Ripple free DC??????

Status
Not open for further replies.
W

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.
 
WB82 said:
Anyone ever hear the phrase "ripple free DC", and what it might mean???
Click to expand...
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.
 
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.
 
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 said:
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.
Click to expand...
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....
 
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.
 
Last edited:
Besoeker said:
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.
Click to expand...

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.
 
Status
Not open for further replies.
Top