Three-phase switchgear with single-phase equipment in one enclosure

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a three phase switchgear or control gear for low voltage, medium voltage or high voltage use with a substation.BACKGROUND OF THE INVENTION

[0002] CN105655912A describes an environment-friendly gas insulation switch cabinet which comprises a cabinet body. A sealed box body is arranged on the upper portion of the cabinet body. Three circuit breakers are arranged in the sealed box body side by side. Each circuit breaker comprises a U-shaped connection bus and a supporting frame, wherein a copper insert is arranged on the top of the supporting frame, the two sides of the connection bus are connected with a wire inlet insulator and a bus insulator, the connection bus is fixed to the copper insert, an arc extinguish chamber is arranged at the bottom of the copper insert, a pull rod is arranged at the bottom of the arc extinguish chamber, the bottom of the pull rod is connected with a circuit breaker operation mechanism through a rotating shaft, the upper portion of the pull rod is connected with a touch base through a soft connector, and a three-station isolation switch controlled by a three-station operation mechanism is arranged below the touch base. It is descried that the environment-friendly gas insulation switch cabinet is reasonable in structure, high in modularization degree, safe and reliable to operate, low in running cost, convenient to overhaul, long in service life, high in environment adaptability, green and environmentally friendly.

[0003] EP0678956A1 describes a combined current and voltage sensor for a high voltage switchgear panel has a housing made from age-hardening castable material. At one end, the housing has a cavity, in the bottom of which is a contact element. The cavity has a lid made from insulating material. Between the lid and the contact element is an elongated high ohmage resistor, used as a voltage sensor. The contact element is connected to a conductor embedded in the housing and at the other end of the conductor is a circuit breaker. A Rogowski coil around this conductor acts as the current sensor.

[0004] In state-of-art switchgear and control gear (also called controlgear) designs the primary circuits of the three phases are arranged in groups for each feeder circuit, together forming a three phase feeder circuit. There is one common drive mechanism for the circuit breaker, one common drive for the disconnector and one common drive for the earthing switch for all three phases.

[0005] This arrangement can be problematic for handling and maintenance purposes, and has associated risks of internal arc faults in the complete power circuit.

[0006] There is a need to address these issues.SUMMARY OF THE INVENTION

[0007] Therefore, it would be advantageous to have a better design of a switchgear or control gear.

[0008] The object of the present invention is solved with the subject matter of the independent claim, wherein further embodiments are incorporated in the dependent claims.

[0009] According to the invention, there is provided a three phase switchgear or control gear, according to independent claim 1.

[0010] In an example, for the first phase the second phase and the third phase, sets of bushings are used to connect the cable connections for each phase to components for each phase housed in the first compartment.

[0011] In an example, current and voltage sensors are embedded into each of the three sets of bushings.

[0012] In an example, current and voltage sensors are embedded in each of the three single phase circuit breaker poles.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Exemplary embodiments will be described in the following with reference to the following drawings: Fig. 1 shows an example of a three phase switchgear or control gear, not covered by claims; Fig. 2 shows an example of a three phase switchgear or control gear, according to the invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0014] Figs. 1-2 show examples of a switchgear or control gear for operation in a low voltage, medium voltage or high voltage substation.

[0015] One example relates to a three phase switchgear or control gear that comprises at least one compartment 3, 9, 10, 12, a plurality of components for a first phase, a plurality of components for a second phase, and a plurality of components for a third phase. The plurality of components for the first phase the second phase and the third phase each comprise a main busbar 8, a three position linear or rotational movement disconnector switch 2, a single phase circuit breaker pole 4, and a cable connection 7.

[0016] According to the invention, the three phase switchgear or control gear comprises a first compartment, a second compartment and a third compartment.

[0017] For the first phase the second phase and the third phase the main busbar, the three position linear or rotational movement disconnector switch, and the single phase circuit breaker pole are housed in the first compartment 9.

[0018] According to the invention, the three cable connections are housed in the second compartment 10.

[0019] According to the invention, the second compartment comprises a door or removable wall section. The switchgear or control gear is configured such that an operator can gain access to the inside of the second compartment via the door or removable wall section whilst the switchgear or control gear is in operation.

[0020] According to the invention, the second compartment is separated from the first compartment by an arc proof segregation.

[0021] According to an example, for the first phase the second phase and the third phase, sets of bushings 5 are used to connect the cable connections for each phase to components for each phase housed in the first compartment.

[0022] According to an example, current and voltage sensors are embedded into each of the three sets of bushings.

