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ISP - Rev 6/95
4.7 Protective functions
All the protective functions (excluding 4.7.6) activate internal inhibit. There
are two modes of resetting the amplifier after the cause of the inhibit
disappears: Self Restart and Latch.
- Self restart: The amplifier is inhibited only for the period that the inhibit
cause is present.
- Latch: All failures latch the inhibit and only a reset signal will clear the
latch.
4.7.1 Short circuit protection
This protection is realized by sensing current in the DC line. Every current
peak above a certain value will inhibit the amplifier for a period of approx.
30mS (if in restart mode).
The amplifier is protected against shorts between outputs and either output to
ground.
4.7.2 Under/over voltage protection
Whenever the DC bus voltage is under or over the limits indicated in the
technical specifications, the amplifiers will be inhibited.
4.7.3 Temperature protection
Temperature sensor is mounted on the heatsink. If, for any reason, the
temperature exceeds 85§C the amplifier will be inhibited. The amplifier will
restart when the temperature drops below 80 §C.
4.7.4 Insufficient load inductance
Whenever the load inductance is too small, the current spikes will be very
high. In such cases the amplifier will be disabled.
4.7.5 Loss of velocity feedback signal
If the amplifier loses the velocity feedback signal it will inhibit itself. In
the "Self Restart" mode it will restart after a delay of 6-8 seconds.
4.7.6 Shunt regulator duty cycle
Whenever the ratio between "ON" time to "OFF" time of the shunt exceeds 5-10%
the shunt will be inhibited.