One is the shield or chassis ground, while the other two are signal connections.

Chassis ground wire: a larger diameter wire was installed.

Some TV designs only require polarizing the plug, while others require rewiring the power supply to remove the switch from chassis ground.

Common Chassis Ground - isolation between circuit common and chassis (chassis grounded).

The inverted Y is also called a ground dome; note that the two bottom legs terminate in different ground levels, such as chassis ground and signal ground.

Since input terminals of instruments may have one side of the current loop input tied to the chassis ground (earth), analog isolators may be required when connecting several instruments in series.

It is sprayed on to the enclosure and, once dry, produces a continuous conductive layer of metal, which can be electrically connected to the chassis ground of the equipment, thus providing effective shielding.

A broad black band was applied to some tubular paper capacitors to indicate the end that had the outer electrode; this allowed this end to be connected to chassis ground to provide some shielding against hum and noise pickup.