MCset – Air Insulated Switchgear with SF6 CB

General about MCset

MCset is Schneider Electric‘s AIS – Air Insulated Switchgear (indoor metal-enclosed device) intended for the MV section of HV/MV substations and high power MV/MV substations up to 24kV.

Main component of MCset is circuit breaker which is SF6 type.

MCset – Air Insulated Switchgear offers:

• Pre-engineered and adaptable solutions tailored to your customer’s requirements
• Significantly reduced maintenance
• Local support centres throughout the world.

Technical characteristics

The values below are given for the normal operating conditions as defined in IEC 62271-200 and 62271-1.

IAC (internal arc classification)

The metal enclosed switchgear may have different types of accessibility on the various sides of its enclosure. For identification purposes concerning the different sides of the enclosure, the following code shall be used (according to the IEC 62271-200 standard):

A – restricted access to authorised personnel only
F – access to the front side
L – access to the lateral side
R – access to the rear side.

Functional unit

A functional unit consists of all of the equipment in the main and auxiliary circuits which together provide a protection function.

Each functional unit combines all of the components which are required to fulfil function: the cubicle, and the protection, monitoring and control system (including the withdrawable live part).

Accessibility of the MV compartments

There are two types of compartments:

Interlock-controlled accessible compartment which contains withdrawable MV part (circuit breaker, contactor) compartment for AD/RHC/RHB/CL units, and

Tool-based accessible compartments which contains cable compartment, main busbar for the AD/RHC/ CL/GL/DI units, busbar compartment for the RHB, bottom busbar compartment for the CL/GL units and fixed bridge compartment for the GL unit.

Structure of an MCset switchboard

MCset switchboards are made up of several interconnected functional units. The power connections are made between the functional units within a switchboard via a single busbar.

The electrical continuity of all of the metal frames is provided by the connection of each functional unit’s earthing busbar to the switchboard’s main earthing circuit. Low voltage wiring trays are provided in the switchboard above the low voltage control cabinets.

Low voltage cables can enter the switchboard through the top or bottom of each functional unit.

Functions

The cubicle is of LSC2B (Loss of Service Continuity Category) type as defined by IEC standard 62271-200, in other words the medium voltage parts are compartmented using metal partitions (PM class) which are connected to earth and which separate:

1. The busbars
2. The withdrawable part (circuit breaker, fuse-contactor, disconnector truck or earthing truck)
3. MV connections, earthing switch, current sensors and voltage transformers as required.

MCset guarantees a high level of protection of people; when a compartment containing a main circuit is open, the other compartments and/or functional units may remain energised.

The low voltage auxiliaries and monitoring unit are in a control cabinet separated from the medium voltage section.

Incomer or feeder – AD type cubicles

MV/LV devices

1. Busbars for cubicle interconnection
2. Main switching device
3. MV connections by cables accessible from the front face
4. Earthing switch
5. Current sensors
6. Voltage Transformers (optionally equipped with withdrawable fuses)
7. LV control cabinet – Low voltage auxiliaries and the protection, monitoring and control unit are in a control cabinet which is separated from the medium voltage part

CL – GL type cubicles – Line-up bussectioning

MV/LV devices

1. Busbars to connect the bussectioning functional unit with other switchboard functional units
2. Main switching device
3. Current sensors
4. Voltage Transformers (optionally equipped with withdrawable fuses)
5. LV control cabinet – Low voltage auxiliaries and protection, monitoring and control unit are in one control cabinet, separated from the medium voltage part

TT type cubicles – Metering – Busbar earthing

MV/LV devices

1. Busbars to connect the TT functional unit with other switchboard cubicles
2. Earthing switch
3. Voltage Transformers (optionally equipped with withdrawable fuses)
4. LV control cabinet – Low voltage auxiliaries and the protection, monitoring and control unit are in a control cabinet which is separated from the medium voltage part

DI type cubicles – Fuse-switch feeder

MV/LV devices

1. Busbars to connect the DI functional unit with other switchboard cubicles
2. Switch – earthing switch
3. MV fuses
4. LV control cabinet – Low voltage auxiliaries and protection, monitoring and control unit are in one control cabinet, separated from the medium voltage part

MCset medium voltage switchgear up to 24kV (VIDEO)

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Seismic type test performed on MCset (VIDEO)

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Reference: MCset and PIX AIS switchgears catalogu 2010 – Schneider Electric