Emission; Supply Voltage Notching; Supply Harmonics; Switching Frequency Emission - Emerson SP1201 Installation Manual

Safety Product
Introduction
Information information
6.5.3 Compliance with EN61800-3 (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 80. An external EMC filter will always be
required.
This is a product of the restricted distribution class according
to IEC61800-3
In a domestic environment this product may cause radio
interference in which case the user may be required to take
CAUTION
adequate measures.
Operation in the second environment
In all cases a shielded motor cable must be used, and an EMC filter is
required for all Unidrive SPs with a rated input current of less than 100A.
Size 1
Where a filter is required, follow the guidelines in section 6.5.2 General
requirements for EMC on page 79.
For cable lengths up to 10m compliance can be maintained by fitting a
ferrite ring, part no. 4200-0000, 4200-0001 or 4200-3608, to the drive
output. Feed the motor cables (U,V,W) through the ring once.
Size 2 and 3
Where a filter is required, follow the guidelines in section 6.5.2 General
requirements for EMC on page 79.
The second environment typically includes an industrial low-
voltage power supply network which does not supply
buildings used for domestic purposes. Operating the drive in
this environment without an external EMC filter may cause
CAUTION 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.
Refer to section 6.4 EMC (Electromagnetic compatibility) on page 77 for
further information on compliance with EMC standards and definitions of
environments.
Detailed instructions and EMC information are given in the Unidrive SP
EMC Data Sheet which is 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 current Unidrive SP User Guide.
6.5.5 Immunity
The immunity of the individual drive modules is not affected by operation
in the regenerative mode. 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 synchronised to the
supply, there is a limit to the permitted rate of change of supply
frequency. If rates of change exceeding 100Hz/s are expected then C.T.
Technical Support should be consulted. This would only arise under
exceptional circumstances e.g. where the power system is supplied from
an individual generator.
80
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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 30MHz where emission is
predominantly by conduction
• High frequency emission above 30MHz where emission is
predominantly by radiation
6.5.7 Dedicated supplies
The nature of the mains supply has an important effect on the EMC
arrangements. For a dedicated supply, i.e. one which has no other
electrical equipment fed from the secondary of its distribution
transformer, normally neither an EMC filter or a switching frequency filter
are required. Refer to section 4.3.1 Omitting the switching frequency
filter on page 40.
6.5.8 Other supplies
Wherever other equipment shares the same low voltage supply, i.e.
400Vac, careful consideration must be given to the likely need for both
switching frequency and EMC filters, as explained in section
6.5.11 Switching frequency emission and section 6.5.12 Conducted RF
emission .
6.5.9

Supply voltage notching

Because of the use of input inductors and an active rectifier the drive
causes no notching - but see section 6.5.11 Switching frequency
emission for advice on switching frequency emission.
6.5.10

Supply harmonics

When operated from a balanced sinusoidal three-phase supply, the
regenerative Unidrive SP 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.
6.5.11

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 3kHz switching frequency and 50Hz
supply frequency there is current at 2.90, 3.10, 5.95, 6.05kHz 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; Supply assessment on page 40
gives guidelines to help in assessing whether a switching-frequency filter
is required. In case of doubt, unless the drive operates from a dedicated
supply not shared with other loads, it is strongly recommended that the
filter be fitted.
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.
CAUTION
Unidrive SP Regen Installation Guide
Technical Component
Diagnostics
data sizing
Issue Number: 2