Cut Sheet

V10-T17-8 Volume 10—Enclosed Control CA08100012E—November 2012 www.eaton.com
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17.2
Technical Data and Specifications
NEMA Contactors and Starters
C306 Overload Relay Setting
FLA Dial Adjustment
For motors having a 1.15
service factor, 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).
Manual/Automatic Reset
The overload relay is factory
set at M for manual reset
operation. For automatic
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
indication 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 protection against
fire or shock hazard, the
complete overload relay must
be replaced if burnout of the
heater element occurs.
Heater Pack Selection
“Overload relays are provided
to protect 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 performance
that 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
service factor motor. A 10A
heater setting must trip in
20 seconds or less at 75A
motor current for a Class 20
relay.
Class 10 and Class 20 Trip Curves
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
0
1
2
3
4
5
10
20
30
40
50
100
200
300
400
500
1000
2000
3000
4000
5000
10,000
246810
From
Hot Start
From
Cold Start
Multiples of Current Setting
Trip Time
(Seconds)
Class 10 Overload Relay 25°C Open Rating
0
1
2
3
4
5
10
20
30
40
50
100
200
300
400
500
1000
2000
3000
4000
5000
10,000
246810
From
Hot Start
From
Cold Start
Multiples of Current Setting
Trip Time
(Seconds)
Class 20 Overload Relay 25°C Open Rating