15-08-2014, 10:29 AM
Arcol have special "low inductance" variants of their Al resistors - you just add an "N" before the part number, e.g. NHS50xxxx etc. and their vitreous enamel (the "V" series) resistors.
http://www.arcolresistors.com/wp-content...-05.45.pdf
http://www.arcolresistors.com/wp-content...-13.06.pdf
These resistors do actually use Ayrton-Perry windings.
The reason that the maximum ohmic value is 25% of the normal range is that with, say, a 10R resistor, they divide it in 2, wind in the Ayrton-Perry style, then connect the two windings in parallel, hence 1/4 of the original value. Note also that the maximum voltage is derated by a factor of root 2 (i.e. 1.414).
Arcol claim that this results in the NHSxxx components having 12% (one eighth) of the inductance of the equivalent HSxxx value.
My own 200W dummy load uses 2 x 15R BDS100 in parallel in series with 2 x 1R RCH25 in parallel to make exactly 8 ohms non-inductive all clamped to a LARGE heatsink. This was expensive but a client paid for it :-)
http://www.arcolresistors.com/wp-content...-05.45.pdf
http://www.arcolresistors.com/wp-content...-13.06.pdf
These resistors do actually use Ayrton-Perry windings.
The reason that the maximum ohmic value is 25% of the normal range is that with, say, a 10R resistor, they divide it in 2, wind in the Ayrton-Perry style, then connect the two windings in parallel, hence 1/4 of the original value. Note also that the maximum voltage is derated by a factor of root 2 (i.e. 1.414).
Arcol claim that this results in the NHSxxx components having 12% (one eighth) of the inductance of the equivalent HSxxx value.
My own 200W dummy load uses 2 x 15R BDS100 in parallel in series with 2 x 1R RCH25 in parallel to make exactly 8 ohms non-inductive all clamped to a LARGE heatsink. This was expensive but a client paid for it :-)
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