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1. Preloading Function – Eliminating Mechanical Gaps

Background:
The insulating rod, typically made from epoxy resin or glass fiber reinforced plastic, connects the operating mechanism to the movable contact of the vacuum interrupter. Over time, due to differences in thermal expansion or prolonged vibration, mechanical joints may loosen, causing deviation in opening and closing positions.

Solution:
One or two disc springs are installed at the rod bolt or connecting pin to apply axial preload (typically 500–2000 N). This preload compensates for manufacturing tolerances and ensures no mechanical clearance between the rod and mechanism, thereby preventing issues such as contact bounce during opening or incomplete closure.

Typical Application:
In mid-mounted circuit breakers (e.g., KYN28 type), disc springs are used at the joint between the insulating rod and the operating mechanism to prevent loosening due to vibrations.

2. Shock Absorption and Impact Protection – Safeguarding Insulating Components

Background:
During the opening operation, the mechanism releases substantial energy, and the insulating rod is subjected to high-impact forces (up to several kN). Brittle materials like epoxy resin are prone to microcracks under such stress.

Solution:
Thanks to their nonlinear elastic characteristics, disc springs can absorb impact energy and reduce peak stress. During the final phase of opening, the compression of the disc spring buffers mechanical shocks, protecting the rod from fracture or degradation of insulation performance.

Typical Design:
A series of disc springs may be used to increase buffering stroke (typically 3–5 mm), matching the overtravel requirements of the breaker during opening.

3. Dynamic Load Compensation – Adapting to Temperature Changes

Background:
Temperature fluctuations can cause mismatched expansion between metal parts and insulating materials, generating additional stress that may compromise structural integrity.

Solution:
The elasticity of disc springs allows for adaptive compensation of minor dimensional changes, reducing thermal stress and maintaining joint integrity. Stainless steel disc springs, with their low thermal expansion coefficient, can sustain stable preload across a temperature range of -30°C to 80°C.

http://www.raleigh-springs.com
Raleigh Spring Technology Co., Ltd.

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