boot sequence of the control unit is performed and finished and/or b) a connection is set up between the control unit and the at least one sensor and/or

c) a connection is set up between a communication system of the switchgear and a communication system of the slide-in unit and/or

d) a check of a serviceability of the short circuit switch is performed and/or

if during removal of the slide-in unit from the compartment of the switchgear at or after the second slide-in position, but before first slide-in position

e) a shut down sequence of the control unit is performed and finished and/or f) a connection between the control unit and the at least one sensor is closed and/or g) a connection between a communication system of the switchgear and a communication system of the slide-in unit is closed and/or

h) a check of a serviceability of the short circuit switch is performed.

The protection system may need a number of steps until it is in a clear functional state and until a user can trust in the protecting function of the protection system when the slide-in unit is inserted into the compartment of the switchgear. In the same way, a number of steps may be needed to leave the switchgear in a clear functional state when the slide-in unit is removed from the compartment of the switchgear again. For example, there may be the need to boot and shutdown the control unit in steps a) and e), particularly if it is software based. In addition, there may be the need to set up and close a connection between a sensor and the control unit according to steps b) and f) and/or the need to set up and close a connection between a communication system of the switchgear and a communication system of the slide-in unit according to steps c) and g). It should be noted at this point that said

connections may be wired or wireless connections. Advantageously, also the serviceability of the short circuit switch can be checked when the slide-in unit is inserted and/or removed in steps d) and h). If step d) is positively finished, a user of the protection system can trust in the function of the short circuit switch. If step h) is negatively finished, the user of the protection system can be notified that the short circuit switch is not ready for the next use. For example, the short circuit switch should be repaired or replaced then, or consumables in the short circuit switch should be replaced.

In a very advantageous embodiment, an output device signals that

in case of insertion of the slide-in unit into the compartment of the switchgear a movement of the slide-in unit to and over the second slide-in position shall be delayed until one or more steps a) to d) have been finished positively and signals that said movement is allowed after said steps a) to d) have been finished positively and/or

in case of removal of the slide-in unit from the compartment of the switchgear a movement of the slide-in unit to and over the first slide-in position shall be delayed until one or more steps e) to h) have been finished positively and signals that said movement is allowed after said steps e) to h) have been finished positively.

In this way, a user of the protection system gets feedback whether it is allowed to move the slide-in unit beyond the first slide-in position so as to provide a clear functional state of the protection system when the slide-in unit is inserted into the compartment of the switchgear. In the same way, a user of the protection system gets feedback whether it is allowed to move the slide-in unit beyond the first slide-in position so as to provide a clear functional state of the switchgear when the slide-in unit is removed from the compartment of the switchgear. An output element may be a lamp, a display or a speaker for example.

In a further very advantageous embodiment, a movement limitation element, which is embodied as a blocking element,

in case of insertion of the slide-in unit into the compartment of the switchgear stops the movement of the slide-in unit between the first slide-in position and the second slide-in position until one or more steps a) to d) have been finished positively and releases the slide-in unit after said steps a) to d) have been finished positively and/or

in case of removal of the slide-in unit from the compartment of the switchgear stops the movement of the slide-in unit between the second slide-in position and the first slide-in position until one or more steps e) to h) have been finished positively and releases the slide-in unit after said steps e) to h) have been finished positively.

In this way, a movement of the slide-in unit to the second slide-in position is inhibited until a clear functional state of the protection system is guaranteed when the slide-in unit is inserted into the compartment of the switchgear. In the same way, a movement of the slide-in unit beyond the first slide-in position is inhibited until a clear functional state of the switchgear is guaranteed when the slide-in unit is removed from the compartment of the switchgear. The blocking element may comprise a bolt, which is moved electromagnetically against a stopper in the switchgear or away from the stopper. In particular, a blocking element may be combined with an output element to indicate the slide-in status. The blocking element may also comprise a spring biased bolt, which has to be moved away from a stopper manually, when the output element indicates to do so.

In yet another very advantageous embodiment, a cover

in case of insertion of the slide-in unit into the compartment of the switchgear covers a front connector and/or an operating element of the slide-in unit until one or more steps a) to d) have been finished positively and releases said cover after said steps a) to d) have been finished positively and/or

in case of removal of the slide-in unit from the compartment of the switchgear covers said front connector / said operating element after said steps e) to h) have been finished positively.

In this way, use of the slide-in unit is inhibited until a clear functional state of the protection system is guaranteed when the slide-in unit is inserted into the

compartment of the switchgear. In the same way, use of the slide-in unit is inhibited when a clear functional state of the protection system cannot be guaranteed any longer when the slide-in unit is removed from the compartment of the switchgear. An operating element for example may be a push button or a switch. A front connector for example may be used to connect a sensor or a mobile control unit to the slide-in unit.

In another very advantageous embodiment, a front connector and/or an operating element of the slide-in unit

in case of insertion of the slide-in unit into the compartment of the switchgear are disabled until one or more steps a) to d) have been finished positively and are enabled after said steps a) to d) have been finished positively and/or

in case of removal of the slide-in unit from the compartment of the switchgear are disabled after said steps e) to h) have been finished positively.

This is an alternative way, to inhibit use of the slide-in unit until a clear functional state of the protection system is guaranteed when the slide-in unit is inserted into the compartment of the switchgear. In the same way, use of the slide-in unit is inhibited when a clear functional state of the protection system cannot be guaranteed any longer when the slide-in unit is removed from the compartment of the switchgear. Again, an operating element for example may be a push button or a switch, and a front connector for example may be used to connect a sensor or a mobile control unit to the slide-in unit.

