North American TwinBed® II 8752C Overtemperature Switch
Bulletin 8752C
The 8752 TwinBed Overtemperature Switches are single or dual input
devices that detect burner bed over temperature. They are normally
connected to a control panel, where they can initiate burner shutdown,
interlocking and/or annunciation.
These switches accept one or two type K thermocouple inputs. On bed
overtemperature, a relay contact opens and an LED lights, indicating
which bed is overtemperature. Once the relay has opened, it will not
close until any connected thermocouples are below the overtempera-
ture limit and either the RESET button is pressed or power to the unit is
cycled.
The 8752 has easily accessed controls, with externally visible LEDs
and a front cover reset switch. A green LED indicates normal operation.
During an overtemperature situation, red LEDs indicate which channel
is over temperature. Red LEDs indicate an open thermocouple on either
channel.
The switch is designated as the 8752C and is available as a single input or dual input, for either panel or fi eld mounting.The remote version is plugged
into a panel mount edge connector (provided with the unit).
The fi eld mount version consists of a NEMA 12 type enclosure with a ventilated outer box that includes provisions for supplying cooling air. Terminal
strips are provided for the power and thermocouple connections. The thermocouple terminals are accessible from outside the enclosure for bed tem-
perature measurements using a meter.
The 8752 options and part numbers are:
8752C-SF-0250: Single input fi eld mount
8752C-SF-0750: Single input fi eld mount
8752C-DF-0250: Dual input fi eld mount
8752C-DF-0750: Dual input fi eld mount
8752C-DB-0250: Panel mount with edge connector
8752C-DB-0750: Panel mount with edge connector
8752C-SF-0600: Single input fi eld mount
8752C-SF-1000: Single input fi eld mount
8752C-DF-0600: Dual input fi eld mount
8752C-DF-1000: Dual input fi eld mount
8752C-DB-0600: Panel mount with edge connector
8752C-DB-1000: Panel mount with edge connector
Note:
The "-0750" designates the preset actuation temperature of 750 F; "-1000" designates 1000 F actuator temperature.
The "-0250" designates the preset actuation temperature of 250 F; "-600" designates 600 F actuator temperature.
The "-0750" and "-1000" range are bed overtemperature ranges.
The "-0250" and "-0600" range are exhaust blower ranges.
SPECIFICATIONS
Power Requirements:
102-132 V ac, 50-60 Hz, 6 VA max.
Ambient Temperature Rating:
8752C-DB: 32-160 F (0-70 C).
Others: 32-180 F (0-80 C). Cooling air is required at ambients over 160 F.
Cooling Air (-DF and -SF only):
140 scfh required. The supplied fi tting will
limit the air fl ow to 140 scfh at 12 osi line pressure. Cooling air temperature
must be less than 130 F.
Actuation Temperature:
750 F or 1000 F.
Output:
Normally open electro-mechanical relay contact
(isolated).
Relay Contact Rating:
0.5 A resistive at 120 V ac.
Reset Mechanism:
Pushbutton switch or power cycling.
Bed Overtemperature and Open Thermocouple Indication:
Red LED.
Normal Operation Indicator:
Green LED.
Temperature Sensing Device:
Type K Thermocouple (grounded or un-
grounded). North American recommends the 8752T. See Maintenance Sheet
8752T for information.
Field Mount
Panel Mount
Combustion
