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Pre-Installation
INSTALLATION
2-5
Description
Sensing the line voltage provides important
information for diagnostics and motor protection.
The features include the following:
Phase Rotation Protection:
Inhibits starting of the motor unless rotation is
A-B-C.
Phase Loss Protection:
Trips starter off line if one or more phases are
lost.
Under-Voltage Protection:
Trips starter off line if line voltage drops
below 75% of nominal rating.
The Easy-Start ES has a built-in
adjustable
ramp
which can be used in either voltage mode
or current mode. It also has an adjustable initial
step which represents initial voltage or initial
current depending on the position of the
voltage/current ramp DIP switch ÒDS3-1.Ó The
ramp and initial step functions are in the circuit
only in the start mode.
The ramp and voltage/current signals are fed into
a main
amplifier
. This amplifier is biased by an
adjustment marked
MIN
. This adjustment is used
to set the minimum motor voltage at no load. It is
factory set to about 50% of nominal line voltage.
The amplifier also has a stability adjustment
which can be used to handle difficult motor load
applications. It is marked
STAB
and is factory
set to approximately midpoint.
A
digital trigger
is used on the SCR gates. It
gives near perfect balance of motor voltage
between phases. Its hard firing and fast rise-time
gate pulses insure positive firing of the SCRÕs. Its
wide range insures motor voltage control from
zero to full line voltage with power factors from
0.1 to 1.0.
The
current unbalance
circuit senses each line
current and the signals are sent to comparators.
The circuit senses when the line currents are
unbalanced and trips the starter off line whenever
the unbalance is greater than 20% from the
average. This feature is useful in diagnostics and
will be covered more in the troubleshooting
section of this manual.
The
lockout
is an input to the digital trigger. It is
at a logic ÒhighÓ during normal operation. It is
forced to a logic ÒlowÓ by any one of the
protective or alarm functions. In this low state the
gates of the digital trigger are inhibited or Òlocked
outÓ to prevent firing of the SCRÕs.
Easy-Start ES Instruction Manual
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