In the above embodiments reference is made to the first slide-in position and to the second slide-in position. However, the third slide-in position, the fourth slide-in position or the fifth slide-in position may take over the role of the first slide-in position or the second slide-in position in the above definitions. Furthermore, it is very advantageous if

one or more steps a) to d) have been finished before the slide-in unit reaches the second slide-in position when it is moved at a speed of 10 cm/s and/or

one or more steps e) to h) have been finished before the slide-in unit reaches the first slide-in position when it is moved at a speed of 10 cm/s.

By these measures, one or more steps a) to h) are finished between the first slide-in position and the second slide-in position in time when the slide-in unit is moved at usual speeds.

Finally, it is very advantageous if a movement limitation element, which is embodied as a damping element, creates a back force of more than 50 N if the slide-in unit is moved at a speed above 10 cm/s. By these measures, a speed is of the slide-unit is ensured at usual operating forces, which makes sure that one or more steps a) to h) are finished in time between the first slide-in position and the second slide-in position. On the other hand, a substantial back force in generated, when said speed is exceeded.

It should be noted at this point that the variants disclosed in the context of the protection system and the advantages resulting thereof equally apply to the disclosed method and vice versa.

BRIEF DESCRIPTION OF DRAWINGS

The invention now is described in more detail hereinafter with reference to particular embodiments, which the invention however is not limited to.

Fig. 1 shows a wiring scheme of an exemplary protection system;

Fig. 2 shows a cut out of a switchgear and the slide-in unit outside of the

compartment in oblique view;

Fig. 3 shows a detailed view of Fig. 2 with the slide-in unit partially inserted into the compartment;

Fig. 4 shows a rear view of the slide-in unit; Fig. 5 shows an embodiment of a slide-in unit with a movement limitation element;

Fig. 6 shows an example of a switchgear with a door closing an empty

compartment in oblique view;

Fig. 7 shows the switchgear of Fig. 6 with a slide-in unit partially inserted in the compartment;

Fig. 8 shows the switchgear of Fig. 6 with a slide-in having a number of

operating elements, front connectors and output devices on the front panel;

Fig. 9 shows the protection system of Fig. 8 with a cover covering the operating elements, front connectors and output devices on the front panel;

Fig. 10 shows an example of a protection system with external light sensors and

Fig. 1 1 shows an example of a protection system with an external fault current sensor.

DETAILED DESCRIPTION

Generally, same parts or similar parts are denoted with the same/similar names and reference signs. The features disclosed in the description apply to parts with the same/similar names respectively reference signs. Indicating the orientation and relative position (up, down, sideward, etc) is related to the associated figure, and indication of the orientation and/or relative position has to be amended in different figures accordingly as the case may be.

Fig. 1 shows a wiring scheme of a protection system 1 a of the proposed kind. The protection system 1 a comprises a switchgear 2a with a compartment A for receiving a slide-in unit 3a and the slide-in unit 3a, which is inserted in said compartment A of the switchgear 2a in Fig. 1.

The switchgear 2a in this example comprises two switching devices 4, 5 each comprising three switching contacts, a main power system 6 connected to the switching devices 4, 5 and first (metallic) main connectors 7a, which are electrically connected to the main power system 6.

The slide-in unit 3a comprises a short circuit switch 8a, second (metallic) main connectors 9a, which are electrically connected to the short circuit switch 8a, and an auxiliary power system 10 for powering a control unit 1 1 a, which is connected to control input 12 of the short circuit switch 8a, and for powering sensors 13a and 13b, which are connected to an input 14 of the control unit 1 1 a.

The electric connection to the auxiliary power system 10 of the slide-in unit 3a is made or established at a first slide-in position B of the slide-in unit 3a, and the electrical contact between the first main connectors 7a and the second main connectors 9a is made or established at a different second slide-in position C of the slide-in unit 3a wherein the first slide-in position B is reached before the second slide- in position C when the slide-in unit 3a is inserted into the compartment A in the switchgear 2a. The different slide-in positions B and C are symbolically shown in Fig. 1.

In the example shown in Fig. 1 , the auxiliary power system 10 of the slide-in unit 3a is connected to an auxiliary power system of the switchgear 2a at the first slide-in position B. In detail, the switchgear 2a comprises a voltage converter 15, which generates an auxiliary voltage based on the voltage in the main power system 6. A first auxiliary connector 16a is electrically connected to the voltage converter 15 of the switchgear 2a. When the slide-in unit 3a is inserted in the compartment A, a second auxiliary connector 17a is connected to the first auxiliary connector 16a thus connecting the auxiliary power system 10 of the slide-in unit 3a to the voltage converter 15 of the switchgear 2a. Accordingly, the auxiliary power system 10 of the slide-in unit 3a has the same voltage as the auxiliary power system of the

switchgear 2a in this example. In particular, the auxiliary power system is a low voltage system at a voltage of < 48V. Usually, a voltage of the auxiliary power system is lower than the voltage of the main power system 6. Hence the voltage converter 15 is a step down converter then. The voltage of the auxiliary power system particularly may be 24 V or 48 V, whereas the voltage of the main power system 6 particularly may be 1 10 V, 230 V or 400 V. In this example, the auxiliary power system 10 of the slide-in unit 3a is connected to an auxiliary power system of the switchgear 2a at the first slide-in position B.

Alternatively, the auxiliary power system 10 of the slide-in unit 3a may be connected to the main power system 6 of the switchgear 2a at the first slide-in position B if the slide-in unit 3a comprises a voltage (step down) converter 15 to generate the auxiliary voltage from the main voltage. In other words, the voltage converter 15 is arranged in the slide-in unit 3a then.

