Background:

The NEB current is monitored by the SPE hardware. The current is limited in this hardware to a maximum value of 9.6 Amps. If the NEB current exceeds this value the SPE will take the NEB offline, however this protection will likely never be exercised since the TRACE solar arrays only produce ~ 9.0 Amps . It is likely that some type of hardware failure has occurred if this protection has been exercised.

Key Telemetry:

PSNEBCURR, PSDPUCURR, PSWAXACTCURR, PSINOPHTRCUR, PSDECHTRCURR, PSINSRHTRCUR (reflects bypass heater current which was moved to the NEB)

Recovery Procedure:

The OE should be notified as well as power subsystem representatives.

Examine the NEB currents (see above) to determine which mnemonic showed a rapid increase. Depending on what failed, the mission may or may not be over. If it possible to continue the mission with the failed hardware, do not turn that load back on once the NEB is back on-line.

References:

TRACE C&DH User’s Guide

FPD - Instrument Turn-On