2 - Fagor Automation

Connection diagrams
10.
CONNECTION DIAGRAMS
Electrical cabinet. Diagrams
354
DDS
HARDWARE
Ref.1307
334
A stop may be caused by:
opening the main power switch - S1, one or several fuses have
blown or there is simply a power outage while the system is running.
The motor brakes with emergency ramps if they were initially set by parameters.
Regardless of the power supply being used, it will not be possible
to return to mains the excess energy generated by braking
(remember that the mains connection has been opened). It causes a
voltage rise at the power bus as a result of saving that energy at the capacitors.
NOTE. Remember that the energy saved at the capacitors responds
to the formula: Energy saved = 0.5 C·V²
When exceeding a certain bus voltage (760-768 V DC) the Ballast circuit
is activated to dissipate that excess of energy in an resistor (internal
or external) and the motor performs a controlled stop (with motor
torque).
Even when having activated the Ballast circuit, if there is a problem with
it (e.g. poor connection of the external resistor) the bus voltage would
keep rising until reaching its maximum value allowed (790 V DC) and
would issue error E215 for bus over-voltage. It would deactivate the
“Drive Enable” function and the motor would stop by friction without motor
torque.
Opening of power contactor - KM1 because the contact KA1 associated
with the relay - KA1 has opened. The braking operation would be
the same as in the previous case when using a PS-65A or a PS-25B4
power supply. If it is a regenerative power supply (XPS or RPS) it
brakes with emergency ramps if they have been previously set by parameters.
The excess energy generated by braking is returned to mains
just a few seconds before opening contactor - KM1 thanks to the delayed
deactivation of the relay - KA3. If for any reason the power bus
voltage kept rising, the braking operation would be the same as that of
the previous case.
NOTE. Remember that RPS power supplies do not have a Ballast circuit
and if the application requires one, an off-the-shelf circuit will have
to be used.