The switching device 4 in the switchgear 2a is embodied as a main circuit breaker in this example, which connects an electric circuit downstream of the main circuit breaker 4 to first grid connectors 18 of the switchgear 2a. The first grid connectors 18 of the switchgear 2a are (permanently) connected to the second grid connectors 19 of the power grid 20. The short circuit switch 8a of the slide-in unit 3a is part of the electric circuit downstream of the main circuit breaker 4 when the slide-in unit 3a is inserted in the compartment A, in detail when it is positioned at the second slide-in position C. The power grid 20 is a three phase system with the phases L1..L3 in this example. However, other power systems apply to the proposed protection system 1 a as well.

In this example, the sensors 13a and 13b are built into the switchgear 2a. The sensor 13a is a light sensor and the sensor 13b is a current sensor for the three phases L1..L3. These sensors 13a, 13b may be used to detect an arc flash D and/or an overcurrent situation. In particular, an event can be classified as an arc flash D or arc fault if there is both excessive light and overcurrent. Although, the sensors 13a and 13b are built into the switchgear 2a in this example, they may also be arranged outside of the switchgear 2a (see Figs. 10 and 1 1 ).

When the second auxiliary connectors 17a are connected to the first auxiliary connectors 16a, not only the voltage converter 15 is electrically connected to the control 1 1 a, but also the connection 21 between the control 1 1 a and the

sensors 13a, 13b is closed. In addition, a connection 22 between communication systems of the switchgear 2a and slide-in unit 3a, which a control line from the control 1 1 a to the main circuit breaker 4 is part of in this example, is closed. Fig. 1 showed a wiring scheme of an exemplary protection system 1 a. Figures 2 to 4 now show a first example of the mechanical structure of the slide-in unit 3b and the compartment A of the switchgear 2b. In detail, Fig. 2 shows a cut out of a

switchgear 2 and the slide-in unit 3b outside of the compartment A in oblique view, Fig. 3 shows a detailed view of Fig. 2 with the slide-in unit 3b partially inserted into the compartment A, and Fig. 4 shows a rear view of the slide-in unit 3b.

The switchgear 2b of this example comprises a frame 23a and rails 24 in the region of the compartment A. The slide-in unit 3b comprises a frame 25 with sliders 26, which are prepared to slide along the rails 24 when the slide-in unit 3b is inserted in the compartment A. However, the slide-in unit 3b may also comprise rolls which roll along the rails 24. On the frame 25 of the slide-in unit 3b there is mounted the short circuit switch 8b and a control unit 1 1 b (see Fig. 2).

The switchgear 2b of this example furthermore comprises a pin shaped first ground connector 27 reaching from the backside of the compartment A to the opening of the compartment A and a pin shaped first auxiliary connector 16b reaching from the backside of the compartment A to the opening of the compartment A, wherein the first ground connector 27 is a bit longer than the first auxiliary connector 16b.

Moreover, the slide-in unit 3b comprises a second ground connector 28 and a second auxiliary connector 17b each shaped like a slider (see Fig. 3).

The switchgear 2b of this example furthermore comprises a first main connector 7b at the backside of the compartment A which is part of a connector bar 29 vertically running through the switchgear 2b, and the slide-in unit 3b comprises second main connectors 9b at the backside of the frame 25 of the slide-in unit 3b (see Figs. 2 and 3).

It should be noted that although sliders 17b and 28 are used in the example of Figs. 2 to 4 to make the contact to the auxiliary power system 10 and to ground, other connection systems may be used as well, for example plug/socket connections. Generally, the position of the plugs and the sockets is not limited to the versions shown in the Figs., and the positions of the plugs and the sockets may be

exchanged. Furthermore, the connection to the main power system 6 is not limited to the depicted embodiment, but may be designed in a different way. It should also be noted that Figs. 2 to 4 do not show all entities of the protection system 1 b, which are shown in Fig. 1 , and Fig. 1 does not show all entities of the protection system 1 a, which are shown in Figs. 2 to 4. However, one easily understands that a real protection system can comprise all entities shown in Figs. 1 and 2.

The function of the proposed protection system 1 a, 1 b now is as follows:

When the slide-in unit 3a, 3b is inserted into the compartment A of the

switchgear 2a, 2b, several slide-in positions are reached. First, the optional third (grounding) slide-in position E is reached, where the second ground connector 28 contacts the first ground connector 27. At the first slide-in position B, the second auxiliary connector 17a, 17b contacts the first auxiliary

connector 16a, 16b thus making or establishing the electric connection to the auxiliary power system 10 of the slide-in unit 3a, 3b. Finally, at the second slide-in position C, the second main connector 9a, 9b contacts the first main

connector 7a, 7b. In other words, the first slide-in position B is reached before the second slide-in position C and the optional grounding slide-in position E is reached before the first slide-in position B when the slide-in unit 3a, 3b is inserted into the compartment A of the switchgear 2a, 2b. In this way, the electric system of the protection system 1 a, 1 b is automatically contacted in a preferred sequence when the slide-in unit 3a, 3b is inserted into the compartment A of the switchgear 2a, 2b. No expert knowledge is needed how the electric system of the protection system 1 a, 1 b should or must be connected. The same applies to the removal of the slide-in unit 3a, 3b from the compartment A of the switchgear 2a, 2b. Again, the connections are automatically released in a predetermined sequence.

