Hydrogen Gas-Cooled Generator Seals and Feedthroughs

Product Description

Generators provide energy by transforming kinetic energy from turbines into electrical energy. A byproduct of this process is heat, which results in the need for cooling the generator. This is especially so in the case of large power generators. One highly efficient cooling process for large power generators involves the use of Hydrogen (H2). This gas has very good heat removal properties when used as a coolant. However, it is also a highly explosive gas.

We provide safe flange-type electrical feedthroughs for instrumentation and control purpose, as well as thermocouple feedthroughs or combinations of both, to enable the productivity of energy facilities for many decades. These are also referred to as lead-through plates.

SCHOTT’s Eternaloc hydrogen generator seals and feedthroughs consist mainly of:
  • A steel flange with nickel-iron conductors sealed in by means of compression-seal technique
  • standard electrical feedthroughs with 1 to 406 conductors, allow an optimized construction of the generator’s vessel
  • standard thermo-couple lead-through plates up to 121 thermo-couples
  • sealing between the lead-through plate and the generator, usually accomplished by an O-ring



SCHOTT’s hydrogen generator seals and feedthroughs (or lead-through plates) provide a number of unique product features including:
  • inorganic , non-aging technology
  • maintenance-free
  • hermetically sealed and thus leak-tight by 10-8 mbar.l/s

Additionally, the high conductor density (with up to 406 conductors per penetration) allows for a reduction in the quantity of penetrations needed.


Hydrogen gas-cooled generator lead-through plates are required in any type of power plant with high power electrical generators.

Technical Details


The glass preform, metal shell and conductor pins or tubes for thermo-couples, made of a nickel-iron alloy, are assembled on a fixture. The complete assembly is heated to a temperature where the glass becomes free flowing and fills all the gaps between the metal parts.

During the cooling process, the glass solidifies at its set point. Upon further cooling, the outer metal housing shrinks more than the glass seal (due to its higher coefficient of thermal expansion), leading to a compressive radial force onto the glass body. This leads to an increased hermeticity and tightness even under high temperature or gas pressure.

After sealing, the parts are cleaned. Standard plating for the flanges is nickel over copper plating.

Features / Specifications

SCHOTT's electrical lead-throughs operate up to
  • 10 bar design pressure (higher pressure can be requested)
  • 400 volt working voltage
  • EEx e certified versions are possible upon request

Forms of Supply and Product Packaging

We can deliver the feedthroughs in accordance to customers’ dimensional requirements. Upon request, we can also deliver sockets and o-rings.
Our products are delivered in dust-safe, moisture-safe, impact-proof transportation boxes.


SCHOTT Eternaloc lead-through plates are manufactured in our ISO 9001 certified plant. EEx e certified versions are possible upon request.

In addition to standard testing procedures, the pressure and gas tightness, as well as the electrical properties are stringently checked. For more information, please refer to our quality assurance process.
Trade Fairs & Events
Trade fair CIOE - China International Optoelectronic Exposition, Shenzhen, China, 01.09 - 03.09.2021
Trade fair Gastech, Singapore, Singapore, 13.09 - 16.09.2021
Trade fair Battery Experts Forum, Frankfurt, Germany, 05.10 - 07.10.2021
Christoph-Dorner-Strasse 29
84028 Landshut
E-Mail to SCHOTT+49 (0)871/826-0