Input Side Monitoring And Protection - Siemens 6SR41 series Product User Manual

Application and Operation

6.13 Input Side Monitoring and Protection

6.13 Input Side Monitoring and Protection
The NXG Control monitors input side voltages and currents, as well as those on the output
side. This allows the control to monitor and 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 " Block Diagram of Input -Side M onitoring" shows a
simplified view of the functions implemented for input side monitoring. Other 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 (< ±2%) and input current THD (±1% above ~60% of rated power). A list of
symbols used in Figure " Block Diagram of Input -Side Monitoring" and a description of the
parameters they represent are given in Table " List of Symbols Used in Figure "Block
Diagram of Input-Side Monitoring". Note that the definitions of Id and Iq 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. Two faults, excessive drive losses, and one-cycle protection are
generated under such conditions. Input side control also provides torque current limiting for
line under-voltage, single-phasing, and transformer overload conditions.
Figure 6-11 Block Diagram of Input-Side Monitoring
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Operating Instructions, Version AE 12/2009, A5E01454341C
Product User Manual