In an advantageous embodiment, during insertion of the slide-in unit 3a, 3b into the compartment A of the switchgear 2a, 2b at or after the first slide-in position B, but before second slide-in position C

a) a boot sequence of the control unit 1 1 a, 1 1 b is performed and finished and/or b) a connection 21 is set up between the control unit 1 1 a, 1 1 b and the sensors 13a, 13b and/or

c) a connection 22 is set up between a communication system of the switchgear 2a, 2b and a communication system of the slide-in unit 3a, 3b and/or d) a check of a serviceability of the short circuit switch 8a, 8b is performed

The protection system 1 a, 1 b may need a number of steps until it is in a clear functional state and until a user can trust in the protecting function of the protection system 1 a, 1 b when the slide-in unit 3a, 3b is inserted into the compartment A of the switchgear 2a, 2b. For example, there may be the need to boot the control unit 1 1 a, 1 1 b, particularly if it is software based. In addition, there may be the need to set up a connection 21 between a sensor 13a, 13b and the control unit 1 1 a, 1 1 b. Moreover, there may be the need to set up a connection 22 between a

communication system of the switchgear 2a, 2b and a communication system of the slide-in unit 3a, 3b. Such a connection 22 may involve information exchange beyond communication between the sensors 13a, 13b and the control unit 1 1 a, 1 1 b.

Generally, said connections 21 , 22 may be wired or wireless connections.

Advantageously, also the serviceability of the short circuit switch 8a, 8b can be checked when the slide-in unit 3a, 3b is inserted. If this step d) is positively finished, a user of the protection system 1 a, 1 b can trust in the function of the short circuit switch 8a, 8b.

In an advantageous embodiment, during removal of the slide-in unit 3a, 3b from the compartment A of the switchgear 2a, 2b at or after the second slide-in position C, but before first slide-in position B

e) a shut down sequence of the control unit 1 1 a, 1 1 b is performed and finished and/or

f) a connection 21 between the control unit 1 1 a, 1 1 b and the sensors 13a, 13b is closed and/or

g) a connection 22 between a communication system of the switchgear 2a, 2b and a communication system of the slide-in 3a, 3b unit is closed and/or

h) a check of a serviceability of the short circuit switch 8a, 8b is performed.

Like above, a number of steps may be needed to leave the switchgear 2a, 2b in a clear functional state when the slide-in unit 3a, 3b is removed from the

compartment A of the switchgear 2a, 2b again. For example, there may be the need to shutdown the control unit 1 1 a, 1 1 b, the need to close a connection 21 between the sensors 13a, 13b and the control unit 1 1 a, 1 1 b and/or the need to close a connection 22 between a communication system of the switchgear 2a, 2b and a communication system of the slide-in unit 3a, 3b Advantageously, also the serviceability of the short circuit switch 8a, 8b can be checked when the slide-in unit 3a, 3b is removed from the compartment A. If this step h) is negatively finished, the user of the protection system 1 a, 1 b can be notified that the short circuit switch 8a, 8b is not ready for the next use. For example, the short circuit

switch 8a, 8b should be repaired or replaced then, or consumables in the short circuit switch 8a, 8b should be replaced. Such consumables may comprises

semiconductors, which usually are able to withstand just a few short circuits. It should be noted that although the short circuit switch 8a is a semiconductor switch in the example of Fig. 1 , the short circuit switch 8a may also be an electromechanical switch. Consumables can be the contacts of such a switch.

It should also be noted at this point, that although the connection 21 between the control unit 1 1 a, 1 1 b and the sensors 13a and 13b, the connection 22 between communication systems of the switchgear 2a, 2b and slide-in unit 3a, 3b and the connection to the auxiliary power system 10 system is made at the same first slide-in position B in the example of Fig. 1 , this is no mandatory condition. In contrast, the connection 21 between the control 1 1 a, 1 1 b and the sensors 13a 13b can be made at a different fourth slide-in position, and/or the connection 22 between communication systems of the switchgear 2a, 2b and slide-in unit 3a, 3b can be made at a different fifth slide-in position.

Beneficially, the fourth slide-in position is located before or after the first slide-in position B. In a very advantageous embodiment, the fourth slide-in position is located between the third (grounding) slide-in position E and the first slide-in position B or between the first slide-in position B and second slide-in position C. In other words, it is advantageous if the connection 21 between the control unit 1 1 a, 1 1 b and the sensors 13a and 13b is made or established before or after the electric connection to the auxiliary power system 10 of the slide-in unit 3a, 3b is made or established and advantageously after the slide-in unit 3a, 3b has been connected to ground potential.

Alternatively or in addition, the fifth slide-in position beneficially is located before or after the first slide-in position B. In a very advantageous embodiment, the fifth slide-in position is located between the third (grounding) slide-in position E and the first slide- in position B or between the first slide-in position B and the second slide-in position C. In other words, it is advantageous if the connection 22 of a

communication system of the switchgear 2a, 2b and a communication system of the slide-in unit 3a, 3b is made or established before or after the electric connection to the auxiliary power system 10 of the slide-in unit 3a, 3b is made or established and advantageously after the slide-in unit 3a, 3b has been connected to ground potential.

When the slide-in unit 3a, 3b is inserted in the compartment A, the protection system 1 a, 1 b inter alia can monitor in the switchgear 2a, 2b whether an arc flash D occurs. In particular, an event is classified as an arc flash D or an arc fault if both excessive light is detected by the light sensor 13a and excessive current is detected by the current sensor 13b. In turn, the control 1 1 a, 1 1 b outputs a close command to the short circuit switch 8a, 8b. In the ON-state of the short circuit switch 8a, 8b, the second main connectors 9 are electrically connected to each other. That is why the arc D is quenched. In contrast, in the OFF-state of the short circuit switch 8a, 8b the second main connectors 9 are electrically disconnected from each other allowing normal operation of the switchgear 2a, 2b.

