Protected Open-Type Knife Switch

Dongfa Intelligent, a manufacturer of low voltage electrical products in China, supplies the Protected Open-Type Knife Switch HD11F/HS11F Series for manual isolation and power transfer applications. This open-type knife switch uses exposed contacts to form a visible break after opening, allowing the contact separation to be confirmed directly. The series is designed for low voltage distribution cabinets, industrial control cabinets, PV combiner boxes, and other applications requiring manual switching and visible isolation.

Core Advantages

Open-Type Structure and Visible Break

The open-type structure exposes the switching contacts and creates a clearly visible break when the switch is opened. This allows operators to directly confirm the physical separation of the contacts during manual isolation and maintenance operations.

Compared with enclosed switching devices, the open structure provides a direct visual indication of the contact position. The Protected Open-Type Knife Switch can therefore be used where visible isolation is an important requirement. Enclosed circuit breakers or other protection devices can be selected separately when overload and short-circuit protection is required.

Manual Switching for Distribution and Isolation

The HD11F/HS11F Series is intended for manual switching, isolation, and power transfer in low voltage equipment. Typical applications include distribution cabinet main switches, industrial control cabinet switching, and PV combiner box isolation.

In a distribution system, the knife switch can also be combined with a fuse or circuit breaker according to the protection and switching requirements. The knife switch provides manual isolation, while the associated protection device handles the applicable overcurrent protection function.

AC380V and DC220V Making and Breaking Capacity

The making and breaking capacity of this series reaches rated current under AC380V at cosφ = 0.72-0.8 and under DC220V at T = 0.01-0.0115. The available ratings range from 100A to 1000A.

AC and DC applications should be selected according to the actual system voltage type. Although the specified making and breaking capacities reach the corresponding rated current under both conditions, AC380V and DC220V are different electrical operating conditions and should not be mixed during application.

Current Ratings and Operating Force

The series covers five current ratings: 100A, 200A, 400A, 600A, and 1000A. The specified operating force increases with the current rating, so cabinet operating space and the actual manual operating position should be considered during selection.

Mechanical Life and Electrical Life

Mechanical life refers to no-load switching cycles, while electrical life refers to on-load switching cycles. The two values are specified separately because switching under load results in greater contact wear.

For applications involving repeated switching under load, electrical life should be considered during selection. For maintenance isolation and other lower-frequency switching requirements, mechanical life provides a separate reference for the expected operating cycles.

Short-Time Withstand and Dynamic Stability

The series provides defined short-time withstand and dynamic stability current values for different current ratings. The 1S short-time withstand current ranges from 6kA to 30kA, while the dynamic stability current peak ranges from 15kA to 50kA.

These values should be checked against the short-circuit conditions of the installation. For main incoming or bus-tie positions, the required short-time withstand and dynamic stability levels should be confirmed before selecting the corresponding current rating.

Technical Specifications & Selection Guide

Full Technical Parameters

Key Parameters to Confirm

• Conventional Thermal Current: 100A / 200A / 400A / 600A / 1000A
• Poles: 2P / 3P / 4P
• System Voltage Type: AC380V or DC220V
• Short-Time Withstand Current: Select according to system short-circuit capacity
• Operating Force: Confirm the applicable operating force according to the selected current rating and cabinet operating arrangement
• Mounting: HD11F front-board wiring, HS11F front-board wiring; confirm cabinet mounting dimensions

Information Needed for Replacement Projects

For replacement projects, please provide the original knife switch model, mounting dimensions, conventional thermal current, pole configuration, system voltage type, and quantity. The Dongfa Intelligent technical team can review the information before production to help confirm compatibility.

Manufacturing and Quality Control

Dedicated Low Voltage Production and Testing

Dongfa Intelligent (Zhejiang Dongfa Intelligent Electric Technology Co., Ltd.) was founded in 2012 in Yueqing Economic Development Zone, Wenzhou, Zhejiang. The company initially focused on high voltage electrical manufacturing and later expanded to low voltage electrical products, forming high-low voltage collaborative supply capability.

The Protected Open-Type Knife Switch is assembled on dedicated low voltage production lines. Before shipment, each unit undergoes mechanical operation testing, contact testing, and dielectric withstand testing. Operating force is individually tested according to the applicable ≤300N, ≤400N or ≤450N requirement.

Certifications and Export Experience

Dongfa Intelligent is certified to ISO 9001, ISO 14001, and ISO 45001 and supports factory audits. Products have been exported to Southeast Asia and parts of Europe, adapting to different market standards and requirements.

Supply Information

Standard products: 7-15 working days. Custom products: 15-30 working days.

Standard products support a 1-unit trial order. The actual production schedule should be confirmed according to the required model and configuration.

FAQ

What is the difference between an open-type knife switch and an enclosed disconnecter?

An open-type Protected Open-Type Knife Switch uses exposed contacts that form a visible break after opening, allowing the contact position to be confirmed directly. An enclosed disconnecter keeps the contacts inside an enclosure, so the open position is not directly visible. The appropriate type depends on the required installation structure, isolation method, and protection arrangement.

How should short-time withstand current be selected?

The required short-time withstand current should be selected according to the short-circuit capacity of the installation. For main incoming or bus-tie positions, the system fault-current conditions should be checked against the available 6kA, 10kA, 20kA, 25kA, and 30kA levels.

Can the product be used for both AC380V and DC220V applications?

The Protected Open-Type Knife Switch series provides specified making and breaking capacities for both AC380V and DC220V applications. However, the actual system voltage type must be confirmed before selection. AC and DC switching conditions are different, so the two operating conditions should not be mixed.

What current ratings are available?

The HD11F/HS11F Series is available in 100A, 200A, 400A, 600A, and 1000A ratings. The corresponding operating force, mechanical life, electrical life, and short-time withstand values should also be checked when selecting the required model.

What is the difference between mechanical life and electrical life?

Mechanical life refers to no-load switching cycles, while electrical life refers to on-load switching cycles. The electrical life is lower because switching under load produces greater contact wear. For example, the 100A-400A models have a mechanical life of 10000 operations and an electrical life of 1000 operations.

What information is needed for a quotation or replacement?

Please provide the current rating, pole configuration, system voltage type, short-time withstand current requirement, mounting method, and quantity. For replacement projects, the original model and mounting dimensions are also recommended so the configuration can be checked before production.