Bleeder resistor

A bleeder resistor is built from high voltages controlled. Are used for this high-impedance ( 100 k - 1 M ) resistors that are switched as required in series or in parallel to the voltage source. Due to the high resistance of a sudden power surge is avoided and the available energy reduces slowly.

Parallel connection

The Bleeder (English = bleed bleed called bleeder resistor ) is essential in electrical capacitors as power capacitors suppression capacitors or line filters. It serves to discharge the capacitor after the switching off or is not used within a certain time to safe voltages.

Bleederwiderstände are dimensioned so that they do not impair the function of the capacitors, but after shutting down the device (and possibly opening the case ) ensure that they discharge usually within 5 minutes or less on a voltage < 50 volts.

They are a security measure to prevent an electric shock in case of repairs. They also prevent the recharge of the discharged capacitors due to their dielectric may persist charges. Hiking these charges to the electrodes, capacitors may otherwise accept dangerous voltages again after discharge.

Bleederwiderstände can be incorporated directly into the capacitors or located in the junction box or at the terminals. Capacitors with built Bleederwiderständen are usually indicated on the housing with a resistor symbol. Bleederwiderstände must have sufficient voltage stability and power loss in order not to fail in continuous operation.

Power capacitors for operation at high voltage bleeder resistor should be discharged before touching them and then provided the contacts with a low short-circuit. The unloading of large capacitors via a protective resistor of sufficient voltage and pulse strength to prevent accidental arcing. Power capacitors, which do not have such a bleeder resistor, must be stored short-circuited.

Series connection / ESD

In the framework of ESD measures ( electrostatic discharge ) spoken by the leakage resistance, it is a series connection of an ohmic resistance of the same order for the derivation to earth. This series seems intuitive aggravating charge removal. However, this tentative reduction is essential in order to avoid current peaks. If the resistance significantly smaller or ideal 0 Ω, the current pulse sensitive components and assemblies destroyed safely.