JPH0357180A - Temperature regulating device equipped with heater failure alarm - Google Patents

Abstract

PURPOSE:To operate correctly a heater temperature control system of a phase control type and secure setting an alarm action point by controlling a heater power controller based on comparison of a value from a temperature sensor with a value from a temperature setting part, and composing a temperature regulating device to give an alarm when a value of ratio of a heater current to a heater voltage is other than a set value. CONSTITUTION:A temperature regulation function part for a heater A controls the temperature of the heater A by comparing a value from a temperature sensor 2 with a value from a temperature setting part 6 and controlling a heater current controller 1 for controlling a heater power. A failure alarm function part for the heater A is composed of a load setting part 12 for setting the ratio of a heater current to a heater voltage under normal operation, and an alarm setting part 13 for setting a tolerable range of change rates of the ratio of the heater current to the heater voltage under monitoring, so as alarm is given when the ratio of the heater current to the heater voltage is other then set values.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention is useful for controlling the temperature of industrial electric furnaces and drying, as well as controlling the temperature of heaters. This invention relates to a temperature control system with a heater failure alarm that detects failures such as Ii wires or short circuits and issues an alarm.

<Prior Art> Conventionally, heater temperature controllers that control the temperature of electric furnaces and drying ovens, and failure alarms that detect heater failure and issue alarms have been provided as independent devices. , li!, which organically combines a heater temperature Wi controller and a failure alarm. II is not yet available. Therefore, as a matter of course, the failure alarm will indicate the heater temperature a:
It was not possible to detect a failure in the system, including the latch.

Moreover, in the conventional heater failure alarm system, the heater temperature $11tllll method uses a thyristor to control the phase IIIm
In the case of this method, there was a problem that it could not be used because the current value changed in principle.

<Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned problems in the prior art. It can also detect failures, and operates accurately even when the heater temperature control method is the phase υ111] method.
Moreover, it is an object of the present invention to provide a temperature control device with a heater failure alarm, which allows setting of an alarm operating point easily and reliably regardless of individual differences.

<Means for Solving the Problems> The temperature control device with heater failure alarm of the present invention that achieves the above object comprises a temperature sensor, an analog multiplexer that alternately takes in signals of heater current and heater voltage as input, and the multiplexer. An AD converter that converts the output signal of the breaker into a digital signal, a temperature setting section that sets the heater temperature, a load setting section that sets the ratio of heater current and heater voltage during normal operation, and heater current during monitoring. and a temperature control output section that outputs a control signal 1 to the heater electric controller, and a failure alarm output section that operates the w+FA device. The controller is configured to control the heater power regulator by comparing the value from the melon sensor and the value of the temperature setting unit, and when the value of the ratio of heater current to heater voltage deviates from the set value. This system is characterized by the fact that it issues an alarm.

Example Embodiments of the present invention will be described below based on the drawings.

The temperature adjustment function section of the controller A includes an analog multiplexer 3 that takes in the output signal of the temperature sensor 2 as an input, and an AD conversion that converts the output signal of the multiplexer 3 into a digital signal via a rectifier circuit 4. 5, a temperature setting section 6 for setting the temperature of the heater ~A, and a heater power control II
It is composed of a lagoon υ1 control output section 7 which outputs a heater power aIIIt11I signal to the temperature sensor 1, and controls the heater power controller 1 by comparing the value from the temperature sensor 2 and the value from the temperature setting section 6. The temperature of the heater A is controlled by controlling the heater power.

The flaw setting section 6 and the temperature control output section 7 are incorporated into the one-chip microcomputer B, and processing such as comparing the value from the temperature sensor 2 and the value from the knitting setting section 6 is performed by a program. The temperature is set using the numerical keys of the operation keys 8 while being monitored on the display 9, and is set using the temperature setting key 8a.

