DC Grounding Circuit Undrestanding

[mostatab]

Hi,
I'm inspecting an industrial PCB which use 8 VAC voltage as input. Then a diode bridge is used in order to rectify this voltage. I've found they have used the attached circuit for the DC part of the power supply. However, I couldn't understand why they use such circuit.
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Could you please explain why these circuit is used?

Thanks

[TimFox]

Are you sure that the three symbols for DC power, Ground, and Earth are correctly drawn?  The circuit that you show (by itself) makes no sense.

[mostatab]

Are you sure that the three symbols for DC power, Ground, and Earth are correctly drawn?  The circuit that you show (by itself) makes no sense.

Yes, my apology. the used symbols are not correct. the GND net is connected to negative pad of the bridge, and the Earth is connected to the chassis.

[TimFox]

Well, C19 and C20 bypass the DC output nodes of the bridge to Earth/Chassis.  The diode might prevent reverse voltage under fault conditions.  C21 might be a filter capacitor (is the negative terminal of the bridge grounded elsewhere?), and the resistor a bleeder on C21.

[radiolistener]

Yes, my apology. the used symbols are not correct. the GND net is connected to negative pad of the bridge, and the Earth is connected to the chassis.

there is no bridge on your schematic