SIEMENS
SINAMICS DCM
Accessories and supplementary components
SIMOREG CCP
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Siemens D 23.1 · 2014
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Overview
SIMOREG CCP
The Converter Commutation Protector SIMOREG CCP is used to
protect line-commutated SINAMICS DC MASTER converters in
inverter operation against inverter commutation faults.
For line-commutated inverters, an appropriate line-side counter
voltage is required in order to commutate the current between
the individual power semiconductors. Commutation can be
prevented from being completed (commutation fault) as a result
of uncontrolled switching operations, line supply dips (weak line
supplies, thunderstorms, etc.). As a result, in the regenerative
feedback direction, a high current flows through the line supply
or a cross-current in the converter. This can result in fuses
blowing or under certain circumstances can destroy the semi-
conductors.
The firmware of the SINAMICS DC MASTER identifies if inverter
commutation faults are pending and then issues the command
to turn off the power semiconductors in the converter to the
SIMOREG CCP. SIMOREG CCP then turns off the power semi-
conductors, ensures that the conditions to reduce the current in
the motor are present and absorbs the magnetic energy stored
in the motor as electric energy.
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Benefits
SIMOREG CCP limits the current that flows when inverter
commutation faults occur to a non-hazardous value so that the
thyristors and the associated super-fast fuses are protected.
This eliminates the complex and time consuming replacement
of fuses after inverter commutation faults.
Although inverter commutation faults cannot be prevented, their
effects can be.
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Gear units and the driven machine are protected by shutting
off the current in time before it reaches its possible maximum
value in the case of a fault therefore protecting them against
inadmissibly high torque surges.
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For high rated system currents, up until now, high-speed DC
circuit breakers were used up until now to protect the fuses
against rupture. By using the CCP, protection is now cost-
effectively possible even for lower line currents, whereby
SIMOREG CCP has the following advantages when compared
to high-speed DC circuit breakers even at high current levels:
- Protection also for circulating currents
- Lower system costs
- Lower space requirements
- No additional air reactor to reduce the current rate-of-rise
when a fault occurs
- Lower operating costs, as it requires no maintenance
- High degree of availability
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Design
SIMOREG CCP distinguishes itself as a result of the compact
and space-saving design.
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Function
The line supply voltage, line current as well as the armature
voltage are continually sensed in SINAMICS DC MASTER.
A possible commutation fault (inverter commutation fault –
inverter shoot-through) is detected from these quantities,
which results in the following measures being initiated:
1. The firing pulses are immediately disabled in the
SINAMICS DC MASTER
2. The converter sends a "turn-off command" to SIMOREG CCP
(via the serial interface).
3. SIMOREG CCP turns off the thyristors by connecting the
pre-charged quenching capacitors anti-parallel to all thyristors.
As a consequence, the current commutates from the converter
into SIMOREG CCP. The quenching capacitors are initially
discharged by the currents that they accept and they are then
charged with the reverse polarity. The armature current starts to
decrease as soon as the voltage of the quenching capacitors
has reached the value of the motor EMF. However, the armature
voltage continues to increase. As soon as it has reached the limit
value, resistors are switched in, which absorb the energy fed
back from the motor during the remaining time of the current
reduction phase.
4. A fault message is initiated in the SINAMICS DC MASTER.
5. The SIMOREG CCP re-charges the quenching capacitors with
the reverse polarity so that a new quenching operation is
possible.
Each time that the line supply voltage is switched in
(e.g. via a
line contactor), SIMOREG CCP requires approximately 3 s until
it is ready for use as the quenching capacitors must first be
charged up.
After a quenching operation,
SIMOREG CCP requires a certain
time until it is ready for use again. The duration depends on the
operations during the quenching process and immediately
afterwards. On the one hand, the quenching capacitors in
SIMOREG CCP must be charged to the required value with the
reverse polarity (approx. 10 s). On the other hand, the chopper
resistors, that convert the energy into heat when the armature
current is reduced, require a cooling time calculated using an
algorithm in the firmware. Depending on the amount of energy
that was dissipated, this can take up to approx. 20 min.
SINAMICS DC MASTER has setting and monitoring parameters
for commissioning, operation, monitoring and diagnostics of the
SIMOREG CCP. The state of the SIMOREG CCP is signaled via
connectors and the triggering of the SIMOREG CCP or
erroneous states are signaled using fault and alarm messages.
Data is exchanged between the SINAMICS DC MASTER and
SIMOREG CCP via the serial interface.
© Siemens AG 2014