The short circuit switch 8a, 8b of the slide-in unit 3a, 3b is arranged downstream of the main circuit breaker 4. In this way, triggering the short circuit switch 8a, 8b causes disconnection of the main power system 6 from the power grid 20 because the short circuit current through the main circuit breaker 4 causes the same to open its contacts. Generally, the main circuit breaker 4 in the switchgear 2a, 2b connects the electric circuit downstream of the main circuit breaker 4 to first grid connectors 18 of the switchgear 2a, 2b its ON-state and disconnects said electric circuit from said first grid connectors 18 in its OFF-state.

Although the main circuit breaker 4 is indirectly triggered in the above example, it may also directly be triggered via the connection 22. So, the control unit 1 1 can actively trigger both the short circuit switch 8a, 8b and the main circuit breaker 4.

Beneficially, the distance between the first slide-in position B and second slide-in position C is of such a kind that it allows for a complete set-up and/or shutdown of the protection system 1 a, 1 b at usual moving speeds of the slide-in unit 3a, 3b. A usual moving speed of the slide-in unit 3a, 3b in particular is below 10 cm/s. So, generally it is of advantage if

one or more steps a) to d) have been finished before the slide-in unit 3a, 3b reaches the second slide-in position C when it is moved at a speed of 10 cm/s and/or one or more steps e) to h) have been finished before the slide-in unit 3a, 3b reaches the first slide-in position B when it is moved at a speed of 10 cm/s.

By these measures, one or more steps a) to h) are finished between the first slide-in position B and the second slide-in position C in time when the slide-in unit 3a, 3b is moved at usual speeds.

To guarantee a proper set-up and/or shutdown of the protection system 1 c, a blocking element 30, which is a kind of a movement limitation element, may be used like this is shown in Fig. 5. The blocking element 30 comprises a cylinder and a movable/lockable rod in this example. However, the blocking element 30 may be of different design as well and it may also be oriented differently. In particular, the moving direction of the rod may be perpendicular to the moving direction of the slide- in unit 3a, 3b. In this case, the rod is moved against a stopper of the

switchgear 2a, 2b to inhibit the movement of the slide-in unit 3a, 3b. Generally, the blocking element 30 may be actuated electromagnetically or pneumatically for example.

This blocking element 30 in case of insertion of the slide-in unit 3a, 3b into the compartment A of the switchgear 2a, 2b stops the movement of the slide-in unit 3a, 3b between the first slide-in position B and the second slide-in position C until one or more steps a) to d) have been finished positively and releases the slide- in unit 3a, 3b after said steps a) to d) have been finished positively. In this way, a movement of the slide-in unit 3a, 3b beyond the first slide-in position B is inhibited until a clear functional state of the protection system 1 c is guaranteed when the slide- in unit 3a, 3b is inserted into the compartment A of the switchgear 2a, 2b.

Additionally or alternatively in case of removal of the slide-in unit 3a, 3b from the compartment A of the switchgear 2a, 2b, the blocking element 30 stops the movement of the slide-in unit 3a, 3b between the second slide-in position C and the first slide-in position B until one or more steps e) to h) have been finished positively, and the blocking element 30 releases the slide-in unit 3a, 3b after said steps e) to h) have been finished positively. The moving direction of the rod is perpendicular to the moving direction of the slide-in unit 3a, 3b then, and the rod is moved against a stopper of the switchgear 2a, 2b to inhibit the movement of the slide-in unit 3a, 3b. Like above, a movement of the slide-in unit 3a, 3b beyond the first slide-in position B is inhibited until a clear functional state of the switchgear 2a, 2b is guaranteed when the slide-in unit 3a, 3b is removed from the compartment A of the switchgear 2a, 2b.

However, the element 30 alternatively or in addition may have the function of a damper. In this case, the damping element 30, which is another kind of a movement limitation element, in particular creates a back force of more than 50 N if the slide-in unit 3a, 3b is moved at a speed above 10 cm/s. By these measures, a speed is of the slide-unit 3a, 3b is ensured at usual operating forces, which makes sure that one or more steps a) to h) are finished between the first slide-in position B and the second slide-in position C in time. On the other hand, a substantial back force in generated, when said speed is exceeded.

Fig. 6 shows another example of a switchgear 2c with a frame 23b and a door 31 closing an (empty) compartment A of the switchgear 2c. In addition, the

switchgear 2c comprises bus bars 32 of a main power system 6.

Fig. 7 shows the switchgear 2c of Fig. 6 in a state in which the door 31 is opened and the slide-in unit 3c is (partially) inserted in the compartment A of the switchgear 2c forming the protection system 1 d. In this example, the slide-in unit 3c comprises an operating element 33a, which is a handle for the short circuit switch 8c.

Fig. 8 shows another example of a switchgear 2c with a different slide-in unit 3d forming the protection system 1 e. The slide-in unit 3d again comprises a operating element 33a for the short circuit switch 8c. In addition, the slide-in unit 3d comprises a further operating element 33b embodied as a push button, an output device 34a embodied as a signal lamp, an output device 34b embodied as a meter and two front connectors 35a, 35b.

In an advantageous embodiment, the signal lamp 34a in case of insertion of the slide-in unit 3d into the compartment A of the switchgear 2c signals that a movement of the slide-in unit 3d to and over the second slide-in position C shall be delayed until one or more steps a) to d) have been finished positively and that said movement is allowed after said steps a) to d) have been finished positively. For example, the signal lamp 34a lights red until one or more steps a) to d) have not yet been finished and changes to green after said steps a) to d) have been finished positively. In this way, a user of the protection system 1 e gets feedback whether it is allowed to move the slide-in unit 3d beyond the first slide-in position B so as to provide a clear functional state of the protection system 1 e when the slide-in unit 3d is inserted into the compartment A of the switchgear 2c.

