Discharging capacitors...
Posted by
PROTOBYTE INC.
on 2003-12-27 10:35:15 UTC
No need to add dissipation to an operating system. Simply specify
your mains power switch with another set of poles. Run a pair of
conductors from the output capacitor back to this switch. Include a
series resistor to limit the surge. The TO-220 or Aluminum housed
resistors are easily chassis mounted. When switching power-off the
charge is bled and prevents residual build-up. When specifying the
resistor no need to derate for "one-shot" surge. Depending on style
they'll handle 100-200% rated wattage for 1-10 seconds, due to their
sluggish thermal time constant. An option to the fixed resistor, in
this "switched" scheme, is the "inrush-limiter". These are available
through Digikey and the manufacturer can be found at:
http://www.thermometrics.com
As for "hazards"... good practice suggest you are always aware of the
path current is taking. Placing two fingers across a charged
capacitor could change your ring size for a few days. But, unless
your working barefoot on concrete, the current path remains through
your fingers. The hazard (as I'm sure most here know), is allowing
current to flow across your chest. It only takes a few milliamps to
alter the rhythm of your heart, which could prove lethal. Hence the
safety measure of using "one-hand" in your pocket when the workpiece
is live.
Regards,
Steve
your mains power switch with another set of poles. Run a pair of
conductors from the output capacitor back to this switch. Include a
series resistor to limit the surge. The TO-220 or Aluminum housed
resistors are easily chassis mounted. When switching power-off the
charge is bled and prevents residual build-up. When specifying the
resistor no need to derate for "one-shot" surge. Depending on style
they'll handle 100-200% rated wattage for 1-10 seconds, due to their
sluggish thermal time constant. An option to the fixed resistor, in
this "switched" scheme, is the "inrush-limiter". These are available
through Digikey and the manufacturer can be found at:
http://www.thermometrics.com
As for "hazards"... good practice suggest you are always aware of the
path current is taking. Placing two fingers across a charged
capacitor could change your ring size for a few days. But, unless
your working barefoot on concrete, the current path remains through
your fingers. The hazard (as I'm sure most here know), is allowing
current to flow across your chest. It only takes a few milliamps to
alter the rhythm of your heart, which could prove lethal. Hence the
safety measure of using "one-hand" in your pocket when the workpiece
is live.
Regards,
Steve