Another example of the use of mercury for its ability to make and break electrical contacts. This relay contains, safely (I hope!) sealed up inside it, a considerable quantity of mercury. (So much that you can hear and feel it sloshing around if you shake the relay.) Magnetic coils, when activated, tilt the mercury chamber back and forth to roll the mercury onto or off of the electrical contacts. Of course it relies on gravity, so it has to be mounted in the correct vertical orientation, and it wouldn't work in space. There are three identical units because this relay was meant to switch industrial three-phase power, which comes on three wires.
Source: eBay seller dr.starstone
Contributor: Theodore Gray
Acquired: 20 January, 2007
Text Updated: 11 February, 2007