I have come across the following half bridge rectifier circuit connected across phase R and T.

enter image description here

I'm wondering about the large resistor network in parallel with the source. What is the point of this and is there any benefits to it?


  • \$\begingroup\$ My first response was to recognize that the circuit uses pairs of everything. Sometimes that makes sense (single point failure?) But 20 resistors like that? I can only imagine that there is a high voltage present at the input and the resistors aren't rated high enough unless they are chained up like that. Be interesting to hear a better analysis. \$\endgroup\$
    – jonk
    Apr 17, 2018 at 8:38
  • \$\begingroup\$ @jonk even with the equivalent rated single resistor I fail to see what effect it will have on the circuit. The voltage will be the same across it. \$\endgroup\$
    – MXG123
    Apr 17, 2018 at 13:05

1 Answer 1


The resistors are there to cut the inductive spikes when D022 and D023 are reverse biased. The parallel-serial is to minimize the effect of a failing resistor and also to split the voltage across resistors with lower voltage rating.

The overall resistance is Rt = 680k * 10 / 2 = 3.4M

Voltage per resistor Vr = 0.1 *V

In case of a failing resistor

Rt =680k + 680k * 9 / 2 = 3.7M

Voltage over the remaining resistor

Vr = V * 680 / 3700 = 0.18 * V

  • 1
    \$\begingroup\$ that makes sense \$\endgroup\$
    – MXG123
    Apr 20, 2018 at 7:24

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