HP (Hewlett-Packard) CF081A#BGJ Benutzerhandbuch

To protect the fuser from excessive temperatures, the product has four layers of protective functions. If

one function fails, the subsequent functions should detect the problem.

●

DC controller: When a thermistor or thermopile detects a temperature above a certain threshold,

the DC controller interrupts power to the specific heater. Following are the thresholds for each

component:

◦

TH1: 230° C (446° F) or higher

◦

TH2: 285° C (545° F) or higher

◦

TH3: 285° C (545° F) or higher

●

Fuser heater safety circuit: If the DC controller fails to interrupt the power to the heaters at the

prescribed temperatures, the fuser heater safety circuit deactivates the triac-drive circuit and

releases the relay, which causes the heaters to stop at slightly higher temperature thresholds. 

◦

TH2: 290° C (554° F) or higher

◦

TH3: 290° C (554° F) or higher

●

Current detection protection circuit: If current flowing in each triac exceeds a specific value,

the current detection protection circuit deactivates the triac-drive circuit and releases the relay,

which interrupts the power supply to the heaters.

●

Thermoswitch: If the temperature in the heaters is abnormally high, and the temperature in the

thermoswitches exceeds a specified value, the contact to the thermoswitch breaks. Breaking this

contact deactivates the triac-drive circuit and releases the relay, which interrupts the power supply

to the heaters. Following are the thresholds for each thermoswitch:

◦

TP1: 270° C (518° F) or higher

When the thermoswitches reach this temperature, the temperature on the fuser rollers is about

320° C (608° F).

ENWW

Engine control system

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