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Nasa Standard Initiator (NSI)

Electrical Input, Pyrotechnic Output

Space Electric Initiators

Electric Initiators are commonly used on missiles, launch vehicles, spacecraft, and other aerospace and defense platforms for the initiation of solid rocket motors and other propulsive elements, and actuation of mechanisms such as separation devices, cutters, pin pullers, or isolation values. The Initiator takes an electrical input and provides work in the form of pyrotechnic output.

EBAD manufactures a NASA Standard Initiator (NSI), and a NSI equivalent, the S76-191. The NASA Standard Initiator (NSI) is built to NASA’s drawing SEB 26100001 and is an industry standard initiator, qualified for the extreme environments of space. The NSI has a wide operational range and high level of demonstrated reliability that make it ideally suited for aerospace platforms.

EBAD’s NSI equivalent initiator (S76-191) is an economical alternative single bridge, 1A / 1W no-fire initiator that has similar mechanical, electrical, and pyrotechnic characteristics to the NSI.

Principle of Operation

The NSI and the S76-191 initiator are 2-pin, single bridgewire, electrically activated initiators. Upon application of electrical current, heat is generated and transferred from an internal filament or bridgewire to the surrounding pyrotechnic material, causing powder ignition and a rapid output of heat and gas pressure. The flame and hot particle output from these initiators can be used to ignite downstream pyrotechnics or propellants contained in Cartridge Actuated Devices (CADs) or Propellant Actuated Devices (PADs) such as cutters, pin pullers, separation devices, and isolation valves. Initiation will reliably occur when a minimum “All-Fire” current is delivered to the bridgewire. Similarly, the device will not be initiated when current is maintained below the designated “No-Fire” requirement.

Construction

These initiators feature an Inconel body that houses all the critical elements of the initiator. Both bodies have an internal glass-to-metal seal that allows for physical isolation of the input electrical connections from the output pyrotechnic event. The header design and construction allows for high pressure sealing capability during and after the pyrotechnic event. These initiators have elements that electrically isolate the bridgewire from the body and protect against ESD and other stray electrical energy between the pins and the header. The time-pressure and caloric output is generated from a Zirconium potassium perchlorate output charge. The entire assembly is hermetically sealed.

Applications

The NSI and the S76-191 initiator are suitable for direct initiation of CAD / PAD elements or the initiation of detonation devices when used in conjunction with an EBAD Detonation Booster Assembly (DBA). The wide range of operational temperatures for the NSI and S76-191 initiator make them ideal for use in satellites, spacecraft, and launch vehicles. The initiators are used in the actuation of point separation and release mechanisms, solid rocket motor ignition, gas generators, and CAD/PAD devices.

Key Features

    • Wide operating temperature range
    • Inconel body provides high level of back pressure sealing
    • Hermetically sealed
    • Proven reliability
    • Space rated materials
    • Standard electrical/mechanical interface