Technical data

March 2009
CA08102001E For more information visit: www.eaton.com
33-103
NEMA Contactors & Starters
33
Freedom
Relays — Thermal Overload
Contents
Description Page
Thermal Overload Relays
Product Description . . . . . . 33-103
Features . . . . . . . . . . . . . . . 33-103
Operation . . . . . . . . . . . . . . 33-103
Technical Information . . . . 33-103
Technical Data . . . . . . . . . . 33-104
Factory Modifications . . . . 33-105
Accessories. . . . . . . . . . . . . 33-105
Replacement Parts . . . . . . . 33-105
Dimensions. . . . . . . . . . . . . 33-106
Product Selection. . . . . . . . 33-107
Heater Pack Selection . . . . 33-107
Product Description
C306 Overload Relays are designed for
use with CE or CN non-reversing and
reversing contactors. Four sizes are
available for overload protection up
to 144A.
Features
■ Selectable Manual or Automatic
Reset operation.
■ Interchangeable Heater Packs
adjustable ±24% to match motor
FLA and calibrated for use with 1.0
and 1.15 service factor motors.
Heater packs for 32A overload relay
will mount in 75A overload relay —
useful in derating applications such
as jogging.
■ Class 10 or 20 heater packs.
■ Load lugs built into relay base.
■ Bimetallic, ambient compensated
operated. Trip free mechanism.
■ Electrically isolated NO-NC contacts
(pull RESET button to test).
(Electrical Ratings see Table 33-158
on Page 33-104).
■ Overload trip indication.
■ Shrouded or fingerproof terminals
to reduce possibility of electrical
shock.
■ Meets UL 508 single-phasing
requirements.
■ UL listed, CSA certified, NEMA
compliance and CE mark.
Operation
C306 Overload Relay Setting
Figure 33-43. FLA Dial Adjustment
For motors having a 1.15 service fac-
tor, rotate the FLA adjustment dial to
correspond to the motor’s FLA rating.
Estimate the dial position when the
motor FLA falls between two letter
values as shown in the example.
For motors having a 1.0 service factor,
rotate the FLA dial one-half position
counterclockwise (CCW).
Figure 33-44. Manual/Automatic Reset
The overload relay is factory set at M
for manual reset operation. For auto-
matic reset operation, turn the reset
adjustment dial to the A position as
shown in the illustration.
Automatic reset is not intended for
two-wire control devices.
Test for Trip Indication
To test overload relay for trip indica-
tion when in manual reset, pull out the
blue reset button. An orange flag will
appear indicating that the device has
tripped. Push reset button in to reset.
Warning — To provide continued pro-
tection against fire or shock hazard,
the complete overload relay must be
replaced if burnout of the heater
element occurs.
Technical Information
General
“Overload relays are provided to pro-
tect motors, motor control apparatus
and motor-branch circuit conductors
against excessive heating due to
motor overloads and failure to start.
This definition does not include:
1) motor circuits over 600V, 2) short
circuits, 3) ground faults and 4) fire
pump control.” (NEC Art. 430-31)
Time Current Characteristics
The time-current characteristics of an
overload relay is an expression of per-
formance which defines its operating
time at various multiples of its current
setting. Tests are run at Underwriters
Laboratories (UL) in accordance with
NEMA Standards and the NEC. UL
requires:
■ When tested at 100 percent of its
current rating, the overload relay
shall trip ultimately.
■ When tested at 200 percent of its
current rating, the overload relay
shall trip in not more than 8
minutes.
■ When tested at 600 percent of the
current rating, the overload relay
shall trip in not more than 10 or 20
seconds, depending on the Class
of the relay.
“Current Rating” is defined as the
minimum current at which the relay
will trip. Per NEC, an overload must
ultimately trip at 125% of FLA current
(heater) setting for a 1.15 service factor
motor and 115% FLA for a 1.0 service
factor motor.
“Current Setting” is defined as the FLA
(Full Load Amperes) of the motor and
thus the overload heater pack setting.
Example: 600% of current rating is
defined as 750% (600 x 1.25) of FLA
current (heater) setting for a 1.15 ser-
vice factor motor. A 10A heater setting
must trip in 20 seconds or less at 75A
motor current for a Class 20 relay.
32A Overload
Cat. No. C306DN3B
1.0
Service
Factor
1.15
Service
Factor
A
BC
D
Example of 12.0 FLA setting for
heater pack number H2011B showing
position for 1.0 or 1.15
service factor motors.
A
M
Example of setting for
manual reset.