Nidec POWERDRIVE FX 100T, Руководство по установке

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GENERAL EMC - HARMONICS - MAINS INTERFERENCE
POWERDRIVE FX Installation guide
4729 en - 2017.08 / c
4 - GENERAL EMC - HARMONICS -
MAINS INTERFERENCE
The power structure of frequency inverters leads to the
occurrence of two types of phenomena:
- Low-frequency harmonics fed back to the mains supply,
- Emission of radio-frequency signals (RFI).
These are independent phenomena. They have different
consequences on the electrical environment.
4.1 - Low-frequency harmonics
The rectifier, at the head of the frequency inverter, generates
a non-sinusoidal AC line current.
Courant de ligne consommé par un redresseur triphasé
This current carries harmonics with number 6n ± 1.
The POWERDRIVE FX THDI level is less than 32%:
significantly less than the maximum level defined by standard
IEC 61000-3-12 (< 45%).
4.2 - Radio-frequency interference:
Immunity
4.2.1 - General
The immunity level of a device is defined by its ability to operate
in an environment which is polluted by external elements or
by its electrical connections.
4.2.2 - Standards
Each device must undergo a series of standard tests
(European standards) and meet a minimum requirement in
order to be declared as compliant with the variable speed
drive standards (EN 61800-3).
4.2.3 - Recommendations
An installation consisting exclusively of devices which
comply with the standards concerning immunity is very
unlikely to be subject to a risk of interference.
4.3 - Radio-frequency interference:
Emission
4.3.1 - General
Frequency inverters use high-speed switches (transistors,
semi-conductors) which switch high voltages (around 550 V)
and currents at high frequencies (several kHz). This provides
better efficiency and a low level of motor noise.
As a result, they generate radio-frequency (R.F.) signals which
may disturb operation of other equipment or distort
measurements taken by sensors:
- Due to high-frequency leakage currents which escape to
earth via the stray capacity of the drive/motor cable and that
of the motor via the metal structures which support the motor;
- By conduction or feedback of R.F. signals on the power supply
cable: conducted emissions ;
- By direct radiation near to the mains supply power cable or
the drive/motor cable: radiated emissions .
These phenomena are of direct interest to the user.
The frequency range concerned (radio frequency) does not
affect the energy supply company.
4.3.2 - Standards
The maximum emission level is set by the standards for
variable speed drives (EN 61800-3).
4.3.3 - Recommendations
• Experience shows that the levels set by the standards do
not necessarily need to be observed to eliminate interference
phenomena.
• Following the basic precautions described in section 4.5
generally results in the correct operation of the installation.
4.4 - Mains supply power
4.4.1 - General
Each industrial power supply has its own intrinsic characteristics
(short-circuit capability, voltage value and fluctuation, phase
imbalance, etc) and supplies equipment some of which can
distort its voltage either permanently or temporarily (notches,
voltage dips, overvoltage, etc). The quality of the mains supply
has an impact on the performance and reliability of electronic
equipment, especially variable speed drives.
The POWERDRIVE FX is designed to operate with mains
supplies typical of industrial sites throughout the world.
However, fo each installation, it is important to know the
characteristics of the mains supply in order to carry out
corrective measures in the event of abnormal conditions.
4.4.2 - Mains transient overvoltages
There are numerous sources of overvoltages on an electrical
installation:
• Connection/disconnection of banks of power factor correction
capacitors,
• High-power thyristor-controlled equipment (oven, DC drive,
etc),
• Overhead power supply.
4.4.2.1 - Connection/disconnection of a bank of cos
j
correction capacitors
Connecting power factor correction capacitors in parallel on
the drive power supply line when the drive is running can
generate transient overvoltages that are likely to trip the drive
safety devices, or even damage it in extreme cases.
If banks of power factor correction capacitors are used on the
power supply line, make sure that:
• The threshold between steps is low enough to avoid
causing overvoltage on the line,
• The capacitors are not permanently connected.