Panasonic HL-BD82S Service Manual page 18

HL-BD82S
5.15. Oven Safety Features
5.15.1. Child - safe locking system
All of our ovens are built-in child-safe locking systems. The
future is automatically enabled any time the appliance is con-
nected to the power, any time the switch is turned on and any
time the oven is programmed to run a self-cleaning of the cav-
ity.
The same future it can be is used on the manual mode in the
household where a minor is present to prevent children from
getting in touch with hot parts. The function of this future is
explained in details on the chapter 5.3.5.User lock.
5.15.2. Over heating sensor
All of our ovens are built with a over heating sensor system:
• we have two bi-metal mechanical thermostats for each cav-
ity.
• an electronic sensor [NTC] or [negative temperature coeffi-
cients] mounted on the main power board (see chapter
5.13.Description of Electronic Control for more informa-
tion). The role of the [NTC] is to protect the electronic boards
of an eventually over-heating. (the [NTC] varies with the val-
ues of voltage, only DC, values tabulated at 5.13.Description
of Electronic Control)
An electronic [PTC] or [positive temperature coefficients] probe
mounted on the inside of the cavity who is responsible of the
inside cavity reading of the temperature. (the [PTC] varies with
the resistance — tabulated at chapter...)
5.15.3. Thermostat
All of our ovens are built with two bi-metal mechanical thermo-
stats for each cavity. The thermostats are mounted in contact
with the metal sheet on top of each cavity as shown in the
above pictures.
5.15.4. Double Speed Thermostat
The double speed thermostat is acting in conjunction with the
by-pass resistor and is connected in parallel with it.
In the regular cooking mode when the read temperature at the
surface of the metal sheet in under 158°F (70°C) the power is
flowing trough the resistor and it feeding the cooling fan with a
voltage AC 93V .
If the temperature of 158°F (70°C) is depassed, the thermostat
is closing the circuit and the resistor is by-passed and now we
can read at the poles of the cooling fan motor the full voltage of
installed AC 120V and the RPM of the cooling fan will almost
double.
The reset is automatic when the temperature at the surface of
the metal sheet decreases under the 158°F and the cooling fan
is reducing the RPM at the manufacturer factory set-up.
RPM — rotation per minute
5.15.5. Safety Thermostat
The function of the safety thermostat is to protect the of the
oven from over heating in the event of a malfunction of the cool-
ing fan.
Description: In the regular cooking mode when the read tem-
perature at the surface of the metal sheet in under 260°F
(127°C) the power is energizing the electronics and the heating
elements as well.
In the event that the temperature is rising over the 260°F (127
°C) limit, the thermostat will switch mechanically from off posi-
tion to on position and all of the heating elements will be cut off
from the power.
All of the electronics will be cut off.
The reset is manual when the cooling fan was replaced or the
oven problem was solved and the temperature is in the right
functioning parameters the red button on the top of case of
thermostat must be pressed to reset it (see picture on the pre-
vious page).
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