What actually happens when u use an ac breaker in place of a DC breaker in a DC circuit

 

Depends on the nature of the load and the current value.
DC breakers often have arc suppression means after a certain current rating, particularly if used with an inductive load.
Max.

 

Depends on the nature of the load and the current value.
DC breakers often have arc suppression means after a certain current rating, particularly if used with an inductive load.
Max.

The load is a battery. I have a solar setup which generates an average of 20A. The rating of the breaker is 32A with a large voltage handling capability of 250vac (as written on it)

 

Are you using a DC breaker at the moment? If so what is the part No.?
Max.

 

You might get away with is for a few operations, then the conacts will either fall off or melt shut. 50-50 chance.

 

If you already have it, check to see if it is dual rated, as some can be.
Max.

 

All other things being equal, AC only breakers do not need as fast an action as DC breakers. AC breakers rely on the voltage dropping through zero volts in the sine wave, so using them for the same voltage means you are asking it to break the arc at full voltage and current each time.
Best case - lower number of cycles before failure.
Worst case - doesn't break the arc and the place burns down.

 

No

Are you using a DC breaker at the moment? If so what is the part No.?
Max.

No. I am not using a DC breaker.all I have is an ac breaker

 

What is the style/type/part No.?
Max.

 

So I just shouldn't use it at all..?

 

It is generally more critical with DC Inductive loads.
Max.

 

What is the style/type/part No.?
Max.

SH 201L

 

It is generally more critical with DC Inductive loads.
Max.

Why would you say so?

 

Why would you say so?

Inductive load release the stored energy when the current is terminated and can cause arc over of contacts etc.
When ever using a device out of its manuf. specifications you take a chance on whether a problem is going to occur or not.
Max.

 

An inductive load is like a wound up spring - break the circuit and the energy stored in that spring tries to get across that opening breaker.
It's similar to water hammer in a plumbing system.

 

All other things being equal, AC only breakers do not need as fast an action as DC breakers. AC breakers rely on the voltage dropping through zero volts in the sine wave, so using them for the same voltage means you are asking it to break the arc at full voltage and current each time.
Best case - lower number of cycles before failure.
Worst case - doesn't break the arc and the place burns down.

SparkysLab is essentially correct – the principle difference between an ac and dc switch/breaker is that the action of the contact breaking/making is independent of the speed of the switch action. This is by design because the dc switch is always switching and maximum voltage. Slow switching will result in extended arcing and a very short switch/breaker life.

If you do use an ac only rated switch/breaker on a dc circuit – when operating the switch/breaker make your switching action as fast as possible (to extend its life), especially when switching off.

 

Where do you plan on putting the breaker - between the solar array and the battery or between the battery and the load?
What is the battery voltage?

[EDIT:] If the breaker is between the solar array and the battery, what is the intent - to protect the battery from excessive current or to prevent excessive current from the battery in the event of failure of the diodes normally in series with the solar panels?

 

QUOTE="ebp, post: 1265661, member: 517558"]Where do you plan on putting the breaker - between the solar array and the battery or between the battery and the load?
It is in between the pv modules and the charge controller to actually switch off the power from the panels to the controller. There's actually a reason for that

 

SparkysLab is essentially correct – the principle difference between an ac and dc switch/breaker is that the action of the contact breaking/making is independent of the speed of the switch action. This is by design because the dc switch is always switching and maximum voltage. Slow switching will result in extended arcing and a very short switch/breaker life.

If you do use an ac only rated switch/breaker on a dc circuit – when operating the switch/breaker make your switching action as fast as possible (to extend its life), especially when switching off.

I'll definitely have to look up an article on breakers..seem totally lost. Really don't know how they operate. A link will be much appreciated

 

Since you didn't tell us anything about voltage, it still isn't clear if the breaker might be OK.

The maximum power that the breaker has to interrupt is finite. The current is limited to the short-circuit current from the PV array (which would be too low to ever trip a 32 A breaker if the MPP current from the array is 20 A). The voltage across the contacts as it opens will very likely be much lower than the system voltage - the charge controller probably has substantial capacitance at the input, which will essentially "fix" the voltage on one side of the breaker. The other side could rise to the open-circuit voltage of the array during opening.

Many ordinary relays rated for 250 VAC will be rated for 30 VDC at the same current. There is no reason to believe the breaker would be less capable than a relay.