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NSI Support Projects

IRMU

IRMU - Initiator Resistance Measurement Unit

The IRMU is a highly accurate 4-wire Ohm Meter used to test the bridge wire in the NASA Standard Initiator (NSI). The NSI is used to initiate the detonation of an explosive bolt, shape charge, etc. The explosives are used for a variety of applications including: separating the solid rocket boosters from the main fuel tank on the shuttle, ejection seats, vehicle launch pad bolts, etc. The IRMU uses a PC interface via a USB port to log data, perform self-diagnostic tests, calibrate the instrument, etc.

Summit Products designed and manufactured the IRMU and coded a custom Windows based program to NASA specifications.

IRMU Cable for NSI-2

IRMU Cable for NSI-2

In a separate contract, Summit Products designed and manufactured a highly reliable cable with a Kelvin connection (4-wire) for the IRMU. The NSI connector incorporates self-aligning sockets that will correct for any angular tolerance of the NSI pins. During life cycle testing, the cable surpassed the insertion / de-insertion requirement over 4 times when the test was finally terminated.

IRMU Cable for NSI-3A

IRMU Cable for NSI-3A

In another contract, Summit Products designed and manufactured an IRMU Cable for use with the NSI-3A. The NSI-3A is a next generation NSI that is capable of withstanding launch vibrations experienced by a capsule, like the Orion, that sits on top of a conventional rocket.

NSI Shorting Plug

NSI Shorting PLug

Summit Products designed and manufactured a shorting plug that is used to prevent ESD from damaging the squib during transportation and installation in the space vehicle. The design provides for a tether cable for blind installations, like capsule escape hatches, etc. It incorporates self-aligning sockets that will correct for any angular tolerance of the NSI pins.

Some of the internal features pushed the tolerance limits of injection molding.