MarelliMotori MARK XX Manual Del Usuario página 14

5. BOARD LAYOUT
5.1. TERMINALS
U
Power supply
0
S Generator voltage
0 sensing
+ Output (to the exciter
- field)
60
60Hz mode selection
Hz
P Connection to external
Q control device
Connection to ground
of internal EMI filter
5.2. POTENTIOMETERS
VOLT Setup of generator voltage.
Normally the internal potentiometer VOLT permits to adjust the voltage in a wide range; to obtain a
finer possibility of voltage setting or to adjust the voltage from the control panel, or in order to limit the
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voltage range, an external potentiometer can be connected to the terminals P and Q (resistance about
100 kΩ, 1 W, for a voltage regulation of ±5%).
Turn clockwise to increase voltage
U/F Setup of the Corner Frequency.
It is usually set at the factory in order to reduce the excitation when speed becomes lower than 90% of
rated speed at 50 Hz (frequency lower than 45 Hz, or corner frequency). By removing the bridge which
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normally shorts the terminals Hz and 60, the speed protection operates properly for 60 Hz operation
mode.
Turn clockwise to decrease the operation frequency threshold
STAB Setup of regulation stability.
The regulation can be set on the field to adapt it to the characteristics of the plant and the driving
engine (diesel engine, water turbine, gas turbine) in order to obtain the best voltage response. To
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change the stability characteristics of the regulator, the potentiometer STAB must be adjusted.
Turn clockwise to increase the response stability