Alternatively or in addition, the signal lamp 34a in case of removal of the slide-in unit 3d from the compartment A of the switchgear 2c signals that a movement of the slide-in unit 3d to and over the first slide-in position B shall be delayed until one or more steps e) to h) have been finished positively and that said movement is allowed after said steps e) to h) have been finished positively. Like above, a user of the protection system 1 e gets feedback whether it is allowed to move the slide-in unit 3d beyond the first slide-in position B so as to provide a clear functional state of the switchgear 2c when the slide-in unit 3d is removed from the compartment A of the switchgear 2c.

In a further advantageous embodiment, the front connectors 35a, 35b and/or the push button 34b of the slide-in unit 3d in case of insertion of the slide-in unit 3d into the compartment A of the switchgear 2c are disabled until one or more steps a) to d) have been finished positively and enabled after said steps a) to d) have been finished positively. For example, the control 1 1 a, 1 1 b can be designed to ignore signals from the push button 34b until one or more steps a) to d) have been finished positively. Likewise, the front connectors 35a, 35b can be disconnected from the electric circuit of the slide-in unit 3d until one or more steps a) to d) have been finished positively by means of a relay for example. In this way, use of the slide-in unit 3d is inhibited until a clear functional state of the protection system 1 e is guaranteed when the slide-in unit 3d is inserted into the compartment A of the switchgear 2c.

Alternatively or in addition, the front connectors 35a, 35b and/or the push button 34b of the slide-in unit 3d in case of removal of the slide-in unit 3d from the

compartment A of the switchgear 2c are disabled after said steps e) to h) have been finished positively. Hence, use of the slide-in unit 3d is inhibited when a clear functional state of the protection system 1 e cannot be guaranteed any longer when the slide-in unit 3d is removed from the compartment A of the switchgear 2c. Fig. 9 shows a further alternative embodiment of a protection system 1f. In this example, a cover 36 in case of insertion of the slide-in unit 3e into the compartment A of the switchgear 2c covers a front connector 35a, 35b and/or an operating element 33a, 33b of the slide-in unit 3e until one or more steps a) to d) have been finished positively and releases said front connector 35a, 35b / said operating element 33a, 33b after said steps a) to d) have been finished positively. In this way, again use of the slide-in unit 3e is inhibited until a clear functional state of the protection system 1f is guaranteed when the slide-in unit 3e is inserted into the compartment A of the switchgear 2c. Below the cover 36, the slide-in unit 3e may look like the one of Fig. 8. If a cover 36 is used, disabling the front

connectors 35a, 35b and/or the push button 34b as explained before is not necessary as this task is performed by the cover 36.

Alternatively or in addition, the cover 36 in case of removal of the slide-in unit 3e from the compartment A of the switchgear 2c covers said front connector 35a, 35b / said operating element 33a, 33b after said steps e) to h) have been finished positively.

Like above, use of the slide-in unit 3e is inhibited when a clear functional state of the protection system 1f cannot be guaranteed any longer when the slide-in unit 3e is removed from the compartment A of the switchgear 2c.

In the above examples, the sensors 13a, 13b are built into the switchgear 22a.. 22c. However, this is no necessary condition, and the protection system 1 g, 1 h may comprise portable sensors outside of the switchgear 2d, 2e like this is shown in Figs. 10 and 1 1 .

In the example shown in Fig. 10, a user 37 wears a helmet 38 and a vest 39 which are equipped with external light sensors 13c. The light sensors 13c are connected to a mobile control unit 40, which (wirelessly) communicates with the control unit 1 1 a, 1 1 b of the slide-in unit 3a..3e. Alternatively, the mobile control unit 40 may be connected to the control unit 1 1 a, 1 1 b via the front connectors 35a, 35b. A further external light sensors 13d is mounted on top of the frame 23c of the switchgear 2d. It can be mounted there permanently or temporarily during use of the protection system 1 g. Again, an event may be classified as an arc flash D if the light sensors 13c, 13d detect excessive light. In particular, both a signal from the external light sensors 13c, 13d and an internal current sensor 13b may be evaluated to classify an event as an arc flash D or an arc fault.

In the example shown in Fig. 1 1 , the user 37 wears a fault current detection sensor, which comprises two arm electrodes 41 a, 41 b and a voltage and/or current sensing device 42. Furthermore, the user 37 wears an optional leg electrode 43, which is connected to ground potential. If the user 37 accidentally touches blank conductors of the main power system 6 of the switchgear 2e, a fault current over the arm of the user 37 is detected by the voltage and/or current sensing device 42 and

communicated to the control unit 1 1 a, 1 1 b of the slide-in unit 3a..3e via the mobile control unit 40. In turn, the main circuit breaker 4 may be commanded to switch of the power by the control unit 1 1 a,1 1 b via a communication system of the switchgear 2e / slide-in unit 3a..3e (see the signal line 22 from the control unit 1 1 a, 1 1 b to the main circuit breaker 4 in Fig. 1 ). Alternatively, the short circuit switch 8c may be triggered what leads to switch off of the main circuit breaker 4, too. So, in this embodiment the protection system 1 h comprises an external fault current detection sensor to detect unintentional current over the body of maintenance personnel.

