Nautel NX15, Operation And Maintenance Manual

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NX15/NX25 Operations and Maintenance Manual Description
Issue 6.0 2019-01-31 Page 1-11
Shutback:
Shutbacks can be caused by the following alarms: SWR Shutback (exciter), Fast SWR Shutback
(controller), Over-Current Shutback (exciter), Over-Voltage Shutback (exciter) and Arc
Shutback (controller).
• During a single shutback event (see Figure 1.3 ), the transmitter reduces the output
power to 0 W, and remains in that state for 100 ms. This allows time for an arc or tran-
sient fault to clear. After 100 ms, the output power exponentially ramps up (to the
power set point or the power limit set by the exciter, whichever is lower).
• After 30 s, the transmitter returns to full power under control of the normal ALC.
When a shutback occurs, the cutback accumulator is set to a normalized value of 1.
This value decays at a rate of 1/60 of a second (0.0167 s) so after 60 s, the accumulator
value returns to 0 and the shutback event is no longer in memory.
Figure 1.3: Shutback Event