Motion Control And Relay Cards; Brake Resistors; Sine-Wave Filters; Du/Dt Filters - Danfoss VLT AQUA Drive FC 202 Design Manual

Options and Accessories Ove...
•
The same cascade controller hardware goes for
the entire power range up to 1.2 MW.
•
Up to 8 pumps in standard cascade set-up. Up to
8 pumps in master/slave set-up.

6.3 Motion Control and Relay Cards

This section describes the motion control and relay card
options that are available with the VLT
202 series. For ordering numbers, refer to
chapter 13.2 Ordering Numbers for Options and Accessories.
6.3.1 VLT ®
Extended Relay Card MCB 113
®
The VLT Extended Relay Card MCB 113 adds inputs/
outputs for increased flexibility.
•
7 digital inputs.
•
2 analog outputs.
•
4 SPDT relays.
•
Meets NAMUR recommendations.
•
Galvanic isolation capability.

6.4 Brake Resistors

In applications where the motor is used as a brake, energy
is generated in the motor and sent back into the drive. If
the energy cannot be transported back to the motor, it
increases the voltage in the drive DC line. In applications
with frequent braking and/or high inertia loads, this
increase can lead to an overvoltage trip in the drive and,
finally, a shutdown. Brake resistors are used to dissipate
the excess energy resulting from the regenerative braking.
The resistor is selected based on its ohmic value, its power
dissipation rate, and its physical size. Danfoss offers a wide
variety of different resistors that are specially designed to
Danfoss drives. For ordering numbers and more
information on how to dimension brake resistors, refer to
®
the VLT Brake Resistor MCE 101 Design Guide.

6.5 Sine-wave Filters

When a drive controls a motor, resonance noise is heard
from the motor. This noise, which is the result of the motor
design, occurs every time an inverter switch in the drive is
activated. The frequency of the resonance noise thus
corresponds to the switching frequency of the drive.
Danfoss supplies a sine-wave filter to dampen the acoustic
motor noise. The filter reduces the ramp-up time of the
voltage, the peak load voltage (U
current (ΔI) to the motor, which means that current and
MG22B222
Design Guide
®
AQUA Drive FC
), and the ripple
PEAK
Danfoss A/S © 01/2018 All rights reserved.
voltage become almost sinusoidal. The acoustic motor
noise is reduced to a minimum.
The ripple current in the sine-wave filter coils also causes
some noise. Solve the problem by integrating the filter in a
cabinet or enclosure.
For ordering numbers and more information on sine-wave
filters, refer to the Output Filters Design Guide.

6.6 dU/dt Filters

Danfoss supplies dU/dt filters which are differential mode,
low-pass filters that reduce motor terminal phase-to-phase
peak voltages and reduce the rise time to a level that
lowers the stress on the insulation at the motor windings.
This is a typical issue with set-ups using short motor
cables.
Compared to sine-wave filters, the dU/dt filters have a cut-
off frequency above the switching frequency.
For ordering numbers and more information on dU/dt
filters, refer to the Output Filters Design Guide.

6.7 Common-mode Filters

High-frequency common-mode cores (HF-CM cores) reduce
electromagnetic interference and eliminate bearing
damage by electrical discharge. They are special nanocrys-
talline magnetic cores that have superior filtering
performance compared to regular ferrite cores. The HF-CM
core acts like a common-mode inductor between phases
and ground.
Installed around the 3 motor phases (U, V, W), the
common mode filters reduce high-frequency common-
mode currents. As a result, high-frequency electromagnetic
interference from the motor cable is reduced.
For ordering numbers refer to the Output Filters Design
Guide.
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