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MES-Series 2.4kV-38kV Air Insulated Load Interrupter Switchgear (LIS)

Air Insulated Load Interrupter Switchgear for Use as Fused Switch Based Switchgear

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   Power Solution Information

The APT MES-Series Medium Voltage Load Interrupter Switchgear (LIS) utilizes state-of-the-art three phase gang-operated load break switching to achieve safe disconnection of loads from a power system. The MES-Series LIS is available either unfused or fused for overcurrent protection in simple, low cost protection applications.

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MES-SERIES

Load Interrupter Switchgear (LIS)

2.4kV - 38kV Air Insulated Load Break Switchgear

SF6-free, three-phase load break switching designed for safe load disconnection, visible isolation, and optional fused overcurrent protection.

MES-Series air insulated load interrupter switchgear
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Voltage Range
2.4kV - 38kV
Switch Rating
200A / 600A / 1200A*
Momentary Rating
40kA
BIL Rating
60kV - 150kV
Enclosures
NEMA 1 & 3R
Insulation
Open Air / SF6-Free
*1200A available up to 15kV.

Key Specifications

Voltage
2.4kV - 38kV
Momentary
40kA
Switch Rating
200A / 600A / 1200A*
BIL
60kV - 150kV
Enclosures
NEMA 1 & 3R
Insulation
Open Air / SF6-Free
*1200A available up to 15kV.

Overview

The MES-Series is medium-voltage, air-insulated load interrupter switchgear designed for safe three-phase load switching and visible isolation.

Available in fused or unfused configurations, the MES-Series can provide straightforward load disconnection alone or incorporate current-limiting fuses for overcurrent protection.

Its SF6-free, open-air design is available for indoor or outdoor installations and can be applied to utility, generator, transformer, and motor circuits.

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Standard Construction

MES-Series load interrupter switchgear construction
  1. 01 Carbon Steel, ANSI 61 Gray
  2. 02 NEMA 1 or NEMA 3R Enclosure
  3. 03 Silver-Plated Copper Bus
  4. 04 Visible Three-Blade Air Disconnect

Final configuration may vary by project requirements.

Why It Matters

Visible Isolation

Viewing windows provide a clear view of all three disconnect blades.

SF6-Free Switching

Open-air insulation eliminates the need for SF6 switch insulation.

Flexible Protection

Available fused or unfused to match the protection requirements of the system.

Application Flexibility

Supports utility, generator, transformer, and motor switching applications.

How It Works

MES-Series load interrupter switchgear diagram Electrical power travels from the source through a three-phase load break switch and optional overcurrent fuses before supplying the connected load. SOURCE LOAD BREAK SWITCH OPTIONAL FUSES LOAD SWITCHING + VISIBLE ISOLATION OVERCURRENT PROTECTION

The gang-operated load break switch provides three-phase switching and isolation from the connected source. A viewing window allows the switch-blade position to be visually confirmed, while optional current-limiting fuses can provide integral overcurrent protection.

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MES-Series load interrupter switchgear

Need Help Selecting the Right Configuration?

Not sure which voltage, switch rating, enclosure, or fuse configuration your application requires? Our sales team can help you select the right MES-Series Load Interrupter Switchgear for your project.

Voltage Switch Rating Enclosure Fuse Protection

Our team can help with:

  • Application review
  • Fused or unfused configurations
  • Indoor or outdoor enclosure selection
  • Project-specific switchgear configurations
Talk to a Product Specialist

Technical Specifications

System Voltage
2.4kV - 38kV, 3Ø
Switch Rating
200A, 600A & 1200A*
Momentary Rating
40kA
BIL Rating
60kV - 150kV
Insulation Type
Open Air Insulated / SF6-Free
Mechanism Types
Snap Action K / Stored Energy A
Overcurrent Protection
Optional Current-Limiting Fuses
Fuse Rating
50A - 1200A
Enclosures
NEMA 1 Indoor / NEMA 3R Outdoor
Main Bus
Silver-Plated Copper
Access
Front Access Only
Air Insulated Pole Spacing
5.9 in. - 14.1 in.
Auxiliary Contacts
None, 3 N.O. / 3 N.C., or 4 N.O. / 4 N.C.
Cable Pull Section
Optional 12 in.
Typical Dimensions
100"H × 40"W × 41"D**
Visible Disconnect
Lexan Viewing Window for All Three Switch Blades

*1200A switch rating available up to 15kV.

**Typical dimensions shown for designs up to 15kV. Final dimensions vary by configuration.

Applications

Common medium-voltage switching and protection applications for the MES-Series.

Utility Source Switching

Utility source disconnection with optional integral fused overcurrent protection.

Generator Source Switching

Generator source disconnection with optional integral fused overcurrent protection.

Transformer Primary

Primary-side disconnection with optional integral fused overcurrent protection.

Motor Circuits

Load-break disconnection with optional overcurrent protection for motor loads.

Application configuration and overcurrent protection depend on system requirements.

FAQ

What is load interrupter switchgear?

The MES-Series is medium-voltage, air-insulated load interrupter switchgear designed for three-phase load switching, disconnection, and visible isolation.

Can the MES-Series be fused or unfused?

Yes. The MES-Series can be configured without integral overcurrent protection or with optional current-limiting fuses rated from 50A to 1200A.

What voltage and current ratings are available?

The MES-Series is available for 2.4kV through 38kV three-phase systems with 200A, 600A, and 1200A switch ratings. The 1200A switch rating is available up to 15kV.

Can MES switchgear be installed outdoors?

Yes. NEMA 1 construction is available for indoor installations and NEMA 3R construction is available for outdoor installations.

Can the disconnect position be visually confirmed?

Yes. Each load-break switch section includes a Lexan viewing window that provides a clear view of all three switch blades.

Technical Resources

MES Brochure

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Engineering Specification

View Online

APTView SCADA

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Ready to Get Started?

Our team can help review system voltage, switch rating, enclosure requirements, overcurrent protection, and other project-specific configuration needs.

Contact our sales team to discuss your application and determine the right MES-Series configuration for your system.

Request a Quote