Overview of the 700 Series Thermal Switch
Specified for use in both unmanned satellites and modern manned/unmanned space vehicles, these switches, qualified to NASA-Goddard Specifications, offer exceptional reliability and temperature stability. Each unit is individually tested and shipped with its own acceptance data sheet.
These high-reliability switches receive an extensive battery of screening tests, assuring customers a product with the highest degree of workmanship and reliability. They meet or exceed the requirements set forth in MIL-PRF-24236/1, Type I, Class 4. Residual gas analysis and Group B testing are performed on every production lot. Upon testing and inspection, Acron Aviation, serializes each switch and completes an individual data sheet containing the acceptance test data.
Thermal switches exported from the United States must be done in accordance with the export administration regulations (EAR) and/or the international traffic in arms regulations (ITAR) as applicable.
Key features
- All welded stainless steel construction
- 1000 cycles of run-in while monitoring contact resistance, 50 milliohms max, missed cycle detection
- Residual Gas Analysis and Group B Testing
- Able to withstand high vibration and shock levels
- Push to Open snap-action contact operation
- Meets or exceeds requirements of S-311-641/03
- Stainless and super Alloy Construction
- Internal cleanliness 100% verified by micro-particle analysis
- Each switch serialized and shipped with individual test data sheet
- Low contact resistance: 25 milliohms maximum
- Hermetically sealed & backfilled with dry Nitrogen & 10% Helium tracer
Typical applications
- Propulsion lines
- Electronics compartment temperature control
- Cold plate temperature monitoring and control
- Optics and instrumentation temperature control
- Surface and strip heater control
- Battery charge rate and heater control
- Rocket motors and thrusters
- Overheat protection
- Electric motor pre-heater control
- Hydraulic/pneumatic actuator freeze protection
- Environmental control system limit indication and control
- System fail-safe
Technical specifications
Performance characteristics
| Contact arrangement | SPST |
| Contact ratings |
|
| Dielectric withstanding volate | 1250 VAC RMS - terminals to case, 500 microamperes maximum leakage |
| Insulation resistance | 500 megohms minimum at 500 VDC - terminals to case |
Environment (MIL-STD-202)
| Vibration (sine) | Method 204, 50g to 2000 Hz, 30g to 2500 Hz |
| Vibration (random) | Method 214, over 30g RMS, 20 to 2000 Hz |
| Ambient temperature range | -183ºF to 400ºF (-201° to +204°C) |
| Moisture resistance | Method 106, 240 hours, 90-98% RH, and from +77°F to +149°F (+25°C to 65°C) |
| Hermetic seal | Method 112, Cond. C, Procedure IV, 1.0 x 10-8 Atm, cc/sec max leak rate |
| Solderability | Method 208 |
| Shock | Method 213, 100g/6ms, 750g/0.5ms |
| Thermal shock | Method 107, Condition B, -120°F to +257°F (-49°C to 125°C) |
| Acceleration | Method 212, Condition A, 30g |
| Salt spray | Method 101, Condition B, 48 hours |
Acceptance test data
| Test | Criteria |
| Contact resistance monitored burn-in | 1,000 cycles min, 50 mΩ max` |
| Random vibration | 22.7g RMS |
| Particle impact noise detection (PIND) | No particle noise |
| Calibration / setpoint | 3 cycles, 1°F min/max |
| Creepage (ARC duration) 3 cycles | <5 msec, 600 VDC, 1°F min/max |
|
Seal: Fine leak Seal: Gross leak |
≤1 x 10-8 Atm. cc/sec No bubbles |
| Contact resistance - 3 cycles | 25 milliohms max (6 VDC, .1A) |
| Weight | Varies by configuration |
| Dielectric withstanding voltage - Terminals to case | 1250 VAC RMS, 60 Hz |
| Insulation Resistance - Terminals to case | 500 megohms min, 500 VDC |
| Inspection of product | Final visual |
Temperature setpoint ranges and tolerances
| Specified temperature setpoint range (°F/°C) | Standard setpoint tolerance (°F/°C) |
| -120 to 0 (-84.4 to -17.8) | ±6 (±3.3) |
| +1 to 250 (–17 to 121) | ±5 (±2.8) |
| 251 to 350 (121.7 to 148.9) | ±7 (±3.9) |
More Thermal Switches
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