Cutler Hammer, Div of Eaton Corp S752 General Product Line Information

Reduced Voltage Motor Starters
Solid-State Starters

Type S752, Intelligent Technologies (IT.) Soft Starters

February 2007

39

Contents

Description Page

Type S752, Intelligent

Technologies (IT.) Soft Starters

Product Description. . . . . . . 39-14

Application Description. . . . 39-14

Features and Benefits . . . . . 39-14

Operation . . . . . . . . . . . . . . 39-16

Catalog Number

Selection . . . . . . . . . . . . . . 39-16

Product Selection . . . . . . . . 39-17

Accessories . . . . . . . . . . . . . 39-19

Renewal Parts . . . . . . . . . . . 39-19

Standards and

Certifications . . . . . . . . . . . 39-19

Instructional Leaflets . . . . . . 39-19

Technical Data and

Specifications . . . . . . . . . . 39-20

Dimensions . . . . . . . . . . . . . 39-21

S752

Product Description

Eaton’s Cutler-Hammer® Intelligent
Technologies (IT.) S752 Line of
Reduced Voltage Soft Starters is very
compact, multi-functional, easy to
install and easy to program. Designed
to control the acceleration and deceler­ation of three-phase motors, the
device is available in configurations to
be applied either in the line of the
motor, or in the delta windings of the
motor. The in-line device is available
for current ranges from 0.25 to 50
amps. The inside-the-delta device is
available for current ranges from 0.44
to 78 amps.

The S752 is a redesign of the popular
S751 soft starter. Design enhance­ments include an increased current
rating, short circuit coordination
ratings with breakers and fuses, and
inside-the-delta control. The S752
has replaced the S751 in the Cutler­Hammer product offering.

The S752 is designed to be a complete
package combining the SCRs, bypass
contactor and overload in one, very
compact device. The S752 is available
as a component for panel mounting, in
Motor Control Centers or in Enclosed
Control (NEMA Type 1, 3R, 4, 4X, 7/9
and 12).

Application Description

The S752 combines the soft starter
overload, bypass contactor into one
device for fast and easy installation.
With its small size, it can easily fit in
place of existing soft starters, wye­delta starters or across-the-line NEMA
and IEC starters. This feature allows
easy upgrades to existing systems.

The in-line version is designed for use
with three-phase motors in a delta
(three-lead) configuration. The product
is designed to be wired in the three­phase line feeding the three motor
input leads as is done for normal
across-the-line starting.

The inside-the-delta version is to be
used on 6-lead or 12-lead wye-delta
motors. The device is wired into the
windings of the motor. A reduced
voltage start is achieved without the
need to reconnect the motor in wye
and delta configurations. The S752
offers enhanced performance over
traditional wye-delta electromechani­cal starters.

The starter uses Silicon Controlled
Rectifiers (SCRs) to ramp the voltage
to the motor, providing smooth accel­eration and deceleration of the load.
After the motor is started, the internal
run bypass contactor closes, resulting
in the motor running directly across­the-line. Internal run bypass signifi­cantly reduces the heat generated
as compared to non-bypass starters.
The soft stop option allows for a ramp
stop time that is longer than the coast­to-stop time.

The built-in solid-state overload pro­tects the motor from overload condi­tions with sophisticated algorithms
that model true motor heating, result­ing in better motor protection and
fewer nuisance trips. Advanced pro­tective and diagnostic features reduce
downtime.

The S752 was designed with safety in
mind. The device features a fully
motor-rated run bypass contactor. The
bypass contactor is capable of break­ing the motor load in failed SCR condi­tions. Short circuit protection ratings
are offered with both circuit breakers
and fuses. Safety is enhanced with the
use of green materials, 24V DC control
and finger safe IP20 terminals.

Features and Benefits

■ Run bypass significantly reduces the

heat generated as compared to non-
bypass soft starters. Less heat mini-
mizes enclosure size and cooling
requirements and maximizes the life
of all devices in the enclosure.

■ Run bypass mode greatly reduces

internal heating created by the
power dissipation across the SCRs.
The bypass contactor directly
connects the motor to the line
and improves system efficiency
by reducing internal power losses.

■ Solid-state overload protection pro-

vides accurate current measure-
ment and trip settings.
Sophisticated algorithms solve a
series of differential equations that

model true motor heating and cool-
ing, resulting in superior motor over-
load protection while minimizing
nuisance trips. Advanced selectable
protective features safeguard the
motor and system against a variety

of system faults.

■ Six SCRs control all three motor

phases providing smooth accelera-
tion and deceleration performance.

■ Easy to read LED displays device

status and provides fault indication.

■

Internal run bypass contactors and
overload protection eliminate the
need for additional devices,
thereby reducing enclosure sizes,
minimizing installation and wiring
time and reducing overall assem-
bly size and cost.

■ Variable ramp times and torque

control settings provide unlimited
starting configurations, allowing for
maximum application flexibility.

■ Soft stop control suits applications

where an abrupt stop of the load is
not acceptable.