×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

TRIAC MOTOR CONTROL

TRIAC MOTOR CONTROL

TRIAC MOTOR CONTROL

(OP)
I am controlling a 220v AC 1/8 HP motor with a TRIAC circuit. When the TRIAC goes off, every cycle, the 220v are applied over the gate circuit. These is a resistive circuit. I am using low power resistors (1/4 watt) with succes, but i think these resistors might burn in the future. I would appreciate if someone knows if these resistors are going to resist or if i should try another way to trigger the TRIAC. I couldn“t find any document about resistor ratings, for example peak dissipation vs time. Perhaps if i put 1 watt or 2 watt resistors that should be enough to be sure that there is not going to be any trouble, but maybe not. Thanks in advanced for any advice.

RE: TRIAC MOTOR CONTROL

You should not be appying 220VAC to the gate circuit on a triac, i will self destruct very quickly. Do you have a circuit of what you are doing? if so can you email it to me at mark_empson at hotmail.com and I will see if I can help.
Best regards,

Mark Empson
http://www.lmphotonics.com

RE: TRIAC MOTOR CONTROL

what kind of control are you trying to do ?
no problem in drive it directly from the mains... with a limiting resistor of course.
just see the triac specs and calculate the resistor power dissipation from the Gate current.

RE: TRIAC MOTOR CONTROL

Mwolf:

Since you are not specific about your circuit it is difficult to say yes or not.
If you are connecting the resistor between the gate and the anode of the Triac then you do not have problem.
You are feeding the necessary current to turn the Triac on, that maybe in the range of about 20 or so milliamps then tehTriac fires and places just about 2 to 3 volts across the resistor.

To calculate the power dissipation, determine the Triac triggering gate current and the voltage that the resistor sees until it triggers ( this will give you the time that the resistor receives heating power), then a multiply by 120 pulses to attain the total used time .

Regards

Nando

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources