# TRIAC amperes

Discussion in 'General Electronics Chat' started by Irmutis, Feb 28, 2010.

1. ### Irmutis Thread Starter Member

May 24, 2009
17
0
Hi,

I am using TRIAC to control heating element (8 kW). Power supply is 220 V , 50Hz. What is on state current for this TRIAC?

2. ### hgmjr Moderator

Jan 28, 2005
9,030
214
TRIAC devices are not standardized. To answer this question, a part number is needed.

hgmjr

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Apr 5, 2008
15,796
2,382
Hello,

8kW on 220 Volts? that is almost 40 Amps.
This will not work on a standard line (that is 25 A in Holland).

Greetings,
Bertus

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4. ### Irmutis Thread Starter Member

May 24, 2009
17
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40 A for DC (P=U*I) ,but not for AC. I need to find out how many ampers do I need for the load and when I will know it, i will chose TRIAC. So I need help to find current.
I know what what formula for AC power is P=U*I*cosfi (cosfi is power factor)

5. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Well, 8000 watts and 220 VAC means on the order of 36.36 amps. As the voltage is ACRMS, so is the current. Peak is on the order of 1.4 times the RMS value, or 50.9 amps.

For some overhead capacity, such as sagging line voltage, you need more current capacity. Going 50% over probably won't be that costly.

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6. ### Irmutis Thread Starter Member

May 24, 2009
17
0
To me it is hard to believe what I need about 40 A current.
For example, if at home I am using an iron (2000W) , so it means, it takes about 10A current...?

7. ### andrew24 Active Member

Aug 20, 2008
76
0
yes, current can be measured peak-to-peak, or RMS, but isn't there that several types of power exist(active, or real; reactive and full) and when we're using formula P=U*I we calculate full power, which is active+reactive?