Automationdirect.com Stellar SR44, User Manual

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4.7.5 – Emissions - Conducted
Conducted emissions are able to travel great distances and may cause interference to any
neighboring consumers connected to the common low-voltage supply network.
Allowable levels for conducted emissions generated by semiconductor motor controllers and
starters are influenced by the nature of the low-voltage power distribution network. The
determining factor is whether the source of power is, either:
(a) a private supply with a single consumer whose Point of Common Coupling (PCC) is at a high or
medium voltage transformer, or
(b) a public low-voltage network with more than one consumer, where the individual PCC is made
directly to the network itself.
The first type of supply (a) is identified as "Industrial", and requires the use of soft starters
compliant with EN 60947-4-2 Table 14: 'Equipment Class A Emission Levels'.
The second type of supply (b) is identified as "Residential" and requires the use of Equipment Class
B Apparatus.
SR44 Soft Starters are able to comply with either classification provided the appropriate action is
taken. (Section 4.7.7 describes the strategies for attaining and maintaining compliance.)
4.7.6 – Important Systems Information:
The specification limits for both equipment classes assume systems are grounded at the star (wye)
point of the supply transformer through low impedance connections.
Certain industries, particularly continuous process industries, employ distribution systems that
operate either with a ground connection through a high impedance or without a ground at all.
These systems may cause severe problems of operator safety when installed with capacitive high
frequency filters. Such systems are not considered in this document.
In the case of an isolated or high impedance grounded system, seek advice from your supplier
before fitting a capacitive high frequency filter to an SR44 Soft Starter. It is essential that the
specifying authority, user, or installer has a clear knowledge of the type of network to which the
product is to be installed before making decisions as to which EMC strategy to adopt.
As supplied, all SR44 products comply with the conducted emissions requirements for Equipment
class A soft starters as defined by EN 60947-4-2:1996 Table 14. However, the length and type of
cable connecting the motor to the starter module materially affects the level of emissions
generated, and can amplify them greatly. The standard also allows different levels of emissions
depending on motor rated current, which also affects the need to fit filters. The EN 60947-4-
2:1996 standard only requires consideration of steady-state conditions for EMC purposes, and
expressly excludes varying conditions such as those during ramp-up and ramp-down. Therefore,
closing a bypass contactor around the module during the run condition will remove the need for
any high frequency filters. However, some of the features (protection, optimizing etc.), which are
active during the run state, are disabled when the bypass contactor is closed. Users need to assess
the cost and merit of fitting a bypass contactor compared with the cost of a filter when it is
required.
Finally, statistics show that the number of disturbances arising from soft starters, operating in a very
wide variety of applications and networks throughout the world, is insignificant. Where EMC
disturbances occur, it is very unlikely that they can be genuinely attributed to a soft starter.
Chapter 4: Electromagnetic Compatibility
SR44 Series Soft Starter User Manual
1st Ed, Rev B 07/31/2019