Infinite Heat Controls; Thermal Limiter Switch - GE JB960 B Technical Service Manual

INFINITE HEAT CONTROLS

Infinite heat controls are used to regulate the
wattage of the surface units. The infinite heat
control is essentially a timing device, and its on-
off time is not related to any temperature sens-
ing element at the surface unit (such as the sen-
sor head of an automatic surface unit).
The controls have two detent positions - OFF
and HIGH. Between the these two positions is
an infinite range of heat selections. At the high
detent setting, the surface unit is energized con-
tinuously.
There are two basic types of infinite heat con-
trols used on the new Spectra
One is a Voltage Sensitive control and the other
is a Current Sensitive control.
Internally both controls (voltage sensitive and
current sensitive) contain a bi-metal control which
regulates the switch ON-OFF time. The bi-metal
has a heater wrapped around it which supplies
heat to the bi-metal, opening and closing the
control cycling contacts. As you will note from
the illustrations to the right, the heater is only
energized when the cycling contacts are
closed.

THERMAL LIMITER SWITCH

Attached to each surface element is a thermal
limit switch. This switch serves two purposes.
1. Controls cooktop surface "HOT" light op-
eration.
2. Removes power to the surface element, in
the event that the cooktop glass directly
above the element exceeds 1031° F.
When the temperature of the cooktop glass,
above the heating element, reaches 150° F., a
set of contacts in the thermal switch will close
and provide power to the HOT light. The hot
light will remain on until the glass surface above
the element cools below 150° F. The HOT light
is mounted to the control panel and is located
just below each control knob (see Illustration to
the right).
The second set of contacts in the thermal limit
switch remove power to the element in the event
the cooktop glass above the element exceeds
1031° F. If this condition should ever occur the
contacts in the thermal limit switch will open and
remove power to the element. Once the cooktop
glass cools below 1031° F., the contacts in the
thermal limit switch will close and the element
will resume operation.
series of ranges.
™
– 21 –
PILOT
N
P
L1
H1
L1
H2
L2
< 1 Ω
L2
L2
N
H2
5 4
P
10.45 KΩ
CYCLING
CONTACT
2 3
H1
GRND
L2
H2
15.59K Ω
L1
H1
P
N
PILOT
THERMAL LIMITER
SWITCH
FRONT BRIDGE
BURNER BURNER
OFF
FRONT
HOT LIGHT LOCATIONS
H1
P
H2
RR
SURFACE
UNIT
L1
L2
CURRENT
SENSITIVE
VOLTAGE
SENSITIVE
LR
SURFACE P L1 L2
UNIT
H1
VOLTAGE SENSITIVE
SURFACE
ELEMENT
Therm.
Limit Sw.
L2
Hot Light
THERMAL LIMITER
SCHEMATIC
HOT
REAR
TOP
H2