MAGNET POWER SUPPLY SYSTEM 7000
36
DANFYSIK A/S - DK 4040 JYLLINGE - DENMARK.
4.3.11
Soft start
The soft start circuit enables the Power Amplifier to smoothly ramp up the output current. This
circuit has nothing to do with the normal ramp time controller in the regulation circuit, but ensures
only a proper start of the Power Amplifier.
The circuit is build around U911
When the "main power signal" switches on the integrator output ramps slowly up until D903 is
reversed. It takes about 3 seconds to ramp to max output.
Soft Start pulls down the current limit signal via D903. Slowly this voltage increase and finally the
D903 are reversed.
4.3.12
Analog local/remote current set point controls
Shifting between Local and Remote SET value is done in the analog switch U906A.
4.3.13
Slew Rate limit
The slew rate limit is build around U905. The slew rate is adjustable from 5A/sec to 400A/sec
at P902.
Always adjust to minimum slew rate needed for best protection of the system.
4.3.14
Current limit
SET value from U906A is limited via the voltage from the Current Limit trimmer on the back
side of the Front Panel PCB. U908 and U909 are controlling this limitation.
4.3.15
Summed Measured Current
The measured current signal from U301B is converted into a proportional current, U914A and
U920A.
Each Slave unit feeds this current to the parallel interface cable.
The Master unit converts the total current in the parallel cable into a voltage. The number of
units in parallel, U914B, U915B and U919 then scales this voltage. Hereby 100% current out is
equal to ±10V. The scaling is controlled by a 3-bit code coming from the Front Panel.
