APPENDIX A
pg. 141
Return to TOC Curtis 1232E/34E/36E/38E & 1232SE/34SE/36SE/38SE Manual, os 31 – May 2017
APPENDIX A
VEHICLE DESIGN CONSIDERATIONS
REGARDING ELECTROMAGNETIC COMPATIBILITY (EMC)
AND ELECTROSTATIC DISCHARGE (ESD)
DECOMMISSIONING AND RECYCLING THE CONTROLLER
ELECTROMAGNETIC COMPATIBILITY (EMC)
Electromagnetic compatibility (EMC) encompasses two areas: emissions and immunity. Emissions are
radio frequency (RF) energy generated by a product. is energy has the potential to interfere with
communications systems such as radio, television, cellular phones, dispatching, aircra, etc. Immunity
is the ability of a product to operate normally in the presence of RF energy.
EMC is ultimately a system design issue. Part of the EMC performance is designed into or inherent
in each component; another part is designed into or inherent in end product characteristics such as
shielding, wiring, and layout; and, nally, a portion is a function of the interactions between all these
parts. e design techniques presented below can enhance EMC performance in products that use
Curtis motor controllers.
Emissions
Signals with high frequency content can produce signicant emissions if connected to a large enough
radiating area (created by long wires spaced far apart). Contactor drivers and the motor drive
output from Curtis controllers can contribute to RF emissions. Both types of output are pulse width
modulated square waves with fast rise and fall times that are rich in harmonics. (Note: contactor
drivers that are not modulated will not contribute to emissions.) e impact of these switching
waveforms can be minimized by making the wires from the controller to the contactor or motor as
short as possible and by placing the wires near each other (bundle contactor wires with Coil Return;
bundle motor wires separately).
For applications requiring very low emissions, the solution may involve enclosing the controller,
interconnect wires, contactors, and motor together in one shielded box. Emissions can also couple
to battery supply leads and throttle circuit wires outside the box, so ferrite beads near the controller
may also be required on these unshielded wires in some applications. It is best to keep the noisy
signals as far as possible from sensitive wires.
Immunity
Immunity to radiated electric elds can be improved either by reducing overall circuit sensitivity
or by keeping undesired signals away from this circuitry. e controller circuitry itself cannot be
made less sensitive, since it must accurately detect and process low level signals from sensors such
as the throttle potentiometer. us immunity is generally achieved by preventing the external RF
energy from coupling into sensitive circuitry. is RF energy can get into the controller circuitry via
conducted paths and radiated paths.
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