Santerno DCREG2 Series User Manual page 116

15P0059B3
USER MANUAL
As soon as current drops to zero, relay RC energizes, self-maintaining. Then, once current conduction
switches from bridge A to bridge B, current becomes negative.
Bridge B is set to current limit due to the low value set through potentiometer PI and sent to auxiliary
input AnIn 1, which is configured as current limit for bridge B through parameter C120. Its incoming signal
is weakened by parameter P128 to exploit the whole scale of the potentiometer.
Current is kept constant for the time set in parameter P195 (residual magnetization is suppressed); when
the time set in P195 is over, contact of digital output MDO 5 closes (MDO 5 is set as "current limit
attained" by default) and relay RF is energized, self-maintaining.
Contact NC of RF on terminal 24 of ENABLE opens (stand-by command), so current is forced to zero with
the max. positive voltage available applied to the magnet (approx. +470 VDC with 400 VAC).
When voltage and current cancel out, the converter is really disabled; contact MDO 4 opens and turns off
indicator light LMA.
As soon as current drops below the current threshold, relay RI deenergizes, thus allowing to send a new
energizing command.
When button PE is pressed again, self-maintenance is disabled for relays RA, RC, RF, and the operating
cycle can start again.
NOTE: What explained in the section above concerns loads consisting in only one electromagnet (or in a
fixed number of electromagnets) and loads consisting in a variable number of electromagnets, e.g.
multiple parallel-connected electromagnets, some of which can be disabled.
If a variable number of electromagnets is used, you must decrease time by time the value of parameter
C000 down to the sum of rated currents of operated magnets, in order to make sure that the current for
each electromagnet never exceeds both forward value during initial boost operation and reverse value
during final counter-energizing.
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