Glossary as bellow:
	
	
		Vs
	
	
		D.C. Spark-over Voltage
	
	
		The voltage at which the GDT sparks over with slowly increasing d.c. voltage.
	
	
		 
	
	
		V
	
	
		Impulse Spark-over Voltage
	
	
		The highest Voltage which appears across the terminals of a GDT in the period between the application of an impulse of given wave-shape and the time when current begins to flow.
	
	
		 
	
	
		Va
	
	
		Arc Voltage
	
	
		Voltage drop across the GDT during arc current flow.
	
	
		 
	
	
		Vgl
	
	
		Glow Voltage
	
	
		The peak value of the voltage drop across the GDT when a glow-current is flowing, It is sometimes called the glow mode voltage.  
	
	
		 
	
	
		8/20 ¦Ìs
	
	
		8/20 Current Impulse
	
	
		Current impulse with a nominal virtual front time of 8 ¦Ìs and a nominal time to half-value of 20 ¦Ìs.
	
	
		 
	
	
		1.2/50 ¦Ìs
	
	
		1.2/50 Voltage Impulse
	
	
		Voltage impulse with a nominal virtual front time of 1.2 ¦Ìs and a nominal time to half-value of 50 ¦Ìs.
	
	
		 
	
	
		I
	
	
		Alternating Discharge Current
	
	
		The r.m.s. value of an approximately sinusoidal alternating current passing through the GDT.
	
	
		 
	
	
		In
	
	
		Nominal Discharge Current
	
	
		Crest value of the current through the GDT having a current waveshape of 8/20 ¦Ìs.
	
	
		 
	
	
		Imax
	
	
		Maximum Discharge Current
	
	
		Crest value of a current through the GDT having an 8/20 ¦Ìs waveshape and magnitude according to the manufacturers specification. Imax is equal to or greater than In.