Page 351 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

power distribution system that is more than 10 times the drive kVA rating without adding impedance (line reactor
or transformer) in front of the drive. ATTENTION: Only qualified personnel familiar with adjustable frequency AC
drives and associated machinery should plan or implement the installation, start-up and subsequent maintenance
of the system. Failure to comply may result in personal injury and/or equipment damage. ATTENTION: To avoid
an electric shock hazard, verify that the voltage on the bus capacitors has discharged before performing any work
on the drive. Measure the DC bus voltage at the +DC and –DC terminals of the Power Terminal Block. Refer to
the product-specific documentation for location. The voltage must be zero.
• AC fed ungrounded
• B phase ground
• Impedance grounded

• Regenerative unit such as common DC bus supply & brake
• High resistive ground
• DC fed from an active converter *PN-73136* PN-73136 Publication DRIVES-IN003A-EN-P - April 2010
Copyright © 2010 Rockwell Automation, Inc.

Measure Line-To-Line Voltages Verify that the drive input voltage has an unbalance that is less that 3%. Ground
The Drive Ensure that drive grounding is properly connected as illustrated below. The ground wire return between
the motor and the drive must be terminated directly to the drive PE terminal. Shielded cable is recommended
but not always needed. Refer to the product-specific documentation for requirements. Protect The Drive Ensure
that the proper sized input fuses or circuit breakers are installed prior to applying power to the drive. Verify Your
Installation Ensure that all input and output power wiring is correctly wired and securely fastened prior to applying
power to the drive. Unbalanced Percent = (Vmax - Vmin) x 100 (Vavg) Vavg = (VAB + VBC + VCA) 3 Where:
Vmax = maximum line-to-line RMS voltage Vmin = minimum line-to-line RMS voltage Where: VAB, VBC, VCA =
line-to-line voltage
Protect The Drive Ensure that the proper sized input fuses or circuit breakers are installed prior to applying power
to the drive. Verify Your Installation Ensure that all input and output power wiring is correctly wired and securely
fastened prior to applying power to the drive.

Siemens Micromaster 440 (MM440) Series

The MICROMASTER 440 are frequency inverters for speed and torque control of three-phase motors. The various
models available cover the performance range from 120 W to 200 kW (for constant torque (CT), alternatively up to
250kW (for variable torque (VT)). The inverters are microprocessor-controlled and use state-of-the-art Insulated
Gate BipoIar Transistor (IGBT) technology. This makes them reliable and versatile. A special pulse-width modulation
method with selectable Pulse frequency permits quiet motor operation. Comprehensive protective functions
provide excellent inverter and motor protection. With the factory default settings, the MICROMASTER 440 is
suitable for many variable speed applications. Using the functionally grouped parameters, the MICROMASTER
440 can adapted to more demanding applications. The MICROMASTER 440 can be used in both ‘stand-alone’
applications as well as being integrated into ‘Automation Systems’.

Variable Frequency Drive

Speed control, since the result is an adjustment of motor speed.
There are many reasons why we may want to adjust this motor speed.
For example, to A variable frequency drive (VFD) is a type of motor controller that drives an electric motor by
varying the frequency and voltage of its power supply. The VFD also has the capacity to control ramp-up and
ramp-down of the motor during start or stop, respectively.
Even though the drive controls the frequency and voltage of power supplied to the motor, we often refer to this as
Save energy and improve system efficiency
Convert power in hybridization applications
Match the speed of the drive to the process requirements

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CITS : E & H - Electronics Mechanic - Lesson 223 - 236