Shunt
Shunt turns up in 2 fields: corrosion, railroad. Here is what it means to the people in each one.
Shunt in corrosion
Precision low-resistance resistor in a CP circuit, used to measure current from the voltage across it.
A calibrated resistor of known low value placed in the rectifier output, anode leads or bonds. Reading the millivolt drop across it and applying its factor gives the current without breaking the circuit. Rectifier shunts are rated by current and millivolts, such as 25 A at 50 mV, a factor of 0.5 A per mV, and using the wrong factor is one of the commonest sources of bad current data.
"Shunt reads 31 millivolts and it's a 50 amp 50 millivolt shunt, so the rec is putting out 31 amps."
Shunt in railroad
The electrical connection made across the rails by a train's wheels and axles.
The electrical short circuit created when a solid metal wheelset bridges the two rails of a track circuit. This connection drops the track relay, indicating to the signal system and dispatcher that a train occupies the block. If a train fails to shunt the track due to rust or sand, the system may falsely show the block as clear.
"That rusty spur track won't hold a shunt, so don't trust the signals if you leave a cut of cars out there."