Understanding Power Ratings on Resistor: Will 50V DC Harm It?

  • Thread starter Thread starter IronHamster
  • Start date Start date
  • Tags Tags
    Dc Power Resistor
Click For Summary
SUMMARY

The discussion centers on the power ratings of a resistor purchased from RadioShack, specifically its ability to handle 50V DC. The resistor has a voltage rating of 800V and a power rating of 25W. Operating the resistor at 50V results in a calculated power dissipation of 5.3 kW, which far exceeds its 25W rating, indicating that it would likely fail catastrophically if used under these conditions. The discrepancy between voltage and power ratings is clarified, emphasizing that the 800V rating pertains to high-value resistors and short-duration pulses, not continuous operation.

PREREQUISITES
  • Understanding of resistor power ratings and voltage ratings
  • Basic knowledge of Ohm's Law and power calculations
  • Familiarity with resistor types and their specifications
  • Knowledge of electrical safety and component limits
NEXT STEPS
  • Research "Ohm's Law and power dissipation calculations"
  • Learn about "resistor voltage ratings and breakdown voltage"
  • Explore "thermal management in resistors and power handling"
  • Investigate "different types of resistors and their applications"
USEFUL FOR

Electronics enthusiasts, electrical engineers, and anyone involved in circuit design or component selection who needs to understand resistor specifications and safe operating limits.

IronHamster
Messages
28
Reaction score
0
I recently bought this resistor:

http://www.radioshack.com/product/index.jsp?productId=12573233

I want to hook it up to about 50V DC, but I want to know if this would be harmful to the resistor. According to the description it can handle up to 800V, but its power rating is only 25W. This doesn't make sense to me, because according to that power rating even a 9V battery would break it.

Anyone know how to reconcile the two? Would 50V be okay?
 
Engineering news on Phys.org


These resistors come in a wide range of values. The "800V" rating would only make practical sense for the high values resistors and for short duration voltage pulses, so the average power stayed within the 25W power rating.

Alternatively the 800V might be the breakdown voltage between the actual resistor and the outside of the casing. (In other words it would be OK if one end of the resistor was at 800V above ground potential and the other end was 799V above ground).

http://www.nteinc.com/resistor_web/pdf/twentyfive.pdf

At 50V DC the power dissipation would be 50^2 / 0.47 = 5.3 kW, so a 25W resistor isn't going to last very long. It mgiht explode rather than just catching fire, operated so far outside its power rating.
 


Ah, I understand perfectly. Thanks Aleph!
 

Similar threads

What Happens When AC and DC Signals Interact in Audio Circuits?
  • · Replies 13 ·
Replies
13
Views
3K
Buck converter will power LED's but voltage divider will not....
  • · Replies 4 ·
Replies
4
Views
3K
Could you use Solar to power a DC to AC Inverter? (Description below)
  • · Replies 6 ·
Replies
6
Views
4K
Choosing the Right Resistor for a 6V DC Motor Running on a 9V Battery?
  • · Replies 3 ·
Replies
3
Views
2K
Understanding High Power Resistor Ratings: A Beginner's Guide
  • · Replies 2 ·
Replies
2
Views
2K
What Wattage Rating Is Needed for a 33Ohm Resistor in a 9V, 1A Circuit?
  • · Replies 78 ·
3
Replies
78
Views
10K
Help on Circuit for providing usable DC power, from solar batteryarray
  • · Replies 3 ·
Replies
3
Views
2K
Protection on Step up and Step Down Converter Module Bucks
  • · Replies 1 ·
Replies
1
Views
2K
How to make a custom UPS using an old PC power supply and 18650 batteries?
  • · Replies 7 ·
Replies
7
Views
3K
Selecting the correct power source for a Cockroft-Walton Multiplier
  • · Replies 1 ·
Replies
1
Views
2K