Design

A 3KF switch disconnector with fuses consists of an operating mechanism module, three or four switching poles and a handle to operate the switch disconnector.

Handles

The direct operating mechanism version of the handle is mounted directly on the switch disconnector. It can also be supplied in the form of a door-coupling rotary operating mechanism for actuation of the switch disconnector outside the control cabinet door. The handle is available in gray, or colored red/yellow for use as an EMERGENCY STOP switch.

Commonly used switch disconnector variants comprising basic unit and handle are available as complete assemblies.

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Handle either as direct operating mechanism or door-coupling rotary operating mechanism

Position of operating mechanism modules

To allow optimum utilization of the available installation space, units with front operating mechanisms can be supplied with the operating mechanism module in various positions – mounted on the left-hand side of the 3KF switch disconnector with fuses or in the center between the switching poles.

On units with lateral operating mechanisms, the operating mechanism module is positioned on the right or left-hand side of the 3KF switch disconnector with fuses.

Number of poles/application

Front operating mechanism, side

Front operating mechanism, center

Lateral operating mechanism, left

Lateral operating mechanism, right

3-pole

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4-pole

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Additional poles

All sizes of the 3KF switch disconnectors with fuses can be retrofitted with additional poles on a modular basis.

When installing additional poles, it is important to note that only a 3-pole 3KF switch disconnector with fuses may be retrofitted with an additional switching pole with contact system (4th contact element).

Additional poles (4th contact element, N or N/PE terminal) must always be mounted directly adjacent to the switch disconnector on the left or right, therefore, it is not permissible to install an auxiliary switch module between the basic unit and an additional pole for size 1.

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Installation of an additional pole

Available versions

4th contact element:

The 4th contact element includes a contact system and is identical to the poles installed at the factory. It can be installed to upgrade a 3-pole switch disconnector to a disconnector with 4 poles.

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4th contact element as an additional pole

N terminal (neutral conductor terminal):

The N terminal does not include a contact system. A jumper can be removed in order to interrupt the electrical connection between the two terminals. An N terminal can be installed to add a non-switching N pole to a 3-pole disconnector.

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N terminal as non-switching pole

N/PE terminal:

The N/PE terminal is identical to the neutral conductor terminal. However, the electrical connection between the two terminals is permanent and cannot be interrupted by removal of a jumper. The N/PE terminal is normally deployed for applications in which it is vital to ensure that this connection can never be interrupted.

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N/PE terminal with permanent connections

Auxiliary switches

Auxiliary switches allow remote interrogation of the contact position of the 3KF switch disconnector with fuses.

Installation of auxiliary switches for size 1

The auxiliary switches used for size 1 are microswitches (changeover contacts), which can be snapped into an auxiliary switch module. This auxiliary switch module is mounted on the side of the switch disconnector with fuses in the same way as an additional pole. A maximum of two microswitches can be installed in each auxiliary switch module.

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Auxiliary switch with auxiliary switch module for size 1

Installation of auxiliary switches for sizes 2 to 5

With sizes 2 to 5, the auxiliary switches are directly attached to the operating mechanism module. The auxiliary switch with the leading switch function is always installed in the right-hand mounting location. The other locations are provided for simultaneously switching with the main contacts.

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Auxiliary switches directly attached to the operating mechanism module with sizes 2 to 5. The leading auxiliary switch is highlighted in the drawing.

Switching instants of auxiliary switches

The auxiliary switches can operate either simultaneously with the main contacts or function as leading switches with all sizes.

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One of the possible functions of leading auxiliary switches is to disconnect the circuit with the assistance of a higher-level switching device, such as a circuit breaker, before the main contacts of the 3KF switch disconnector with fuses open.

With size 1, the selection of the appropriate auxiliary switch module determines whether the switching instant will be leading or simultaneous.

With sizes 2 to 5, the switching instant is determined by the selection of the mounting location for the auxiliary switch on the operating mechanism module.

Test function for auxiliary switches

The test function allows a wiring check to be performed on the auxiliary switches without necessitating closure of the main contacts of the 3KF switch disconnector with fuses. The test function can be used as part of the commissioning process.

The test function is activated by turning the handle of a direct operating mechanism in the OFF position by 25° in the counter-clockwise direction. The handle must be turned 90° in the clockwise direction in order to switch the main contacts.

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The auxiliary switch module including test function must be used for size 1. With sizes 2 to 5, all installed auxiliary switches are switched when the test function is activated.

Types of mounting

All 3KF switch disconnectors with fuses are designed for floor mounting. To ensure that the switch can be flexibly adapted to the relevant installation conditions, the mounting bracket can be rotated through 90° with size 2 or larger.

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Floor mounting method

Size 1 can be snapped onto a standard mounting rail (TH35 according to EN 60715) as an alternative mounting method.

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Mounting on a standard mounting rail

Locking functions

3KF switch disconnectors with fuses can be locked by up to three padlocks to prevent unauthorized switch operation.

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Locking functions involving one or more padlocks

Electrical connection

3KF switch disconnectors with fuses feature different connection options.

Box terminals

Box terminals for size 1 (rated currents 32 A to 80 A) are designed to allow the speedy connection of stripped conductors.

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Connection via box terminals

Flat terminals

Sizes 2 to 5 (rated currents 125 to 800 A) are available with flat terminals for the connection of cable lugs or busbar systems.

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Connection via flat terminals

Flat terminals at rear

Sizes 1 to 2 (rated currents up to 125 A) are available with rear flat terminals for the connection of cable lugs or busbar systems.

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Connection via rear flat terminals

Terminal covers and phase barriers

Terminal covers and phase barriers can be supplied for 3KF switch disconnectors with fuses with flat terminals.

Terminal covers

Terminal covers can be installed to provide touch protection for all terminals.

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Terminal covers

Phase barriers

When long, non-insulated cable lugs are used, phase barriers provide enhanced protection against arcing.

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Phase barriers

Fuse monitoring

Fuse monitoring is used to detect, indicate and report faults. The fuse monitoring can be mounted on the side of each 3KF switch disconnector with fuse and away from the 3KF on a standard mounting rail or mounting plate.

The fuse monitoring is equipped with a floating changeover contact for remote signaling of tripped fuses. Locally, the tripped fuse is displayed for each phase by LEDs.

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Fuse monitoring on the 3KF