It is noted that the invention is not limited to the embodiments disclosed hereinbefore, but combinations of the different variants are possible. In reality, the protection system 1 a..1 h may have more or less parts than shown in the figures. The protection system 1 a..1 h as well as parts thereof may also be shown in different scales and may be bigger or smaller than depicted. Finally, the description may comprise subject matter of further independent inventions.

It should also be noted that the term "comprising" does not exclude other elements and the use of articles "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims. LIST OF REFERENCE NUMERALS

1 a..1 h protection system

2a..2e switchgear

3a..3e slide-in unit

4 switching device (main circuit breaker)

5 switching device

6 main power system

7a, 7b first main connector

8a. 8c short circuit switch

9a, 9b second main connector

10 auxiliary power system

1 1 a, 1 1 b control unit

12 control input of the short circuit switch

13a. 13d sensor

14 input of the control unit

15 voltage converter

16a, 16b first auxiliary connector

17a, 17b second auxiliary connector

18 first grid connector

19 second grid connector

20 power grid

21 connection between control and sensor

22 connection of communication systems of switchgear and slide-in unit

23a. 23c frame of switchgear

24 rail

25 frame of slide-in unit 26 slider

27 first ground connector

28 second ground connector

29 connector bar

30 movement limitation element (blocking element / damping element)

31 door

32 bus bar

33a, 33b operating element

34a, 34b output device

35a, 35b front connector

36 cover

37 user

38 helmet

39 vest

40 mobile control unit

41 a, 41 b arm electrode

42 voltage and/or current sensing device

43 leg electrode

A compartment

B first slide-in position

C second slide-in position

D arc flash

E grounding slide-in position

L1..L3 phase

Claims

1. Protection system (1 a..1 h), comprising

i) a switchgear (2a..2e) with a compartment (A) for receiving a slide-in unit (3a..3e),

at least one switching device (4, 5),

a main power system (6) connected to the switching device (4, 5) and first main connectors (7a, 7b), which are electrically connected to the main power system (6) and which are arranged in the compartment (A) for the slide-in unit (3a..3e), and

ii) the slide-in unit (3a..3e), which is designed to be inserted in said

compartment (A) of the switchgear (2a..2e), comprising

a short circuit switch (8a. 8c),

second main connectors (9a, 9b), which are electrically connected to the short circuit switch (8a..8c), which are electrically connected to each other in the ON-state of the short circuit switch (8a..8c) and which are electrically disconnected from each other in the OFF-state of the short circuit switch (8a..8c), and

an auxiliary power system (10) for powering a control unit (1 1 a, 1 1 b), which is connected to control input (12) of the short circuit switch (8a..8c), and for powering at least one sensor (13a. 13d), which is connected to an input (14) of the control unit (1 1 a, 1 1 b),

characterized in that

the electric connection to the auxiliary power system (10) of the slide-in unit (3a..3e) is made or established at a first slide-in position (B) of the slide-in unit (3a..3e), and the electrical contact between the first main connectors (7a, 7b) and the second main connectors (9a, 9b) is made or established at a different second slide-in position (C) of the slide-in unit (3a..3e), wherein the first slide-in position (B) is reached before the second slide-in position (C) when the slide-in unit (3a..3e) is inserted into the compartment (A) in the switchgear (2a..2e).

2. Protection system (1 a..1 h) according to claim 1 , characterized in that the at least one sensor (13a. 13d) is built into the switchgear (2a..2e).

3. Protection system (1 a..1 h) according to claim 1 , characterized in that the at least one sensor (13a. 13d) is a portable sensor outside of the switchgear (2a..2e).

4. Protection system (1 a..1 h) according to any one of claims 1 to 3, characterized in that

the at least one switching device (4) in the switchgear (2a..2e) is embodied as a main circuit breaker, which connects an electric circuit downstream of the main circuit breaker to a grid connector (18) of the switchgear (2a..2e) for a power grid (20) in its ON-state and disconnects said electric circuit from said grid connector (18) in its OFF-state and in that

the short circuit switch (8a..8c) of the slide-in unit (3a..3e) is part of the electric circuit downstream of the main circuit breaker when the slide-in unit (3a..3e) is positioned at the second slide-in position (C).

5. Protection system (1 a..1 h) according to any one of claims 1 to 4, characterized in that

a connection between a first ground connector (27) of the switchgear (2a..2e) and a second ground connector (28) of the slide-in unit (3a..3e) is made or established at a third slide-in position (E) and/or

a connection (21 ) between the control unit (1 1 a, 1 1 b) and the at least one sensor (13a. 13d) is made or established at a fourth slide-in position and/or

a connection (22) of a communication system of the switchgear (2a..2e) and a communication system of the slide-in unit (3a..3e) is made or established at a fifth slide-in position, wherein

one or more of the third slide-in position (E), the fourth slide-in position and the fifth slide-in position differ from another and/or differ from the first slide-in position (B) and/or the second slide-in position (C).

6. Protection system (1 a..1 h) according to any one of claims 1 to 5, characterized in that the auxiliary power system (10) is a low voltage system at a voltage of < 48V.

