OSW-SW14

Supported Applications

The Omega OSW and SW14 series Rotary Selector Switches are designed for isothermal, low-resistance switching in temperature measuring circuits. These switches facilitate the selection of multiple inputs from thermocouple, RTD (resistance temperature detector), and thermistor circuits to a single display or recording instrument.

The isothermal design minimizes temperature gradients between input and output wiring to avoid generating thermal EMFs that add error to measurements. The low contact resistance allows for the switching of temperature-sensitive resistance transducers such as RTDs and thermistors without adding appreciable measurement error.

Operating Conditions & Performance

The series is engineered to maintain signal integrity through specific electrical characteristics:

• Contact Resistance: Low-resistance switching ensures minimal impact on resistance-based sensors (RTDs, thermistors).
• Isothermal Design: Minimizes thermal EMF generation in thermocouple circuits by reducing temperature gradients between input and output terminals.
• Pole Isolation: Each pole is fully isolated to prevent cross-talk or shorting between independent channels.
• Off Position Configuration: The off position may be configured as an open circuit or a shorted circuit to keep spurious signals from registering on instruments when no channel is selected.

Configuration Options

The OSW-SW14 series offers extensive configuration options across housing sizes, pole counts, position counts, and contact materials. The full documented envelope includes:

• Housing Sizes:
  • OSW Series: 76 mm (3") or 127 mm (5").
  • SW14 Series: ¼ DIN size (96 x 96 mm).
• Poles: Available in two, three, or four-pole versions.
• Positions: Configurable from 2 to 34 positions depending on the series and pole count. The OSW Series supports up to 40 positions for specific configurations (e.g., 127 mm size).
• Contact Materials:
  • Silver-plated contacts (OSW, SW14x models without 'G' suffix).
  • Gold-plated contacts (OSWG, SW14xG models with 'G' suffix) for enhanced conductivity and corrosion resistance.
• Contact Action:
  • Break Before Make ('B').
  • Make Before Break ('M').
• Handle Options: Standard round knob or optional pistol-grip handle (add suffix '-PG' to model number).
• Termination Types:
  • Standard screw termination for OSW series.
  • Jab-in connections for SW142 series.

Housing and Mounting Dimensions

The physical dimensions vary by size class:

• 76 mm (3") OSW Series: Bezel Size 82.55 mm (3 1/4 in); Panel Cutout not specified for this specific row but generally requires mounting hardware.
• 127 mm (5") OSW Series: Bezel Size 133.35 mm (5 1/4 in).
• ¼ DIN SW14 Series: Panel Cutout 92 mm (3 5/8 in) Dia; Face Height 28 mm (1 1/8 in) with round knob or 67 mm (2 5/8 in) with pistol grip.

Key Product Differences

The series is divided into distinct model families based on size, connection type, and contact plating:

• OSW Series (Silver-Plated): Standard rotary switches with silver-plated contacts. Model numbers follow the format OSW[Size]-[Positions]. The 'T' suffix indicates a 3-pole configuration (e.g., OSWT).
• OSWG Series (Gold-Plated): Identical to the OSW series but features gold-plated contacts. Model numbers include a 'G' after the size indicator (e.g., OSWG, OSWGT).
• SW142/SW143/SW144 Series: ¼ DIN switches featuring jab-in connections.
  • SW14x: Silver-plated contacts.
  • SW14xG: Gold-plated contacts (e.g., SW142G, SW143G).
  • The third digit in the model number indicates pole count: '2' for 2-pole, '3' for 3-pole, and '4' for 4-pole.
  • Contact action is indicated by a suffix ('B' or 'M').

Optional pistol grip handles are available as an add-on (suffix '-PG') or via retrofit kits. Pre-configured panels with connectors, switches, and meters installed may be consulted through sales.