Peak Atlas DCA Pro
User Guide
June 2019
–
Rev 1.7
Page 28
Thyristors (SCRs) and Triacs
Sensitive low power thyristors (Silicon Controlled
Rectifiers - SCRs) and triacs that require gate
currents and holding currents of less than 10mA
can be identified and analysed with the
DCA Pro
.
Thyristor terminals are the anode (A), cathode (K) and the gate (G).
This example shows that a thyristor has
been detected:
Triac terminals are MT1, MT2 and gate
(the letters MT stand for main terminal).
MT1 is the terminal with which gate
current is referenced.
The unit determines that the device under test is a triac by checking the
gate trigger quadrants that the device will reliably operate in. Thyristors
operate in only one quadrant (positive gate current, positive anode
current). Triacs can typically operate in three or four quadrants, hence
their use in AC control applications.
The gate trigger currents used by the
DCA Pro
are limited to less than
10mA. Some thyristors and triacs will not operate at low currents and
these types cannot be analysed with this instrument. Note also that if
only one trigger quadrant of a triac is detected then the unit will
conclude that it has found a thyristor. Please see the technical
specifications for more details. The
Atlas SCR
(model SCR100)
instrument is designed for analysing triacs and thyristors that require
currents up to 90mA to operate.
