You might be surprised to learn that hand-held semiconductors testers often do not have the capability to accurately test "sensitive gate" thyristors and Triacs. Typically, these instruments provide only one gate current level regardless of device. Although a higher than specified current would fire a sensitive gate device, there’s no guarantee that it will operate normally when in circuit.

Paradoxically, many testers do not provide high enough gate current to reliably trigger some larger devices. The test current used (anode to cathode or MT1 to MT2) may also be too low, particularly as the instrument’s battery voltage declines.

Reliable testing

Peak has addressed these issues and eliminated the guesswork with the Atlas SCR. Devices are tested with up to eight discrete gate current levels (100μA, 500μA, 2.5mA, 10mA, 25mA, 50mA, 75mA & 90mA). Naturally, testing starts at the lowest level and progress towards the higher levels, ensuring that the minimum necessary trigger current is used.

Note: Triacs are tested in both quadrants 1 and 3 but only the gate current for quadrant 1 is displayed.

To ensure consistent results, test current is fixed at 100mA (nominal) regardless of battery condition and is applied as 100μs pulses. This eliminates the possibility of damage to sensitive devices.