Unidrive Regen Installation Guide
21
Issue Number: 2
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7.9
Radiated emission
Radio frequency emission in the frequency range from 30MHz to 1GHz is mainly radiated directly from the equipment and from the wiring in its
immediate vicinity. Operation in regenerative mode does not alter the radiated emission behaviour, and the EMC data sheet for the individual
Unidrives used should be consulted for further information.
N
Theoretically the use of two drives physically close together can cause an increase in emission level of 3dB compared with a single drive, although
this is usually not observed in practice. All Unidrives have sufficient margin in respect of the generic standard for the industrial environment EN50081-
2 to allow for this increase.
7.10
Wiring guidelines
The wiring guidelines provided for the individual drives also apply to regenerative operation, except that the switching frequency filter must be
interposed between the input drive and the RFI filter. The same principles apply, the most important aspect being that the input connections to the RFI
filter should be carefully segregated from the power wiring of the drives which carries a relatively high “noise” voltage.
7.11
Multi-drive systems
It is common for regenerative drive systems to be constructed using numbers of drives with a single input stage, or other more complex
arrangements. It is generally not possible to lay down specific EMC requirements for such systems, since they are too large for standardised tests to
be carried out. In many cases the environment corresponds to the “second environment” as described in IEC61800-3, in which case no specific limit
to conducted emission is required. National legislation such as the European Union EMC Directive does not usually require that complex installations
meet specific standards, but only that they meet the essential protection requirements, i.e. not to cause or suffer from electromagnetic interference.
Where the environment is known to include equipment which is sensitive to electromagnetic disturbance, or the low voltage supply network is shared
with domestic dwellings, then precautions should be taken to minimise conducted radio frequency emission by the use of a filter at the system power
input. For current up to 300A the Control Techniques filters listed previously are suitable.
For currents exceeding 300A up to 2400A suitable filters are available from the following manufacturers:
Siemens B84143.A250.S (range up to 2500A)
Schaffner FN3359-300-99 (range up to 2400A)
These filters may not give strict conformity with EN50081-2, but in conjunction with the relevant EMC installation guidelines they will reduce emission
to sufficiently low levels to minimise the risk of disturbance.
NOTE
