Gas discharge tube (GDT)

01

Pick the DC and impulse sparkover voltage

Bourns' 2027 series datasheet lists DC sparkover voltages from 75 to 600 V measured at 100 V/s, with ±15% tolerance (±20% for the 75 and 90 V models). Impulse sparkover is higher and rises with the voltage ramp: the 230 V model lists 450 V at 100 V/µs and 675 V at 1,000 V/µs; the 600 V model lists 850 V and 1,100 V. Test methods follow ITU-T K.12, IEEE C62.31 and IEC 61643-311. [1]

The 2049 medium-duty series spans 75 to 600 V DC sparkover at ±30%, with impulse sparkover under 500 V at 100 V/µs and under 700 V at 1,000 V/µs for the 230 V model. [2]

Editorial calculation: a 2027-23 at 230 V ±15% may spark over as low as 195.5 V, so it clears a 150 V peak line with about 45 V margin; after life Bourns allows ±20%, giving 184 V. Check the minimum, not the nominal, against your peak working voltage including ringing signals. [1]

Give the supplier the DC sparkover voltage and tolerance, impulse sparkover limit at your rise time, surge waveforms and operation counts (8/20 µs, 10/350 µs, 10/1000 µs), alternating current rating, insulation resistance, capacitance, holdover voltage on your line, two or three electrodes, leaded or SMD, size, UL recognition and quantity.

02

Check surge rating, insulation resistance, capacitance and holdover

The 2027 lists impulse discharge current of 25,000 A 8/20 µs for one operation, 10,000 A for ten, 2,000 A 10/350 µs for two and 500 A 10/1000 µs for 400 operations; alternating discharge of 65 A rms for 11 cycles; insulation resistance over 10⁹ Ω; capacitance under 1 pF at 1 MHz; arc voltage about 10 V; and DC holdover under 150 ms on a 135 V network. It measures 8 mm in diameter by 6 mm long and works from −55 to +125 °C. [1]

The 2049 lists 20,000 A 8/20 µs once and 15,000 A ten times, 100 A 10/1000 µs for 500 operations, insulation resistance over 10 GΩ and capacitance under 1.5 pF, also in an 8 × 6 mm body. [2]

Editorial note: holdover matters because a tube that stays in its arc state at about 10 V after a surge can hold a powered line short; ask for the holdover test with your line voltage and source current. [1]

03

Use a discharge tube on mains in series with a varistor

Mitsubishi Materials' DA53 series is a micro-gap discharge surge absorber, 5.3 mm in diameter and 10 mm long, weighing 0.75 g, for protecting power supplies from power-line surges. It lists DC spark-over voltages from 350 V (280–420 V) to 7,800 V (6,240–9,360 V), insulation resistance of at least 100 MΩ, capacitance of 1 pF maximum at 1 kHz, surge current capacity of 3,000 A 8/20 µs (2,500 A for the 4,500 V part), a surge life test of 300 operations at 100 A 8/20 µs, an operating temperature range of −40 to +125 °C and storage from −55 to +125 °C. Its UL 1449 recognition applies when the part is connected in series with a varistor of at least 5 mm diameter and V1mA of 270 V or more on 125 V AC lines, or 470 V or more on 250 V AC lines; higher-voltage parts carry AC withstand ratings from 1,000 V for one minute up to 4,000 V for one minute. [4]

Editorial calculation: a 250 V AC line peaks at about 354 V (250 × 1.414), above the 280 V lower limit of the DA53-351M, so the tube alone could fire on the supply voltage and then hold the line in its arc state; the series varistor with V1mA of 470 V or more blocks that follow current, which is why the listing depends on it. It is the same minimum-against-peak check made above for Bourns' 230 V GDT on a 150 V peak line. [4] [1]

04

Compare what suppliers offer

The manufacturer card below states what the reviewed source shows.

Ask each supplier for the datasheet listing sparkover tolerance before and after life, surge ratings with waveform and operation count, and the test standard used. [1] [2] WAYON lists GDT among its main products. [3]

05

Trace what each part controls

This is a functional reference built from the sources cited; it is not a full specification.

06

Fill the specification fields with values for your design

A GDT quotation needs values for your design. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the voltage, surge and line data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

DC sparkover: [V; tolerance]
Impulse sparkover: [V at V/µs]
Surge: [kA; waveform; operations]
AC discharge: [A rms; time]
IR/capacitance: [Ω; pF]
Holdover: [line V; source A]
Form: [2 or 3 electrode; leaded; SMD; size]
Quantity: [units]

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