Circuit Protection Device

Circuit Protection Device

At Captor Corporation, our strong background in building electronic assemblies for aerospace applications prompted one of our clients to approach us for a replacement circuit protection device. What they had in their possession was an incomplete build package, so they leveraged our engineering expertise to fill in the blanks.

Designed to convert 115 VAC, 3-phase, 400 Hz input to 270 VDC, 6.5 A output, this device incorporated custom internal wire harnesses, AC power line filter, DC power lines, and lightning protection. It featured military grade input and output terminations and was constructed to withstand operating temperatures in the -55°C to +105°C range. Our sourcing engineer was responsible for finding replacement parts for obsolete components, and we manufactured some of the components in-house after procuring a suitable substitution for some obsolete materials.

Built according to IPC-A-610 Class 3 workmanship standards for high-reliability and mission critical applications, this device featured overall dimensions of 12.00″ in length x 8.00″ in width x 5.00″ in height and weighted approximately 7 lbs. We constructed the chassis from dip brazed aluminum to produce leak-tight and EMI shielded joints then applied an aerospace grade coating to provide a tough, resilient finish resistant to chemicals, solvents, and abrasion.

This device required extensive electrical and environmental testing. Various MIL-STD-202 test methods validated criteria such as dielectric withstand voltage (DWV), insulation resistance, capacitance, insertion loss, and point-to-point DCR. Environmental testing determined the effect of vibration, thermal shock, thermal cycling, humidity, and altitude.

Feedback from the client was outstanding. They confirmed that it functioned perfectly as a direct replacement, even with the material substitution. We supplied them with a complete new build package to simplify future sourcing.

If you would like more information about this project or our ability to engineer, build, and assemble custom circuit protection devices, contact us today.

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Circuit Protection Capabilities


This product is a built to a customer print for an Air Force Application. It features 115 VAC to 270 VDC Rectifier, Internal Wire Harnesses, AC Power Line filter, DC power lines, and provides lightning protection.

Operating Voltages and Currents

115 VAC, 3 phase, 400 Hz, 4 amps
270 VDC, 6.5 amps

Electrical Testing Performed

DWV: MIL-STD-202, Method 301
Insulation Resistance: MIL-STD-202, Method 302, Test Condition A
Capacitance: MIL-STD-202, Method 305
Burn-In at rated voltages and currents
Insertion Loss: MIL-STD-220
Point to Point DCR measurements

Environmental Testing Performed

Vibration: MIL-STD-202, Method 204, Test Condition D
Thermal Shock/Cycling: MIL-STD-202 Method 107, Test Condition A
Humidity: MIL-STD-810 Method 507
Altitude: MIL-STD-202, Method 105, Perform DWV and IR

Input Termination


Output Termination


Overall Part Dimensions

12.00 x 8.00 x 5.00 inches

Part Weight

7 pounds

Operating Temperature Range

-55° to +105°C

Non-Operating Temperature Range

-55° to +125°C

Chassis Material

Dip Brazed Aluminum

Chassis Finish

Painted in accordance with MIL-PRF-85285


Angle Bracket Feet

Industry for use

Air Force, Aerospace

Standards met

AS9100 quality system, ANSI/IPC-A-610 Class 3 workmanship, IPC/WHMA-A-620