Ripple free DC??????

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WB82

Member
Location
Pennsylvania/GOM
Anyone ever hear the phrase "ripple free DC", and what it might mean???We work on a drilling rig that doesn't follow any one particular code, NEC, IEC, BS, ABS, Coast Guard, you name it we've heard em all, this was on a procedure from our owners in Norway. Thanks much.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Anyone ever hear the phrase "ripple free DC", and what it might mean???
It means pure DC, as from a battery or a well-filtered AC-to-DC power supply.

Ripple refers to the remnants of AC that squeak through poorer-quality supplies.
 

kbsparky

Senior Member
Location
Delmarva, USA
You can make DC out of AC using a simple bridge rectifier. Add a nice-sized capacitor, and you can smooth out many of the ripples (or pulsating DC) quite easily.
 

Besoeker

Senior Member
Location
UK
We have designed and manufactured rectifier systems for telecoms power suoolies. These were fairly low voltage (50V) but quite high current at 1200Adc. The permitted ripple voltage had to fall within a psophometrically weighted curve which required not more than 2.0mV at certain frequencies. They were SCR controlled rectifiers with serious inductive and capacitive filtering. Big expensive components - not the kind of thing you want to get wrong at the design stage.
 

Besoeker

Senior Member
Location
UK
We have designed and manufactured rectifier systems for telecoms power suoolies. These were fairly low voltage (50V) but quite high current at 1200Adc. The permitted ripple voltage had to fall within a psophometrically weighted curve which required not more than 2.0mV at certain frequencies. They were SCR controlled rectifiers with serious inductive and capacitive filtering. Big expensive components - not the kind of thing you want to get wrong at the design stage.
Anyway, 2.0mV ripple, although not ripple free, is pretty close to it.
We had another project for a DC power supply that was specified at 750V, 300Adc and a peak to peak ripple voltage of just 2.5mV. That was a bit of a challenge....
 

G._S._Ohm

Senior Member
Location
DC area
With the engine running even your car battery is not ripple free.

There is or was a gadget that troubleshoots your auto electrical system by just plugging it into the cigarette lighter. High ripple may mean faulty alternator diodes or a battery with high internal resistance because it is sulphated.
You can probably pick up this ripple with a DVM set on the AC volts range but I don't know the pass/fail limits.
 
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Open Neutral

Senior Member
Location
Inside the Beltway
Occupation
Engineer
We have designed and manufactured rectifier systems for telecoms power suoolies. These were fairly low voltage (50V) but quite high current at 1200Adc. The permitted ripple voltage had to fall within a psophometrically weighted curve which required not more than 2.0mV at certain frequencies. They were SCR controlled rectifiers with serious inductive and capacitive filtering. Big expensive components - not the kind of thing you want to get wrong at the design stage.

I can imagine.... A friend was a design engineer at Lorain Products back when they were the name in telco power supplies. He tells interesting stories.
 
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