7. Method of inserting a slide-in unit (3a..3e) into an empty compartment (A) of a switchgear (2a..2e), wherein i) the switchgear (2a..2e) has at least one switching device (4, 5), a main power system (6) connected to the switching device (4, 5) and first main

connectors (7a, 7b), which are electrically connected to the main power system (6) and which are arranged in the compartment (A) for the slide-in unit (3a..3e), and wherein

ii) the slide-in unit (3a..3e) has a short circuit switch (8a..8c), second main connectors (9a, 9b), which are electrically connected to the short circuit

switch (8a..8c), which are electrically connected to each other in the ON-state of the short circuit switch (8a..8c) and which are electrically disconnected from each other in the OFF-state of the short circuit switch (8a..8c), and an auxiliary power system (10) for powering a control unit (1 1 a, 1 1 b), which is connected to control input (12) of the short circuit switch (8a..8c), and for powering at least one

sensor (13a. 13d), which is connected to an input (14) of the control unit (1 1 a, 1 1 b), comprising the steps of

moving the slide-in unit (3a..3e) to a first slide-in position (B) and from the first slide-in position (B) to a different second slide-in position (C),

characterized in that

the electric connection to the auxiliary power system (10) of the slide-in unit (3a..3e) is made or established at the first slide-in position (B) of the slide-in unit (3a..3e), and the electrical contact between the first main connectors (7a, 7b) and the second main connectors (9a, 9b) is made or established at the second slide- in position (C) of the slide-in unit (3a..3e), wherein the first slide-in position (B) is reached before the second slide-in position (C) when the slide-in unit (3a..3e) is inserted into the compartment (A) in the switchgear (2a..2e).

8. Method according claim 7, characterized in that

during insertion of the slide-in unit (3a..3e) into the compartment (A) of the switchgear (2a..2e) at or after the first slide-in position (B), but before second slide-in position (C)

a) a boot sequence of the control unit (1 1 a, 1 1 b) is performed and finished and/or b) a connection (21 ) is set up between the control unit (1 1 a, 1 1 b) and the at least one sensor (13a. 13d) and/or

c) a connection (22) is set up between a communication system of the switchgear (2a..2e) and a communication system of the slide-in unit (3a..3e) and/or d) a check of a serviceability of the short circuit switch (8a..8c) is performed and/or in that

during removal of the slide-in unit (3a..3e) from the compartment (A) of the switchgear (2a..2e) at or after the second slide-in position (C), but before first slide-in position (B)

e) a shut down sequence of the control unit (1 1 a, 1 1 b) is performed and finished and/or

f) a connection (21 ) between the control unit (1 1 a, 1 1 b) and the at least one sensor (13a. 13d) is closed and/or

g) a connection (22) between a communication system of the switchgear (2a..2e) and a communication system of the slide-in unit (3a..3e) is closed and/or

h) a check of a serviceability of the short circuit switch (8a..8c) is performed.

9. Method according claim 8, characterized in that an output device (34a, 34b) signals that

in case of insertion of the slide-in unit (3a..3e) into the compartment (A) of the switchgear (2a..2e) a movement of the slide-in unit (3a..3e) to and over the second slide-in position (C) shall be delayed until one or more steps a) to d) have been finished positively and that the output device (34a, 34b) signals that said movement is allowed after said steps a) to d) have been finished positively and/or

in case of removal of the slide-in unit (3a..3e) from the compartment (A) of the switchgear (2a..2e) a movement of the slide-in unit (3a..3e) to and over the first slide- in position (B) shall be delayed until one or more steps e) to h) have been finished positively and that the output device (34a, 34b) signals that said movement is allowed after said steps e) to h) have been finished positively.

10. Method according claim 8 or 9, characterized in that a movement limitation element (30), which is embodied as a blocking element,

in case of insertion of the slide-in unit (3a..3e) into the compartment (A) of the switchgear (2a..2e) stops the movement of the slide-in unit (3a..3e) between the first slide-in position (B) and the second slide-in position (C) until one or more steps a) to d) have been finished positively and that the blocking element (30) releases the slide-in unit (3a..3e) after said steps a) to d) have been finished positively and/or in case of removal of the slide-in unit (3a..3e) from the compartment (A) of the switchgear (2a..2e) stops the movement of the slide-in unit (3a..3e) between the second slide-in position (C) and the first slide-in position (B) until one or more steps e) to h) have been finished positively and that the blocking element (30) releases the slide-in unit (3a..3e) after said steps e) to h) have been finished positively.

1 1 . Method according any one of claims 8 to 10, characterized in that a cover (36) in case of insertion of the slide-in unit (3a..3e) into the compartment (A) of the switchgear (2a..2e) covers an front connector (35a, 35b) and/or an operating element (33a, 33b) of the slide-in unit (3a..3e) until one or more steps a) to d) have been finished positively and that the cover (36) is released after said steps a) to d) have been finished positively and/or

in case of removal of the slide-in unit (3a..3e) from the compartment (A) of the switchgear (2a..2e) covers said front connector (35a, 35b) / said operating element (33a, 33b) after said steps e) to h) have been finished positively.

12. Method according any one of claims 8 to 1 1 , characterized in that a front connector (35a, 35b) and/or an operating element (33a, 33b) of the slide-in unit (3a..3e)

in case of insertion of the slide-in unit (3a..3e) into the compartment (A) of the switchgear (2a..2e) are disabled until one or more steps a) to d) have been finished positively and enabled after said steps a) to d) have been finished positively and/or in case of removal of the slide-in unit (3a..3e) from the compartment (A) of the switchgear (2a..2e) are disabled after said steps e) to h) have been finished positively.

13. Method according to any one of claims 8 to 12, characterized in that

one or more steps a) to d) have been finished before the slide-in unit (3a..3e) reaches the second slide-in position (C) when it is moved at a speed of 10 cm/s and/or

one or more steps e) to h) have been finished before the slide-in unit (3a..3e) reaches the first slide-in position (B) when it is moved at a speed of 10 cm/s.

14. Method according to any one of claims 8 to 13, characterized in that a movement limitation element (30), which is embodied as a damping element, creates a back force of more than 50 N if the slide-in unit (3a..3e) is moved at a speed above 10 cm/s.