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DEVICE SELECTION
Articles 240 and 430 of the NEC contain the rules for
selecting fuses, circuit breakers and overload relays by
type and by voltage and ampere rating. Follow these
rules for feeder circuits, and the instructions attached to
the inside of the left-most vertical wireway door, for mo-
tor branch circuits. Select and install overload relay cur-
rent elements (heaters) based on the motor service fac-
tor and full-load current. Ambient compensated over-
load relays are used in motor control centers (MCC's) to
offset the temperature gradient which occurs from top to
bottom in a loaded vertical section.
HEATERS MUST BE INSTALLED IN THE STARTER
OVERLOAD RELAY ASSEMBLIES BEFORE THE
STARTER IS ENERGIZED.
C306 THERMAL OVERLOAD RELAYS (Fig. 24)
C306 Overload Relays are provided on Freedom Start-
ers. Four sizes are available for overload protection up
to 11 4 amperes. Features include:
•
Selectable Manual or Automatic Reset operation.
lnterchangeble Heater Packs ajustable ±24% to
•
match motor FLA and calibrated for use with 1.0 and
1.15 service factor motors.
Heater packs for 32 ampere overload relay will mount
in 75 ampere overload relay-useful in derating appli-
cations such as jogging.
•
Class 1 0 or 20 heater packs. (Fig. 24) Use Class 1
0 heaters with fusible or thermal magnetic breaker
disconnects only.
•
Bimetallic, ambient compensated operated. Trip free
mechanism.
•
Electrically isolated NO-NC contacts (pull RESET
button to test).
•
Overload trip indication.
•
Single phase protection.
•
UL listed, CSA certified and NEMA compliance.
Fig. 23 Overload Relay Settings
PART 6
OVERCURRENT PROTECTION DEVICES
- Page 15 -
Fig.24 C306 Thermal Overload Relay and Heater Pack.
C306 OVERLOAD RELAY SETTING
FLA DIAL ADJUSTMENT- For motors having a 1.15
service factor, rotate the FLA adjustment dial to corre-
spond to the motor's FLA rating. Estimate the dial posi-
tion when the motor FLA falls between two letter values
as shown in Fig. 23.
For motors having a 1.0 service factor, rotate the FLA
dial one-half postion counterclockwise (CCW).
MANUAL/ AUTOMATIC RESET -The overload relay is
factory set "M" for manual reset operation as shown in
Fig. 23. For automatic reset operation, turn the reset
adjustment dial to the "A" position.
Automatic reset is not intended to two-wire 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.
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.
I.B. 8926-1
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