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What is holding current in triac?
This minimum current which keeps the TRIAC conducting is called the hypostatic or holding current, IH. After the TRIAC is turned on, a current, IT, flows through it. When the TRIAC current falls below the holding current the TRIAC is blocked and requires another gate pulse before it can turn on again.
How much current can a triac handle?
Triacs are available that can handle currents (usually measured in rms values) as high as 25 amperes. By comparison, SCRs can be readily obtained with current ratings (usually expressed as average values for a half cycle) as high as 700 or 800 amperes, and some are rated even higher.
What is meant by holding current?
The holding current (hypostatic) for electrical, electromagnetic, and electronic devices is the minimum current which must pass through a circuit in order for it to remain in the ‘ON’ state. The term can be applied to a single switch or to an entire device.
What is the latching current of a TRIAC?
The latching current (IL) of a TRIAC is the minimum value of the load current (current flowing between electrodes A2 and A1) that keeps the device conducting when the gate signal is removed (see Figure 1).
Where does the name TRIAC come from in electronics?
TRIAC, from triode for alternating current, is a generic trademark for a three terminal electronic component that conducts current in either direction when triggered.
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.
What should the gate threshold current be in TRIAC?
The minimum current able to do this is called gate threshold current and is generally indicated by I GT. In a typical TRIAC, the gate threshold current is generally a few milliamperes, but one has to take into account also that: