Product Manual

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Individual Branch Circuit Wiring
All wiring and electrical connections should comply with the National
Electrical Code (NEC) and with local codes and practices. Undersized
wire between the motor and the power source will limit the starting and
load carrying abilities of the motor. The recommended copper wire and
transformer sizes are shown in the following charts.
Single Phase Motors - 230 Volts
WIRE GAGE
A-10 a
GENERAL INFORMATION
GENERAL • Electrical/Connections
SECTION A
General
SECTION B
Design
SECTION C
Catalog
SECTION D
Performance
SECTION E
Connections
SECTION F
Dimensions
SECTION G
Inverter
SECTION H
Index
Efficiency
A motor’s efficiency is a measurement of useful work pro-
duced by the motor versus the energy it consumes (heat and
friction). An 84% efficient motor with a total watt draw of
400W produces 336 watts of useful energy (400 x .84 =
336W). The 64 watts lost (400 - 336 = 64W) becomes heat.
Thermal Protection (Overload)
Athermal protector, automatic or manual, mounted in the end
frame or on a winding, is designed to prevent a motor from
getting too hot, causing possible fire or damage to the motor.
Protectors are generally current and temperature sensitive.
Some motors have no inherent protector, but they should
have protection provided in the overall system’s design for
safety.
Never bypass a protector because of nuisance tripping. This
is generally an indication of some other problem, such as
overloading or lack of proper ventilation.
Never replace nor choose an automatic-reset thermal over-
load protected motor for an application where the driven load
could cause personal injury if the motor should restart unex-
pectedly. Only manual-reset thermal overloads should be
used in such applications.
Basic types of overload protectors include:
Automatic Reset: After the motor cools, this line-
interrupting protector automatically restores power. It
should not be used where unexpected restarting would
be hazardous.
Manual Reset: This line-interrupting protector has an
external button that must be pushed to restore power to
the motor. Use where unexpected restarting would be
hazardous, as on saws, conveyors, compressors and
other machinery.
Resistance Temperature Detectors: Precision-calibrated
resistors are mounted in the motor and are used in con-
junction with an instrument supplied by the customer to
detect high temperatures.
Individual Branch Circuit Wiring
All wiring and electrical connections should comply with the
National Electrical Code (NEC) and with local codes and
practices. Undersized wire between the motor and the power
source will limit the starting and load carrying abilities of the
motor. The recommended copper wire and transformer size
are shown in Chart 1 on this page and Chart 2 on the follow-
ing page.
Adjustable Speed Electric Drives
Reliable, easy-to-use units are available today for controlling
the speed of AC and DC industrial motors. Both types use
solid-state devices for power control.
DC drives are the more straightforward, commonly using sili-
con controlled rectifiers (SCR’s) to convert AC line voltage to
controlled DC voltage, which is then applied to the armature
of a direct current motor. The more voltage applied to the
armature, the faster it will turn. DC drives of this type repre-
sent an excellent value for motors up to approximately 3 HP,
allowing 60:1 speed regulation and full torque even at
reduced speeds.
The most common type of AC drive today begins much the
same way as a DC drive does — by rectifying “pulsing” AC
line voltage to pulse-free DC voltage. However, instead of
outputting the DC voltage, the AC drive must re-introduce
pulses into the output in order to meet the needs of an AC
motor. This is done using solid-state switches, such as insu-
lated gate bipolar transistors (IGBT’s) or gate turn off SCR’s
(GTO’s). The result is a control technique know as pulse
width modulation (PWM), perhaps the most highly regarded
type of AC drive for most industrial applications. Motor speed
varies with the frequency of the pulses introduced into the
output voltage.
Pulse width modulated AC drives offer an extremely wide
speed range, a host of control functions including program-
mable acceleration and deceleration ramps and several pre-
set speeds, excellent energy efficiency and, in many cases,
speed and torque precision equal to or closely approaching
that of a DC system. Perhaps the major reason for their
growing popularity, however, is their ability to work with the
wide range of AC induction motors available for industry, usu-
ally at a price competitive with that of a DC drive package.
(Refer to Section G for Inverter capabilities of LEESON
Chart 1Single Phase Motors – 230 Volts