Page 28 - 4587

UNIT 5
PLC APPLICATION FOR REDUCED
VOLTAGE-START MOTOR CONTROL

1 Learn the meaning of the following words, word-
combinations and word groups:
Programmable logic controller (PLC), low-voltage protection,
starter, overload, input, in series, in line, continuity,
implementation, timer, instantaneous, hardwired control circuit,
low-voltage protection, interlocking, autotransformer, reduced-
voltage-start motor control circuit, inrush current, locked rotor
current.

2 Read and translate Text 1:
Text 1

Reduced-Voltage-Start Motor Control Circuit

Figure 5.1 shown below illustrates the control circuit and wiring
diagram of a 65% tapped, autotransformer, reduced-voltage-start
motor control circuit. This reduced voltage start minimizes the
inrush current at the start of the motor (locked rotor current) to
42% of that at full speed.
In this example, the timer must be set to 5.3 seconds. Also, the
instantaneous contacts from the timer in lines 2 and 3 must be
trapped.

27