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Which is the minimum current required to turn on a TRIAC?
The minimum gate current required to turn on a triac is called gate triggering current IGT. This needs to be applied across the gate and the A1 terminal of the Triac which is common to the gate trigger supply. The gate current should be higher than the value rated for the lowest specified operating temperature.
What do voltage spikes on a TRIAC mean?
Voltage spikes across the triac indicate intermittent power driving the solenoid valves which may not allow the solenoids to operate properly. When the gate trigger current is increased further the voltage spikes become more severe. At a trigger current of 17.2mA the triac is only active for half a cycle (Figure 12 and Figure 13).
What causes the TRIAC to conduct in both directions?
A small leakage current flows through the device until it is triggered by breakover voltage or gate triggering method. Hence the positive or negative pulse to the gate triggers the triac in both directions. The supply voltage at which the triac starts conducting depends on the gate current.
How is a TRIAC similar to a latching relay?
A triac can be compared to a latching relay. It will instantly switch ON and close as soon as it’s triggered, and will remain closed as long as the supply voltage remains above zero volts or the supply polarity is not changed.
Where are the gate and anode terminals located in TRIAC?
The terminals are marked as MT1, MT2 as anode and cathode terminals in case of SCR. And the gate is represented as G similar to the thyristor. The gate terminal is connected to both N4 and P2 regions by a metallic contact and it is near to the MT1 terminal.
What is the trigger voltage of a TRIAC?
The trigger voltage applied across the gate and the A1 terminal of a triac is referred to as VGT. It is applied through a resistor which will discuss shortly. The gate current that effectively latches a triac is the latching current and is given as LT.
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