Single Phase Motor Energy Control - Page 8 of 20
3.3 HARMONICS
The EnviroStart
Single Phase Motor Energy Control, like all electronic systems, does
produce low-level harmonics during operation. The SDPMEC is however a controlled
systems, switching taking place at or very near to the zero crossover points of the
waveforms therefore significantly reducing radiated and communicated harmonic content.
As the
EnviroStart
units produce negligible harmonic levels during normal running it is
excluded from the constraints of such specifications by definition; however with our policy of
ensuring maximum compliance and minimum environmental pollution our design standards
ensure that we fall well below the limits set.
Typical test values* of harmonic currents on an
EnviroStart
controlled motor operating in Energy Save Mode yielded <14% for 5
th
Harmonic and <4% for 7th harmonic, significantly within the accepted and specified limits.
Maximum limits are unlikely to be exceeded in normal operation even during ramp up and
ramp down periods.
*Taken from test report produced by CTS Ltd of Bromsgrove, Worcestershire 18
th
July 2003
3.4 HEAT LOSSES
For heat calculation purposes it should be assumed that EnviroStart units have a power loss
of 4W/A at full conduction,
3.5 CONTROL PANELS/CABINETS WITH MULTIPLE UNITS
If more than one
EnviroStart
is to be installed in a single enclosure the heat dissipation
figures should be added together before selecting cooling system requirements.
3.6 IMMUNITY FROM INTERFERENCE
EnviroStart
generally has a high level of immunity to externally generated interference and
as a zero volt switching control is a minimal contributor.
3.7 COIL SUPPRESSION
Any coil that is connected to the
EnviroStart
, shares a common control supply or is
mounted in the same enclosure must be suppressed using RC circuits.
3.8 LIGHTNING STRIKES/VERY HIGH VOLTAGE TRANSIENTS
In areas subject to frequent lightning strikes or other high voltage transients, a suitably rated
metal oxide Varistor (MOV) or transient voltage suppressor (TVS) should connect each
input line to earth.
3.9 CONTROL VOLTAGE TRANSIENTS
Where the control supply to the
EnviroStart
is thought to be subject to mains-borne
interference a suitable line filter with transient interference suppression should be fitted
between the control supply and the
EnviroStart
.