[0023] According to the invention, the plurality of components for the first phase the second phase and the third phase each comprises a circuit breaker single phase actuator 1.

[0024] According to the invention, the three circuit breaker single phase actuators are housed

[0025] in the third compartment 12.

[0026] According to the invention, the third compartment within which the three circuit breaker single phase actuators are housed comprises a door or removable wall section. The switchgear or control gear is configured such that an operator can gain access to the inside of the third compartment via the door or removable wall section whilst the switchgear or control gear is in operation.

[0027] According to the invention, the third compartment is separated from the first compartment by an arc proof segregation 11.

[0028] According to an example, current and voltage sensors are embedded in each of the three single phase circuit breaker poles.

[0029] Thus, a new substation development is provided, where three phase switchgear or control gear have arrangements of the primary circuits that separate phase by phase. This enables the drives of all switching devices to be designed as single phase only and thus avoiding the need for a parallel arrangement. Having the drives per single phase (i.e. tripling the number of needed drives) the primary circuits of each phase can be arranged in much more compact way bringing substantial material and assembly work savings, while the phase-to-phase distance increases significantly. There is also improved behavior of the switchgear or control gear in many operational aspects. The new design is applicable to both human operated switchgear and control gear as well as the switchgear or control gear with unmanned operation and maintenance.

[0030] To put this another way, all the current state-of-art switchgear and control gear design have primary circuits that are grouped per feeder. However, for the new design described here it has been found to be advantageous for the switchgear or control gear to move to phase by phase arrangement on the primary circuits. This arrangement reduces the number of components on primary circuits to a minimum, decreases the risk of internal arc faults in the complete power circuit and allows modularization of the components to single phase switching device plus drive subassemblies. This facilitates better handled by human or automation maintenance systems (lower weight and dimensions compared to today's three phase devices).

[0031] Continuing with the figures, specific features are now described.

[0032] Fig. 1 shows a detailed example of a three phase switchgear or control gear, where for ease of reference the following features shown are listed: 1. Circuit breaker phase actuator and auxiliaries; 2. Three position disconnector with single phase actuator and auxiliaries; 3. Arc proof enclosure; 4. Single phase circuit breaker pole; 5. Bushing with embedded current and voltage sensors; 6. Earth copper; 7. Cable connections copper; 8. Main busbars; 9. Main space for circuits (this can include an automation maintenance system); 10. Cable compartment segregated from the main space for circuits 9, with sidewalls for segregation between feeders, accessible after removing a removable cover or opening doors (shown as the bottom wall in Fig. 1).

[0033] As shown in fig. 1 the primary circuits of the different phases of a three phase switchgear or control gear are in a phase by phase arrangement, rather than per feeder groups. The following advantages can be gained by separating the phases: 1.) Limiting the number of components and the total length of the primary circuits to a minimum; 2.) Decreasing the risk of phase-to-phase internal arc faults by increasing the distance between phases, while keeping a small footprint of the switchgear or control gear; 3.) Increased phase to phase distance results in lower mechanical stress on the primary circuits in case of a short circuit; 4.) Increased phase to phase distance results in lower dielectric stress on the insulation components; 5.) Switchgear or control gear footprint can be significantly reduced by this arrangement; 6.) The heat ventilation can be improved compared to today state-of-art, allowing better utilization of copper 7.) Ability to switch single phase loads.

[0034] The new switchgear or control gear arrangement of phase by phase opens space for redesign of the main switching devices, that can be modularized to a single phase switching device plus drive subassemblies. This can be better handled by human or automation maintenance systems (lower weight and dimensions compared to today three phase devices).

[0035] Many components used in existing switchgear or control gear arrangements can be reused in the new arrangement. A three position disconnector switch is shown in Fig. 1, however it withdrawal breaker operating principle is a viable alternative option.

[0036] The feeder circuit in each phase has a short T-off from the main busbar, a three position disconnector switch, a circuit breaker and cable connection bars. While the main busbars and switching devices can be located in one big compartment common for all feeders, the cable connections are located in a cable termination box that is separate for each feeder. This facilitates access to the cable terminations for human operators, while the switchgear or control gear is in operation.

[0037] The cable compartment segregation from the main circuit space provides a minimum IP1X degree of protection for the operator. Each segregated cable compartment is equipped with flaps for exhaust of the hot gases in case of internal arc or a quick acting active arc fault protection can be used for avoiding pressurizing of the cable compartments. Each cable compartment enclosures can then be arc proof towards the main circuit's main space as well as towards outer space.

