Input Side Monitoring And Protection; Input Side Monitoring - Siemens SINAMICS PERFECT HARMONY GH180 Function Manual

Operating the Control

7.9 Input Side Monitoring and Protection

7.9 Input Side Monitoring and Protection
7.9.1

Input Side Monitoring

The control monitors input side and output side voltages and currents. Input side monitoring
allows the control to respond to events on the input side of the drive. RMS values of the input
currents and voltages are available, along with input power, kVA, energy and power factor.
Figure Input Side Monitoring shows a simplified view of the functions implemented for input
side monitoring. Quantities such as drive efficiency, average input current THD, and individual
harmonic component in input voltages/currents are also calculated. All variables have an
accuracy of ±1%, except for efficiency, which is < ±2% and input current THD, which is ±1% above
~60% of rated power. Table Symbols used in Figure Input Side Monitoring lists symbols used in
the following figure and describes the parameters they represent. The definitions of I
components of the input current are different from the output side quantities.
Input side monitoring allows the drive to protect the secondary side of the transformer from
abnormal conditions. Excessive drive losses and one cycle protection faults are generated under
such conditions. Input side control also provides torque current limiting for line under-voltage,
single-phasing, and transformer overload conditions.
Note
When output power is less than or equal to 5% rated output, the efficiency calculation causes
errors and so the efficiency is clamped to 90%.
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