Search results
Results From The WOW.Com Content Network
A braking chopper is an magnetical switch that limits the DC bus voltage by switching the braking energy to a resistor where the braking energy is converted to heat. Braking choppers are automatically activated when the actual DC bus voltage exceeds a specified level depending on the nominal voltage of the variable-frequency drive
Schematic of an inverter using a vibrator as a chopper. In electronics, a chopper circuit is any of numerous types of electronic switching devices and circuits used in power control and signal applications. A chopper is a device that converts fixed DC input to a variable DC output voltage directly.
A blocked rotor test is conducted on an induction motor.It is also known as short-circuit test (because it is the mechanical analogy of a transformer short-circuit test), [1] locked rotor test or stalled torque test. [2]
The braking current decays, and after a delay of about 1.5 seconds the braking relay contactor opens again. At this point the motor can be restarted. In such a unit, there are typically two potentiometers, one to vary the braking torque from the firing circuit and the other to vary the timer. These settings are balanced so that braking torque ...
When the brake pipe and car components are charged with air, the brakes release. When the engineer needs to make a brake application, control valves in the locomotive reduce the brake pipe pressure. As the brake pipe pressure is reduced, the service portions on each car divert air from their reservoirs to their brake cylinders.
Any dynamic braking operation required for the motor can be realized by means of braking DC chopper and resistor shunt connected across the rectifier. Alternatively, an anti-parallel thyristor bridge must be provided in the rectifier section to feed energy back into the AC line.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Main page; Contents; Current events; Random article; About Wikipedia; Contact us; Pages for logged out editors learn more