JPS6037676Y2 - Anomaly detection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an abnormality detection device that detects an abnormality in an air conditioner or the like and issues an alarm.

If there is a power outage or overload in an air conditioner, etc., and abnormalities in temperature, pressure, or current are detected,
A signal is output from the protective equipment, and the signal is applied to a central processing unit (CPU) of a microcomputer, etc., where an alarm is issued.

By the way, if the abnormality detection device is composed of a relay or the like, the combined voltage level and operation speed match the abnormality input signal, so the circuit can be configured without any particular problem, but if the abnormality detection device is - In the case of an electronic circuit such as a MOS, special consideration must be given to signal reception because the voltage level used and the operating speed are significantly different.

This invention was devised in view of this situation, and its first
The purpose of this invention is to provide an abnormality detection device that can eliminate mechanical moving parts and improve reliability.

A second object of the present invention is to provide an abnormality detection device that can store alarm conditions using a simple circuit.

An embodiment of the present invention will be described below with reference to the drawings.

E is an AC power supply, S□ is an alarm contact that is on when the device is in normal operation, Dl is a protection diode, D2 is a light emitting diode, Ro is a protection resistor, and Q□ is a photo sensor along with the above light emitting diode D2. A phototransistor forming a coupler, R1 is an emitter resistance of the phototransistor Q1, R2 is a resistance that forms a time constant circuit together with a capacitor C, D3 is a backflow prevention diode, R3 is a discharge resistance, R1 is a resistance A, and A dividing resistor that divides the voltage, S
2 is a switch that is turned off when the load such as an air conditioner is in operation and turned on when it is stopped; R6 is a dividing resistor that divides the voltage together with the resistor R5; D4 is a backflow prevention resistor; Q2. Q3 is an inverter, and Q and Q are output terminals, which are connected to the CPU.

Next, to explain the operation based on the above circuit, when the load is in normal operation, the alarm contact S□ is in the closed state, so the power supply E connects the contact S1, the resistor R8, and the light emitting diode D.
2 is energized.

Therefore, since the light emitting diode D2 is turned on in the positive section of the power supply E, the phototransistor Q1 is turned on, and a voltage close to Vcc is generated across the resistor B2.

This voltage flows to the capacitor C via the resistor R2 and the diode D3, and charging begins.

Note that here, since the resistances R2 and R3 satisfy R2<<R3, most of the charging current flows through the resistance R2.

After a time constant due to the time constant circuit of resistor R2 and capacitor C, the output of inverter Q2 becomes low level, the output of inverter Q3 becomes bilevel, an output is output from output terminal Q, and this is input to the CPU. Ru.

Further, when the phototransistor Q1 is turned off, the charge in the capacitor C is discharged via the resistors R3 and R1.

In this case, the resistor R3 and the capacitor C
Determine the constant of

Here, when switch S2 is turned on by a stop command and the circuit power is turned on, the output of inverter Q2 becomes low level and the output of inverter Q becomes bilevel, and is output to output terminal Q, regardless of the presence or absence of power supply E. will appear and there will be no alarm.

Since this means that the load is in a stopped state, no abnormality is detected.

Furthermore, if the circuit power is turned on with the switch S2 in the OFF state according to the operation command, it takes time to charge the capacitor C, and a voltage does not appear immediately at the input of the inverter Q2.

On the other hand, since the phototransistor Q1 is immediately turned on, the voltage across the resistor R1 reaches the voltage Vcc. Therefore, due to the time difference between the two, the input of the inverter Q2 is determined to be low level, and the output of the inverter Q2 is determined to be a bilevel. Then, it is sent out from the output terminal Q as an alarm signal.

This is to prevent malfunctions when the circuit power is turned on with the operation command still intact.

By the way, as mentioned above, when capacitor C is charged, the output of inverter Q2 is at low level, the output of inverter Q3 is at bilevel, and an output without alarm is being sent from output terminal Q, there is an abnormality in the load. When the alarm contact S1 is opened, the light emitting diode D2 is turned off and the phototransistor Q1 is turned off.
The charge in the capacitor C is discharged through the resistor 129 R1, and the voltage across it becomes 1/2 VCC or less.

In this state, the input of inverter Q2 detects a low level, and the output of inverter Q becomes a low level, so the resistor R
5. Drop the input of inverter Q2 to ground level with the circuit of diode D4.

This is to prevent the previous alarm memory from being erased by charging the capacitor C when the power supply E is restored and the phototransistor Q□ is turned on.

That is, the voltage of capacitor C is divided by resistor R8R5, and the value of the dividing resistor is determined so that it does not exceed 112Vcc.

Therefore, once an alarm occurs and is stored in memory, the alarm memory will not be erased unless the circuit power is turned off or the memory is reset by the method described below.

Another method for resetting the memory is that the alarm output is enabled when the switch S2 is in the OFF state during operation, so when the switch S2 is stopped for resetting, the Vc
c is applied through the path of resistors R6, R5 and diode D.

At this time, by determining the division ratio of the resistors R5 and R6 so that the input of the inverter Q2 becomes 1/2 VCC or more, it becomes possible to reset the memory by turning on the switch S.

As mentioned above, the present invention does not use mechanical moving parts such as relays, so reliability can be improved and alarms can be easily stored in the memory by the circuit.Moreover, the charging circuit is configured so that the output of the phototransistor is halved. Even if the wave is a rectified wave, it can be stabilized as a DC level and has the effect of being able to detect abnormalities including disconnections.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of the abnormality detection device according to the present invention. S□...Alarm contact, D□...Protective resistor, D2゜Ql...Light emitting diode and phototransistor forming the photocoupler, R1 to R3?
C9D3... Resistor, capacitor, diode, Q2 that constitutes the charging/discharging circuit! Q3... Inverter, R4, R6... Divided resistor.

Claims (1)

[Scope of utility model registration request] A light emitting diode to which a voltage that changes depending on the presence or absence of an abnormality is applied, a phototransistor that receives light from the light emitting diode, a charging/discharging circuit that charges the signal from the phototransistor, and an alarm when the circuit is discharged. It is characterized by comprising an inverter that sends out an output, and a divided resistor that maintains the charging/discharging circuit at ground level when the inverter sends out an alarm output, and memorizes the alarm state even when the system returns to normal. Anomaly detection device.