What is the selection guide for knife switches?
Release time： 2025-09-30
Selecting a knife switch requires careful consideration of multiple factors. Here's a detailed selection guide:
1. Clearly define the purpose and load
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Uses Determine the application scenarios for knife switches, such as isolating power sources, controlling lighting, or operating electric motors, among others.
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Load characteristics : Select the appropriate knife switch based on the load type (e.g., resistive load, motor load, etc.). For instance, when controlling a motor, you must account for the motor’s inrush current.
II. Rated Current and Rated Voltage
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Rated Voltage : The rated voltage of a knife switch should be no lower than the highest voltage actually used in the circuit.
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Rated current ：
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For general loads, the rated current of the knife switch should be equal to or slightly higher than the load's rated current.
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For motor loads, since the inrush current is relatively high, it is common practice to select a rated current for the knife switch that is approximately three times the motor's rated current.
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3. Structural Form
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Arc-extinguishing device : If the knife switch needs to interrupt a load, it should be a model equipped with an arc-extinguishing shield; however, if it’s used solely for isolating the power supply, a model without an arc-extinguishing shield can be selected.
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How to operate : Select the operating method based on actual operational needs, such as front-side operation, side operation, direct operation, lever-driven mechanisms, and more.
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Installation method : Confirm whether it should be installed vertically or horizontally, and select the corresponding accessory.
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