Medium-Voltage Load Interrupter Switches

Applications for Medium-Voltage Load Interrupter Switches

Spike’s LIS medium-voltage load interrupter switches provide safe, reliable switching and fault protection. The metal enclosed assembly – consisting of a 5kV – 38kV switch, bus and fuses – is designed to meet the requirements of a wide range of industries such as healthcare, data center, industrial, utility, mining and commercial.

Metal enclosed LIS Load Interrupter Switchgear Spike LIS Load Interrupter Switchgear is an integrated assembly of switches, bus and fuses that is constructed for medium voltage circuit protection. All major components are tested to the highest allowed voltage, establishing one source of responsibility for the equipment’s performance and ensuring high standards in quality, coordination, reliability and service. A complete line from a single switch to multiple switches integrated together on a common bus are available.

Spike Electric’s medium-voltage load interrupter switches provide safe, reliable switching and fault protection.

Load Interrupter Switch Features

Enclosures are available in both outdoor and indoor standard painted Ansi gray. Custom colors are available upon request. Standard standalone single switches do not come with modular expansion bus capabilities to connect future switches together.

• 5kV – 38 Kv voltage class
• 600A & 1200A continuous load interrupting ratings, custom switches up to 5000A.
• Main bus is rated for 600 amperes, 3000-ampere bus is also available
• Non-fused or fused with current limiting or boric acid-type fuses
• Manual or motor operated Indoor or outdoor non-walk-in enclosures
• Single switches and transformer primary switches
• Duplex load break switch arrangements for selection of alternate feeds
• Lineups with main bus
• Standard arrangements with automatic transfer control systems (two sources feeding one bus or two sources feeding two buses on a split bus with tie switch)

Standard design configurations for:

• NEMA pads for cable lugs
• Kirk Key Interlock Provisions available Disc Handle with Lock Out Tag Out Provisions
• 8”x16” High Impact Viewing Window that permits full

Load Interrupter Switch Fuses

“AC” fuses are current limiting fuses of the backup type. These fuses can interrupt all currents from their maximum interrupting current (I1) to currents as low as the minimum interrupting current (I3) mentioned in the corresponding lists of each fuse model.

Fuse Application

Its application is for protection against electrical failures of great magnitude. In the case of this type of failure, the fuse considerably reduces thermal and magnetic influences, providing excellent protection for electrical equipment, due to its current limiting effect.

For its application, the corresponding standards mentioned below must be taken into consideration. Mainly it is necessary to provide that the equipment to be protected also has secondary protections for those low-intensity electrical failures, which cannot be seen by a fuse, such as, for example, ground faults and / or any other fault in the area of the current I3. As these faults usually have their origin at the low voltage site of the transformer. It can be considered that the protection of the low voltage side will usually be enough to eliminate any type of low over currents at the primary site.

These fuses are used for the protection of transformers, potential transformers, control transformers, motors, capacitors, cables and distribution systems.

For proper coordination with other fuses of our brand in the same distribution network, a coordination factor of at least 1,6 times its rated current is recommended. This means that a fuse of 100 A rated current requires a fuse of 63 A or less downstream and a fuse of 160 A or higher upstream.

Each fuse has a striker and indicator system, for which the company obtained the corresponding patent. The striker system differs from an indicating system, in the sense that it operates with a greater mechanical force.

When the Fuse Element Operates

When the fuse element operates, e. g. due to the influence of a fault current, of sufficient magnitude, the striker system is activated, making the striker pin exit by approximately 1.18in. with a mechanical force of at least 50 N (up to 120 N). The striker system has the purpose of activating the three-phase trip mechanism of the disconnector in the event of a failure in any of the three phases (fuses) carried by the disconnector, in order to prevent the electrical system from continuing to operate in two phases, provided the disconnector has such a three-phase trip mechanism that can be activated by the fuse striker system.

Apart from this it gives a visual warning that the fuse has operated. It can also be used to indicate remotely that the fuse has operated, through use, e.g. of limit switches, ensuring that the contact between the striker system and the activation is not in a direct manner, but by using an insulated rod or other device, which guarantees the minimum insulating needs.

Care During Installation

When installing the fuse in the corresponding fuse holder, care must be taken that the striker system is aligned with the eventual trip system of the disconnector and that this is sensitive enough for the striker system to operate.

Many times, the lack of maintenance or excessive contamination, causes the disconnector trip system not to operate or a greater mechanical force is required to activate it. In this case, the fuses with the striker system of the strongest mechanical force must be used.