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Unidrive M Regen Design Guide 131
Issue Number: 4
6.5.3 Compliance with EN 61800-3:2004+A1:2012 (standard for Power Drive Systems)
Meeting the requirements of this standard depends on the environment
that the drive is intended to operate in as follows:
Operation in the first environment
Observe the guidelines given in section 6.5.4 Compliance with generic
emission standards on page 131. An external EMC filter will always be
required.
Operation in the second environment
In all cases a shielded motor cable must be used, and an EMC filter is
required for all drives with a rated input current of less than 100 A.
For longer cables, an external filter is required. Where a filter is required,
follow the guidelines in section 6.5.4 Compliance with generic emission
standards on page 131.
Where a filter is not required, follow the guidelines given in section 6.5.2
General requirements for EMC on page 130.
Refer to the Regen configuration EMC data sheet for further information
on compliance with EMC standards and definitions of environments.
Unidrive M EMC Data Sheets are available from the supplier of the drive.
6.5.4 Compliance with generic emission standards
Use the recommended filter and shielded motor cable. Observe the
layout rules given in the relevant Unidrive M Power Installation Guide.
6.5.5 Immunity
The immunity of the individual drive modules is not affected by operation
in the regenerative mode, refer to Table 10-42 Immunity compliance on
page 303. See drive EMC data sheets for further information.
This guide recommends the use of varistors between the incoming AC
supply lines. These are strongly recommended to protect the drive from
surges caused by lightning activity and/or mains supply switching
operations.
Since the regenerative input stage must remain synchronized to the
supply, there is a limit to the permitted rate of change of supply
frequency. If rates of change exceeding 100 Hz/s are expected then the
supplier of the drive should be consulted. This would only arise under
exceptional circumstances e.g. where the power system is supplied from
an individual generator.
The behaviour of the drive during dips and supply disturbances can be
modified by changing the following drive parameters:
• Regen Synchronization Mode (03.004). Auto-synchronize
(03.004 = 3) allows the drive to continue operating during
symmetrical (balanced) and asymmetrical (unbalanced) supply
faults of up to 2 seconds duration.
• Island Detection Enable (03.030)
• Regen Supply Loss AC Level (03.023)
• Regen Minimum Frequency (03.024) / Regen Maximum Frequency
(03.025). Supply frequency monitoring.
• Regen Minimum Voltage (03.026) / Regen Maximum Voltage
(03.027). Supply voltage monitoring.
Refer to the individual parameter descriptions for more information.
6.5.6 Emission
Emission occurs over a wide range of frequencies. The effects are
divided into three main categories:
• Low frequency effects, such as supply harmonics and notching
• High frequency emission below 30 MHz where emission is
predominantly by conduction
• High frequency emission above 30 MHz where emission is
predominantly by radiation
When running at constant load the drive does not generate voltage
fluctuations or flicker except if island detection / protection is enabled,
since it injects reactive current into the supply. The injection current does
not change with the Regen unit load. Care must be taken to ensure that
the application does not cause the load to vary rapidly, resulting in
flicker.
6.5.7 Other supplies
Wherever other equipment shares the same low voltage supply,
i.e. 400 Vac, careful consideration must be given to the likely need for
both switching frequency and EMC filters, as explained in section 6.5.10
Switching frequency emission and section 6.5.11 Conducted and
radiated RF emission.
6.5.8 Supply voltage notching
Because of the use of input inductors and an active rectifier the drive
causes no notching - but see section 6.5.10 Switching frequency
emission for advice on switching frequency emission.
6.5.9 Supply harmonics
When operated from a balanced sinusoidal three-phase supply, the
regenerative Unidrive M generates minimal harmonic current.
Imbalance between phase voltages will cause the drive to generate
some harmonic current. Existing voltage harmonics on the power
system will cause some harmonic current to flow from the supply into the
drive.
Note that this latter effect is not an emission, but it may be difficult to
distinguish between incoming and outgoing harmonic current in a site
measurement unless accurate phase angle data is available for the
harmonics. No general rule can be given for these effects, but the
generated harmonic current levels will always be small compared with
those caused by a conventional drive with rectifier input.
6.5.10 Switching frequency emission
The Regen drive uses a PWM technique to generate a sinusoidal input
voltage phase-locked to the mains supply. The input current therefore
contains no harmonics of the supply unless the supply itself contains
harmonics or is unbalanced. It does however contain current at the
switching frequency and its harmonics, modulated by the supply
frequency. For example, with a 3 kHz switching frequency and 50 Hz
supply frequency there is current at 2.90, 3.10, 5.95, 6.05 kHz etc. The
switching frequency is not related to that of the supply, so the emission
will not be a true harmonic - it is sometimes referred to as an
“interharmonic”. The possible effect of this current is similar to that of a
high-order harmonic, and it spreads through the power system in a
manner depending on the associated impedances. The internal
impedance of the Regen drive is dominated by the series inductors at
the input. The voltage produced at switching frequency at the supply
point is therefore determined by the potential divider action of the series
inductors and the supply impedance.
This is a product of the restricted distribution class according
to IEC61800-3
In a residential environment this product may cause radio
interference in which case the user may be required to take
adequate measures.
The second environment typically includes an industrial low-
voltage power supply network which does not supply
buildings used for residential purposes. Operating the drive in
this environment without an external EMC filter may cause
interference to nearby electronic equipment whose sensitivity
has not been appreciated. The user must take remedial
measures if this situation arises. If the consequences of
unexpected disturbances are severe, it is recommended that
the guidelines in section 6.5.4 Compliance with generic
emission standards be adhered to.
Failure to fit a switching frequency filter may result in damage
to other equipment, e.g. fluorescent light fittings, power factor
correction capacitors and EMC filters.
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