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Description
3.3 Power unit
External raw water circuit
The raw water flows through the heat exchanger. The heat exchanger cools the deionized water.
If other raw water specifications apply, titanium heat exchanger plates or tube bundle heat
exchangers are available (optional).
NOTICE
Material damage caused by deposits of suspended solids
If you reduce the flow rate to reduce the raw water usage, then deposits of suspended solids
can build up in the heat exchanger as a result of the slow flow rate.
These suspended solids can then cause the cooling system to fail. The drive could be damaged.
Only reduce the raw water flow rate if the raw water does not have any suspended solids.
3.3.2
Principle of operation
3.3.2.1
Fuseless technology
The converter is of fuseless design. In the event of a fault, limiting of the overcurrent at the input
terminals should be ensured by an appropriate transformer design. In addition, the converter
requires matched circuit breakers with a tripping time of 80 ms. The closed-loop control system
triggers the circuit breakers. Each circuit breaker must be equipped with a fail-safe OFF contact
and an undervoltage coil.
Internal current transformers sense the current and evaluate it electronically. The open-loop and
closed-loop control systems prevent an impermissible rise in any overcurrent by switching the
line-side converter to inverter operation.
NOTICE
Fault due to incorrect configuration of line supply and transformer impedances
On the line side, the converter is designed for short-circuit-proof operation. Short-circuit-proof
operation is only guaranteed if the line supply and transformer impedances are in conformance
with the respective specifications in the system-specific data.
If the supply and transformer impedances cannot be maintained, material damage to the
converter can occur.
Observe the system-specific values in the "Technical data and drawings" chapter.
Work during braking operation, the motor-side converter (MSR) as rectifiers and the line-side
converters as inverters. In the event of a fault during braking, the two motor-side converters
immediately switched over to inverter operation. The current in the DC link is suppressed as a
result. After that, the circuit breaker is opened.
The leakage reactances of the line transformer or the machine and the supply line from the
feeding supply system limit overcurrent in the event of internal short-circuits. In this case, the
circuit breaker responds sufficiently quickly to prevent consequential damage.
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3rd Party LCI Control Upgrade
Operating Instructions, 02/2022, A5E31872818
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