Search results
Results from the WOW.Com Content Network
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 ...
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] From this test, short-circuit current at normal voltage , power factor on short circuit, total leakage reactance , and starting torque of the motor can be found.
For the tests the vehicle brake for which the replacement linings are designed is installed in an inertia dynamometer instrumented for continuous recording of rotative speed, brake torque, brake line pressure, number of rotations after brake application, braking time, and brake rotor temperature. [1]
When considering torque, the question of using dynamic or static torque for the application is key. For example, if a machine is running at a relatively low rpm (5–50 depending upon size) then dynamic torque is not a consideration since the static torque rating of the coupling will come closest to where the application is running.
Maximum brake torque (MBT) is the use of optimal ignition timing to take advantage of an internal combustion engine's maximum power and efficiency. There is always an optimal spark timing for all operating conditions of an engine. MBT is ideal at wide-open throttle (WOT), but not desirable when the engine is at idle.
Direct torque control (DTC) is one method used in variable-frequency drives to control the torque (and thus finally the speed) of three-phase AC electric motors.This involves calculating an estimate of the motor's magnetic flux and torque based on the measured voltage and current of the motor.
The torque is then related to the lever length, shaft diameter and measured force. The device is generally used over a range of engine speeds to obtain power and torque curves for the engine, since there is a non-linear relationship between torque and engine speed for most engine types. Power output in SI units may be calculated as follows:
In vector control, an AC induction or synchronous motor is controlled under all operating conditions like a separately excited DC motor. [21] That is, the AC motor behaves like a DC motor in which the field flux linkage and armature flux linkage created by the respective field and armature (or torque component) currents are orthogonally aligned such that, when torque is controlled, the field ...