Different electric circuits for triggering the switch with a trigger unit based on an auxiliary glow discharge are discussed. Most attention is concentrated on the recent experimental results on low voltage triggering of the switch and on the mechanisms for the main discharge initiation under the action of the trigger pulse. Due to modifications in the trigger electric circuit, the switch is triggered starting from a voltage of 50 V at a current level in the trigger circuit of 10 mA. With a voltage of 200-250 V and a trigger current of about 0.25 A, the delay time to triggering does not exceed 200 ns.