In addition, the failure alarm function section of heater 8 is configured to transmit the heater current and heater voltage to the instrument current transformer 10 and the instrument transformer 11.
The analog multiplexer 3 receives the output signal alternately as an input via the rectifier circuit 4.
an AD converter 5 that converts the signal into a digital signal via a load setting unit 12 that sets the ratio of the heater Ti current to the heater voltage during normal operation, and an allowable rate of change of the ratio of the heater current to the heater voltage during monitoring. An alarm setting section 13 that sets a range, and a failure alarm output section 14 that operates an alarm (not shown).
It is configured to issue an alarm when the value of the ratio of heater current to heater voltage deviates from the set value. That is, the heater current and heater voltage that are alternately taken in as input via the analog multiplexer 3 are automatically taken in by the load setting section 12 by operating the load setting key 8b of the operation key 8. The ratio of heater current (I6) to heater voltage (Vs) at that time (heater normal vf) (
Is/Vs) is stored in the memory in the one-chip microcomputer B, and the load is set. At this time, if a non-permanent memory backed up by a battery is used as the memory, if the -i load setting is performed, there is no need to set the load again. Then, using the numerical keys of operation key 8,
While monitoring on the display 9, the heater current (
Enter the permissible range of the rate of change of the ratio (IX/VX) of lx) and heater voltage CVX > as a percentage, store the value in the memory in one-chip microcomputer B with the alarm setting level 8C, and set the heater current and When the value of the heater voltage ratio deviates from the set value, a signal is output from the failure alarm output section 14 to issue a heater failure alarm. Expressing this in a formula, the disconnection alarm t11 setting value set in the alarm setting section 13 is A.

Short M! When the alarm setting value is As, if 1s xA6 > 1x, I5 V6 (V5), it is judged as normal, (s XA5 < l If this happens, it is determined that there is a failure in the RFi line, and an alarm is output. Note that these calculations and other processing are performed by a program in the one-chip micron B.

At this time, if the heater voltage is zero, the calculation becomes impossible, so the program of the one-chip microcomputer B is designed to prevent malfunctions by taking care not to perform an alarm operation when the heater voltage approaches zero.

Also, if the temperature control method of heater A is an on-off control method and the number of heater wires is small, the current change due to a failure of heater A will be larger than the beginning of the change in power supply voltage, so the ratio of heater current to heater voltage will change. Although it is possible to detect a failure with both f, the current value becomes zero when the heater is OFF, so the temperature control yj is connected to the heater voltage input terminal.
It is necessary to input an off signal from AA+ to stop the alarm operation.

In addition, in the system (vorticity control system) that includes the heater power control tips for heater A, the heater power always fluctuates depending on the leakage state of heater A, and sometimes the output is on and sometimes the output is off. , heater power controller 1
If the heater voltage is pillow volts (no voltage) even though the heater outputs an output on signal, or if the heater power I
If the heater voltage is not zero volts when the l1 controller 1 is giving an output-off signal, the ratio of the heater current and heater voltage taken in as input will deviate from the set value, so an alarm will be output.

<Effects of the Invention> Since the temperature control device with a heater failure alarm according to the present invention is configured in this manner, it is possible to control the temperature of the heater by controlling the heater power limiter, and at the same time, the temperature of the heater can be controlled. It is also possible to detect system failures, including the III control system.

Moreover, since most parts can be shared between the temperature control function section and the failure alarm function section, cost performance is significantly higher than when a conventional temperature controller and failure alarm are used together. I can do it.

Furthermore, in the fault alarm function, the normal state of the heater (ratio of heater current to heater voltage) can be stored in the load setting section and alarm settings can be made as a percentage, which eliminates the need to measure the heater current. Instead, each setting can be digitally set while being monitored on a display, so it can be done simply and reliably, regardless of individual differences.

In addition, heater failure is detected based on the ratio of the heater 7B flow and heater voltage, so if the heater power supply voltage fluctuates or the heater temperature control method is a phase control method using a thyristor, Applying the heater to the heater can be operated quickly and accurately even with heaters whose withstand voltage changes, and at the same time, for example, in a heater with 10 heater wires, if one of them breaks, the ratio of heater current to heater voltage will change. Although the change is 10%, it can be reliably detected by setting the alarm settings accordingly.

Therefore, the intended purpose can be achieved.

[Brief explanation of drawings]

The drawing is a circuit diagram showing an embodiment of the present invention. In the diagram A: Heater B: One-chip microcomputer 1: Heater power control I2D device 2: Temperature sensor 3: Analog multiplexer 4: Rectifier circuit 5: AD converter 6° temperature setting section 7: Temperature υ1611 output section 8: Operation key
9: Display

Claims (1)

[Claims] an analog multiplexer that alternately takes in signals of the temperature sensor, heater current, and heater voltage as input; an AD converter that converts the output signal of the multiplexer into a digital signal; and a temperature setting unit that sets the temperature of the heater; A load setting section that sets the ratio of heater current and heater voltage during normal operation, an alarm setting section that sets the permissible range of change rate of the ratio of heater current and heater voltage during monitoring, and a control signal to the heater power controller. a temperature control output section that outputs;
and a failure alarm output section that operates an alarm, and controls the heater power controller by comparing the value from the temperature sensor and the value of the temperature setting section, and also controls the ratio of heater current to heater voltage. A temperature control device with a heater failure alarm, characterized in that an alarm is issued when a value deviates from a set value.