[0038] The current and voltage measurement is provided preferably by current and voltage sensors, that can be embedded in bushings segregating the main circuit space from the cable compartment.

[0039] As shown in Fig. 1, current and voltage measurement is provided via current and voltage sensors embedded in bushings. However, the current and voltage measurement can be provided by current and voltage transformers.

[0040] The Fig.1 is showing the main circuit's compartment common for all three phases. Providing earthed metallic or insulating material segregation between phases further increases the protection against internal arc between phases.

[0041] Fig.1 show the cable compartment box 10 embedding all three phases for each feeder. The cable compartment can be further segregated per phase to increase protection against internal arc between phases.

[0042] Fig.1 shows the cable compartment that is arc proof separated from the main circuit space. However, the cable compartment does not have to be separated from the main circuit space.

[0043] It is also to be noted that the rotational three position disconnector switches shown in Fig.1 can be replaced with a linear three position disconnector switches.

[0044] However, the withdrawable operating principle can be applied, i.e. instead of having a disconnector switch device the circuit breaker pole can be designed as withdrawable and the movement of the pole does the disconnecting.

[0045] In Fig. 1, the current and voltage sensors are shown embedded in the bushings. However, these components can be designed as stand alone as well, and positioned in the cable compartment or in the main circuits compartment. Also, the current and voltage sensors can be embedded in a circuit breaker pole.

[0046] Fig.1 shows a switchgear or control gear with unmanned operation, with primary circuits in the main circuits' space accessible for human operator only when deenergized.

[0047] As shown in Fig.2 the same principles as described with respect to Fig. 1 are implemented, for a switchgear or control gear that is human operated and maintained. A safe space 12 is provided as an additional compartment within which the circuit breaker single phase actuators and auxiliaries are housed, with this safe space 12 segregated from the main compartment by an additional arc proof segregation 11. Thus, further functionality is provided by adding an arc proof segregation covering the main circuits' compartment for maintenance and operation personnel. The bottom wall of the cable termination compartment, shown at the bottom of Fig. 2, can be a removable cover or doors enabling access by human operator.

[0048] The primary circuit can include other components and devices not described in Fig.1, such as earthing switch, voltage indication, surge arrestors, UFES, IS-limitors, contactors, load-break switches, fuses. The described principles of phase by phase separation is kept in that case.

[0049] It is also to be noted that the switchgear or control gear outer envelope does not have to be arc proof if the switchgear or control gear is located in a substation denying human access when the switchgear or controlgear is in operation.

Claims

1. A three phase switchgear or control gear, comprising: - a first compartment (3, 9); - a second compartment (10); - a third compartment (3, 12) - a first plurality of components for a first phase; - a second plurality of components for a second phase; and - a third plurality of components for a third phase; wherein, each of the first plurality of components the second plurality of components and the third plurality of components comprise a main busbar (8), a three position linear or rotational movement disconnector switch (2), a single phase circuit breaker pole (4), a circuit breaker single phase actuator (1), and a cable connection (7); wherein for the first phase the second phase and the third phase the main busbar, the three position linear or rotational movement disconnector switch (2), and the single phase circuit breaker pole (4) are housed in the first compartment (3, 9); wherein the cable connection for the first phase the cable connection for the second phase and the cable connection for the third phase are housed in the second compartment (10); wherein the second compartment comprises a first door or removable wall section, and wherein the switchgear or control gear is configured such that a human operator can gain access to cable terminations for the cable connection for the first phase the cable connection for the second phase and the cable connection for the third phase an inside of the second compartment via the first door or removable wall section whilst the switchgear or control gear is in operation, wherein the second compartment is separated from the first compartment by a first arc proof segregation; and wherein the circuit breaker single phase actuator for the first phase the circuit breaker single phase actuator for the second phase and the circuit breaker single phase actuator for the third phase are housed in the third compartment (3, 12); wherein the third compartment comprises a second door or removable wall section, and wherein the switchgear or control gear is configured such that the human operator can gain access to an inside of the third compartment via the second door or removable wall section whilst the switchgear or control gear is in operation,wherein the third compartment (3, 12) is separated from the first compartment (3, 9) by a second arc proof segregation (11).

2. Switchgear or control gear according to claim 1, wherein for the first phase the second phase and the third phase, sets of bushings (5) are used to connect the cable connections for each phase to components for each phase housed in the first compartment.

3. Switchgear or control gear according to claim 2, wherein current and voltage sensors are embedded into each of the three sets of bushings.

4. Switchgear or control gear according to any of claims 1-3, wherein current and voltage sensors are embedded in each of the three single phase circuit breaker poles.