# Arrangement of discharge resistors for capacitors in series

These 2 circuits consist of voltage source, 2 capacitors in series and their discharging resistors.

Capacitors C1 and C2 are put in series because voltage V1 is higher than rated voltage of each capacitor. Nominal values of capacitors and resistors are the same (C1 = C2, R1 = R2). Only difference between both circuits is the link between points A and B. simulate this circuit – Schematic created using CircuitLab

In case that the real values of R and C match their expected nominal values, both circuits should behave in the same manner, since there is no voltage difference between points A and B.

However, if, for example, capacitance of C2 drops due to wear and voltage in point A increases, there will be (initially) a voltage difference between points A and B. That higher voltage could possibly further damage the capacitor. In case of Circuit 2, current will flow through the link A-B and the circuit will eventually reach an equilibrium, where the voltage on the A-B link will be V/2 (if R1 = R2). This could (possibly) prevent the capacitor C2 from total failure due to overvoltage. Therefore, from this point of view, I would say it is better to add the A-B link, as shown in the Circuit 2.

My question is, could there be any negative effects of adding the A-B link?

• There cannot be a voltage difference between points A and B - they are connected by a short circuit. – Chu Sep 5 '19 at 16:22
• In Circuit 1 there will be a voltage difference. In Circuit 2 of course not, but there will be current flowing through the link before the circuit reaches an equilibrium state. – simonov Sep 5 '19 at 16:26
• If C1 = C2 and they are not leaky then voltage at point A will be 1/2 V1 = B. The short from A to B insures the voltages will be the same even if components drift. – Rob B. Sep 5 '19 at 17:14
• meant ensures not insures – Rob B. Sep 5 '19 at 17:19