Cutler Hammer, Div of Eaton Corp S752 Features and Benefits

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 deceler-
ation 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 enhance-
ments 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 Cutler-
Hammer 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, wye-
delta 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 three-
phase 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 electromechani-
cal starters.

The starter uses Silicon Controlled
Rectifiers (SCRs) to ramp the voltage
to the motor, providing smooth accel-
eration and deceleration of the load.
After the motor is started, the internal
run bypass contactor closes, resulting
in the motor running directly across-
the-line. Internal run bypass signifi-
cantly 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 coast-
to-stop time.

The built-in solid-state overload pro-
tects the motor from overload condi-
tions with sophisticated algorithms
that model true motor heating, result-
ing in better motor protection and
fewer nuisance trips. Advanced pro-
tective 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 break-
ing the motor load in failed SCR condi-
tions. 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 non­bypass soft starters. Less heat mini­mizes 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 measure­ment and trip settings.
Sophisticated algorithms solve a
series of differential equations that

model true motor heating and cool­ing, resulting in superior motor over­load 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 accelera­tion 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 assem­bly 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.

February 2007

Reduced Voltage Motor Starters
Solid-State Starters

Type S752, Intelligent Technologies (IT.) Soft Starters

39-15

■ Wide range of overload FLA settings

(31 – 100% of rated current) and
selectable trip class (10, 20, 30)
allows for wide application range
while offering users the flexibility to
fine tune the starter to match their
specific application requirements.

■ Soft acceleration and deceleration

reduces wear on belts, gears,
chains, clutches, shafts and
bearings.

■ Minimizes the peak inrush current’s

stress on the power system.

■ Minimizes peak starting torque to

diminish mechanical system wear
and damage.

■ 24V DC control module enhances

personnel and equipment safety.

■ Removable, lockable control termi-

nal block reduces maintenance
replacement costs. Also provides
the opportunity for OEMs to reduce
assembly and test costs by utilizing
pre-assembled wire harnesses.

Protective Features

Motor Overload

The S752 includes electronic overload

protection as standard. The overload

meets applicable requirements for a

motor overload protective device.

The overload protects the motor from

over heat conditions with the use of

sophisticated algorithms that model

true motor heating resulting in supe-

rior motor protection and fewer

nuisance trips.

The S752 calculates a thermal memory

value. A 100% value represents the

maximum safe temperature of the

motor. When the thermal memory

value reaches 100%, an overload trip

will occur removing power to the

motor. Upon trip, the S752 stores the

calculated motor heating value and

will not allow a motor re-start until the

motor has sufficiently cooled. This fea-

ture ensures the motor will not be

damaged by repeated overload trip

and re-start cycles.

The trip current is adjusted to match

the specific application requirements

by adjusting the overload FLA setting.

The FLA adjustment includes a 3 to 1

adjustment range. The overload trip

class is selectable for class 10, 20 and

30. The overload is ambient tempera-

ture compensated, meaning its trip

characteristics will not vary with

changes in ambient temperature.

Short Circuit

The use of a short circuit protective
device in coordination with the S752 is
required in branch motor circuits by
most electrical codes. Short circuit
coordination ratings with both Cutler­Hammer molded case circuit breakers
and fuses are available providing
customers with design flexibility. The
S752 has short circuit coordination
ratings as an open component, an
enclosed starter, and in a Motor
Control Center.

Pole Over Temperature

High ambient temperatures, extended
ramp times and high duty cycle condi­tions may cause the S752 power pole
conductors to reach a temperature that
exceeds their thermal rating. The S752
is equipped with sensors that monitor
the temperature of the power poles.
Over temperature protection exists if
the device’s thermal capacity is
exceeded. The soft starter will trip in
over temperature conditions, prevent­ing device failure.

Phase Loss

Loss of a phase can cause a significant
increase in current drawn in the
remaining two phases. Phase loss can
lead to motor damage before an even­tual overload trip occurs. Phase loss is
typically an indication of a failure in
the electrical distribution system. The
S752 can detect a phase loss and after
10 seconds a phase loss trip will occur.
The phase loss protection can be
enabled or disabled.

Phase Imbalance

Phase current or voltage imbalance
can cause a significant increase in the
current drawn in the other phases.
Phase imbalance can lead to motor
damage before an eventual overload
trip. Phase loss is typically an indica­tion of a failure in the electrical distri­bution system or the motor. A phase
current imbalance trip will occur if one
or two of the line currents are 50% or
less of the remaining line(s) for longer
than 10 seconds. The phase imbalance
protection can be enabled or disabled.

Reset Mode

The S752 can be set up for automatic
or manual reset on trip. The manual
reset mode requires the operator to
physically press the RESET button
located on the soft starter. The auto­matic reset mode allows the soft
starter to be automatically reset as
soon as the trip condition is no longer
present. With the automatic reset
mode, after the fault is no longer
present, the motor will be restarted as
soon as a valid start signal is present.
The overload can be reset through the
communications network. The over­load can also be electrically reset by
energizing a 24V DC control input on
the control terminal block.

Bypass Dropout

The S752 can detect if the bypass
contactor fails to close after the
ramp start or opens while the motor
is running. The S752 will trip on a
bypass dropout fault if either of
these conditions occur.

Diagnostic Features

The S752 has an easy to read LED that
displays the device status as well as
identifying the condition that caused a
fault. The fault display is a useful tool
in system troubleshooting. The follow­ing fault cross-reference is listed on
the overload cover of the device to
facilitate fault identification:

Table 39-13. S752 Diagnostic Features

LED
Display
Code

0 Ready To Start

1 Line Phase Reversal

2 Phase Loss Fault

3 Phase Imbalance Fault

4 SCR Over Temperature Fault

5 Overload Trip Fault

6 Test Trip Fault

7 Bypass Dropout Fault

8 Overload Communications Fault

9 Temperature Sensor Fault

Device Status
or Fault

Communication Capabilities

Communications are enabled with
the S752 soft starter with the addition
of a SNAP (Starter Network Adapter
Product). The SNAP allows for
network control and monitoring of
system parameters. See
more information on SNAPs.

Tab 50

for

39

CA08102001E For more information visit: www.eaton.com