Gas discharge tubes protect for IEC 62368-1

The bidirectional GDT28H series has devices with breakdown voltages from 1 to 3.3kVdc, and all are 8mm in diameter and 6mm long, with out without axial leads.

Picking the nominally 2kV GDT28H-200 as an example, breakdown is between 1,600 and 2,400V (100V/s). Arc voltage is typically 25V at 1A.

Nominal impulse discharge is 5kA (8/20µs, 10 operations), or 10kA max (2 operations).

“An increasing range of electrical and electronic equipment is required to meet electrical safety standards such as the IEC 62368-1,” said the company, An “advantage of the Model GDT28H Series is its suitability for use in ac isolation solutions, achieved through a combination of its operating voltage range, insulation resistance and surge rate”.

According to the data sheet, insulation resistance for all devices is 10GΩ at 100V (<1.5pF max at 1MHz), and the 2kV example sparks over at 2,500V at 100V/μs, or 2,750V at 1kV/μs. Operation is over -40 to +125°C.

Few surge protection components can handle the several-thousand-amp surges typically of ac mains lines, said Bourns, explaining that both MOVs and gas discharge tubes can survive high surge currents, the difference being that GDTs trigger and then conduct with a few tens of volts across them, while MOVs clamp at a high voltage. This leads to higher instantaneous power in MOVs, allowing discharge tubes to be smaller for a given protection voltage and surge capability.

The GDT28H gas discharge tube product page can be found here, and the data sheet here.