Microhm Electronics developed the  resistors to offer higher pulse performance when compared to generic off-the-shelf versions.  The joule ratings listed for GTW series are not the highest energy rating we can produce for each version, but do give an indication of the overall capabilities available for different physical sizes and resistance value options.  

In general, Microhm Electronics prefer to work with our customers to meet the necessary energy dissipating requirements.  We then use optimized materials and manufacturing techniques to meet the desired rating.  When determining the pulse rating, we assume the resistance wire will absorb all of the pulse (true for short duration pulses) and then size the resistance wire accordingly to provide for a very comfortable safety margin.  

Part of the calibration process for wire wound resistors removes some material from the winding to bring the part within tolerance.  This material removal has the potential to create hot-spots in pulse applications, and is consequently not ideal.  Therefore, we recommend sticking with a 5% tolerance for pulse applications as we can easily wind a part to that tolerance and thus avoid material removal.  If necessary, we can supply parts with a tolerance as tight as 2% without mechanical calibration.


Besides GTW series, NUAL series and VEW series bear excellent pulse handling ability. Common applications include: defibrillators, capacitor charge/discharge circuits, surge current protection, snubbers, power factor control, and lightning strike suppression.