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Micro Switch
MS-1281 Series Mini Micro Switch
High-Precision Sensing by Pran Electronics Pvt. Ltd.
The MS-1281 Series is a professional-grade sub-miniature micro switch designed for high-sensitivity applications. While standard tactile switches are used for manual user input, the MS-1281 is a mechanical sensing switch. It is engineered to detect physical changes—such as a door opening, a cover being removed, or a lever being moved—and convert that into an electrical signal.
Known for its "leaf spring" contact mechanism, this series provides a reliable, long-life solution at a cost-effective price point, making it a primary choice for tamper detection in energy meters and small household appliances.
Key Specifications
| Feature | Details |
|---|---|
| Contact Arrangement | SPDT (Single Pole, Double Throw - NO/NC) |
| Contact Rating | 1A @ 125V AC / 30mA @ 5V DC |
| Operating Force (O.F.) | 40gf + 20gf (Ultra-light actuation) |
| Mechanical Life | 500,000 Cycles |
| Electrical Life | 10,000 Cycles |
| Operating Temp | -40°C to +85°C |
| Terminals | Brass, Silver Plated |
| Contact Material | Phosphor Bronze with Silver Rivets |
Versatile Terminal & Lever Options
The MS-1281 series is highly customizable to fit different PCB mounting styles and mechanical requirements:
- MS-1281-PL: Straight PCB terminals (standard vertical mount).
- MS-1281-BL: Bent self-clinching terminals (stays in place during soldering).
- MS-1281-DL: Right-angle "D" terminals (side-mount).
- MS-1281-SL: Solder terminals (for wire-to-switch connections).
- Lever Variants: Available with a plain plunger, standard hinge lever, or a long lever (P-XL) for lighter actuation over a larger distance.
Why the MS-1281 is a Designer Favorite
- Snap-Action Reliability: The internal leaf spring ensures a "snap-action" response. This means the transition between Normally Open (NO) and Normally Closed (NC) is near-instantaneous, reducing electrical arcing and extending contact life.
- Dual-Function Logic (SPDT): Because it features three terminals (Common, NO, and NC), it can be used for both "Press to Turn ON" and "Press to Turn OFF" logic simultaneously, or to switch between two different circuits.
- Tamper-Proof Design: Its high sensitivity and small footprint make it perfect for mounting behind a plastic casing. If a thief tries to pry open a meter or a security box, the MS-1281 detects even a 1.8mm movement and triggers an alarm.
- Industrial Durability: Constructed with a PBT G30 (glass-filled) case and a POM plunger, it is resilient against chemical exposure and high-frequency mechanical vibration.
Common Applications
- Smart Energy Meters: The "standard" choice for detecting top cover or terminal block removal (Anti-Tamper).
- Small Appliances: Safety interlocks in blenders, microwave door detection, and water level sensing in coffee machines.
- Office Equipment: Paper jam detection in printers and lid-close sensors in scanners.
- Industrial Automation: Limit switching for small robotic arms or conveyor gates.
- Consumer Electronics: Reset buttons and mode selection in white goods.
Operational Characteristics (Standard Model)
- Pre-Travel (P.T.): Max 1.8mm (Distance moved before contacts snap).
- Over-Travel (O.T.): Min 0.6mm (Safe distance the plunger can move after clicking).
- Movement Differential (M.D.): Max 0.5mm (Distance between click and release).
