# 3 Phase Power Meter Design ( Power supply Help)

1. ## 3 Phase Power Meter Design ( Power supply Help)

I designing a 3-phase power meter using the CS5466 IC from cirrus logic
the final design should be power by one the phases (X,Y or Z)
the target systems are 3 phases systems with neutral included ( 120 vac Phase to neutral and 240 phase to phase).
The challenge is that whatever phase is present ( i.e. x,y or z) this one should power up the system ( the ac voltage will be break down to 5 vdc).

Any help will be highly appreciate.

rlev

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2. ## 3 Phase Power Meter Design ( Power supply Help)

Is it possible to just use one of the phases, say X, to power your meter all the time?

3. ## Re: 3 Phase Power Meter Design ( Power supply Help)

You can use 3-phase rectifing bridge and then step voltage down to whatever you need using switchmode power supply.
If you do not have 3-phase bridge you can use 3 diodes connected to each phase and to one point and smoothing capacitor (HVoltage) connected between this point and neutral and step this down in the same way as before.
By using this switchmode you will isolate yourself from HV what makes this circuit safe.

4. ## Re: 3 Phase Power Meter Design ( Power supply Help)

welll the design can not depend on just one phase ( like for example X) to be powered.......the problem that i have is that wharever phase is present this phase should power up the circuit.

Long time ago i read about a 3-phase transformer that could solve my problem...but i lost the link where i found this info.

Still waiting for more suggestions.

Rlev

5. ## 3 Phase Power Meter Design ( Power supply Help)

Sorry to ask this... Why does your design can not depend on just ONE particular phase? Do you mean at certain instances, each phase has the possibility that it delivers NO POWER?

6. ## Re: 3 Phase Power Meter Design ( Power supply Help)

The design can not depend on just one specific phase because this power meter is gonna be used as part of a power distribution system which should be as flexible as possible.

Any another ideas...?

The 3 phase bridge idea seems good enough to me...but i would like to explore others altenatives.

Rlev

7. ## Re: 3 Phase Power Meter Design ( Power supply Help)

If you don't like the bridge idea than take 3 small transformers and connect all 3 outputs trough sigle diods and in this way you will have low, rectified voltage which you can use in your 5V regulator and it will be present as soon as any of three fases will be on.

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