Maximum surge - ON state Current (I
msc
)
It is the maximum admissible peak value of a sinusoidal half cycle of tem milliseconds duration at a
frequency of 50Hz.
Latching Current (I
I
)
It is the minimum current, which is required to latch the device from its OFF state to its ON state. In other
words, it is the minimum current required to trigger the device.
Holding Current (I
H
)
It is the minimum current required to hold the SCR conducting. In other words, It is the minimum current,
below which the device stops conducting and returns to its OFF state.
Gate Current:
The current which is applied to the gate of the device for control purposes is known as gate current.
Minimum Gate Current:
The minimum current required at the gate for triggering the device.
Maximum Gate Current:
The maximum current which can be applied to device safely. Current higher than this will damage the
gate terminal.
Gate Power Loss:
The mean power loss, which occurs due to flow of gate current between the gate and the main terminals.
Turn ON time:
The time taken by the device before getting latched from its OFF state to ON state. In other words, it is
the time for which the device waits before achieving its full conduction. Usually it will be 150 to
200μsec.
Turn OFF time:
After applying reverse voltage, the device takes a finite time to get switched OFF. This time is called as
turn-OFF time of the device. Usually it will be
200μsec.
Rate of rise of current (dI/dt)
The rate at which the current flowing in the device rises is known as its rate of rise (dI/dt) of current.
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