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Chapter 1 - System Overview
Medha Servo Drives Pvt Ltd.
respect to the time or phase relationship. The phase relationship depends on
the speed of the Rotating Field with respect to the Rotating speed of the
Rotor. If Rotor speed lags Field speed, Voltage and Currents are nearly in
phase and Power flows into the Motor most of the time. If Rotor Speed
exceeds Fields speed, Voltage and Current are out of phase by nearly 180
degree and Power flows out of the Motor most of the time.
1.2.2 Alerter/VCD System
The Alerter indicator light is mounted on the control consol, below the
indicator light panel. The Alerter reset push button mounts on the control
consol desktop surface. The Audible Alarm is mounted on the ECC#1 Engine
control panel. ALERTER SYSTEM can be ENABLED through Display Unit
by selecting proper option. When Locomotive Brakes are released, the
Alerter system requests an Acknowledgement from the operator from time to
time, once in 60 seconds. If the Acknowledgement request is not answered
within 60 seconds, the Locomotive control Computer drives a Digital Output
to flash the Alerter light for 17 sec. After 17 sec drive, one more Digital Output
provides an audible sound for 17 sec. If the Alerter request is not
acknowledged, while the Aleter light is flashing or alerter alarm is sounding,
the alarm stops sounding and a penalty Brake is applied for 34 seconds or
until Locomotives speed drops to zero, whichever occurs first. Then the
penalty brake application must be reset before normal operation of train to
continue. One must follow Railway rules and operating practices regarding
use of Alerter Equipment.
Pressing either alerter reset button while the Alerter light is flashing or the
Alerter Alarm is sounding, resets the acknowledgement request timing cycle.
Using the Automatic Brake handle to moderately reduce the brake pipe
pressure also resets the timing cycle. Automatic Brake handle operation also
resets the timing cycle. In addition, movement of the Throttle Handle,
Independent Brake handle or Dy. Brake handle also reset the timing cycle,
as well as pressing the HORN or SAND button.
1.2.3 A E B : Auto Emergency Brake System
While traveling through a terrain with a considerable large Down-Gradient,
speed of the Train needs to be kept under control, so that the AEB system
does not allow to enter in uncontrollable speed zone. Indian Railways has
studied and defined optimum speeds for every section. There is popular
saying that human can do mistakes. There is always chance that a manually
controlled Loco may exceed the section speed limit. Which in turn may cause
major accidents/loss/damage. To avoid this, Indian Railways incorporated a
