JPS60239816A - Power supply failure signal output circuit of measuring instrument - Google Patents

Abstract

PURPOSE:To prevent a power supply failure signal from misoutput at the disconnection of the input of the power supply by forming a voltage dropping means for turning the output of a DC power supply for failure output suddenly to zero at the OFF of the input of the power supply. CONSTITUTION:At the disconnection of the input of the power supply, the output of the measuring DC constant voltage power supply 1a is suddenly dropped and applied to a power supply failure detecting circuit 2. When the input voltage reaches an open voltage, a relay 2a in the circuit 2 is actuated, so that a relay contact 3c is closed with the delay of time t2 from the OFF of the power supply input. On the other hand, a relay 7a in the voltage dropping means 7 is turned off simultaneously with the OFF of the power supply input, a relay contact 7b is closed and a load resistor RL1 is connected to the DC power supply 4 for failure output. The value of the resistor RL1 is set to a low value so that the output voltage dropping speed of the power supply 4 is higher than the voltage dropping speed of the power supply 1a. The output of the power supply 4 is applied to a failure signal connecting circuit 3 and a relay 3a is actuated with the delay of time t4 from the OFF of the power supply input. Consequently, t2- t4 is formed, and after opening a relay contact 3b, the contact 3c is short-circuited. Therefore, no failure signal is outputted even at the disconnection of the power supply input.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a measurement power supply failure signal output circuit for a measuring instrument such as a data recording device that continuously records data on natural phenomena such as brightness and illuminance over a long period of time.

Conventional configuration and its problems In recent years, when designing tunnel lighting, it has become necessary to continuously record outdoor brightness values and vertical illuminance values at the tunnel entrance over a long period of time.

A power failure compensation type data recording device is used as a device for recording such signals. This data recording device requires unattended operation, and as a result, the operating status of the data recording device is often monitored by remote monitoring and control. Therefore, data recording devices are required to have a function that reliably informs the outside of the failure state of the device.

A conventional power failure output circuit for a measuring instrument such as a data recording device will be described below.

Fig. 4 shows the power supply unit and power failure output circuit of a conventional data recording device, where 1 is the measurement power supply unit, 2 is the power failure detection circuit, 3 is the failure signal output control circuit, and 4 is the failure output. It is a DC power supply for use.

The measurement power supply 1 further includes a measurement DC constant voltage power supply 1a, a charging side control circuit 1b, a chargeable batch 1J1c, a straddle contact (A contact) 1d, a backflow blocking diode 1f, a voltage converter 1e, and a power supply detection circuit. 'q-, relay 1h. The power failure detection circuit 2 is shown as an example configured with a relay 28. The fault signal output control circuit 3 is the relay 3.
This is an example in which the relay contacts 3b and 3c are used.

The operation of the conventional power failure detection circuit configured as described above will be described below with reference to waveforms at various parts in FIG.

Power input (commercial frequency AC1ooV is generally used)
is applied in parallel to the measurement power supply section 1 and the failure output DC power supply 4. In the measurement power supply unit 1, the measurement DC constant voltage power supply 1a supplies the DC voltage v1 necessary for the measurement operation of the data recording device.
is converted to The output of the measurement DC constant voltage power supply 1a is 3
One is supplied to the charging control circuit 1b.

The charging control circuit 1b is composed of a current limiting resistor R1 and a reverse current blocking diode D1, and controls the charging current to the batch IJ1c, and also causes the charge of the battery to flow back to the measurement DC constant voltage power supply 1a when the battery is operated. to prevent The second voltage of the DC constant voltage power supply 1a for measurement is normally the voltage v2 required as an open circuit to charge the battery 1c.
The voltage converter 1e converts it into a voltage v2. FIG. 4 shows an example in which a forward voltage drop of a rectifying diode D2 is used as a voltage converter, but this is a general form. The output of the charging control circuit 1b is connected to the battery 1c through the relay contact (A contact of the relay 1h).
connected to. Further, a backflow blocking diode 1f is connected between the output of the charging control circuit 1b and the output of the voltage converter 1e so that the charging control circuit 1b side serves as an anode. This backflow blocking diode 1f supplies charge from the battery IJ1c to the battery-operated clock side circuit system, and during power input (Ac1ooV) operation, separates the charging operation of the batch]1c from the power supply to the measurement circuit and system. , a power supply path is secured from the measurement DC constant voltage power supply 1a to the measurement circuit system through the voltage converter 1e. The voltage ■2 of the measurement circuit system is applied to the voltage detection circuit 1q, and the voltage ■2 is applied to the constant voltage diode D3.
When the voltage is higher than the voltage determined by , transistor Q is turned on, relay 1h is operated, and relay contact 1d is closed. As a result, it is possible to charge the battery when there is power input, and it is possible to supply power from the battery when the battery is operating. When the voltage v2 becomes lower than the voltage determined by the constant voltage diode D3, the base current of the transistor Q is limited by the resistor R2, and as a result, the transistor Q is turned off.
Turn off relay 1h, open relay contact 1d, and disconnect batch 1J1c from the power supply circuit. In this manner, the voltage detection circuit 1q operates to prevent over-discharge of the battery 1C and to prevent the supply voltage (2) to the measurement circuit system from dropping too much.

Next, the third output of the measurement DC constant voltage power supply 1a is applied to the power supply failure detection circuit 2. FIG. 4 shows an example in which the power failure detection circuit 2 is constituted by a relay 2a that operates based on the voltage 1. When the power supply input is turned on (see FIG. 5(a)), when the output of the measurement DC constant voltage power supply 1a, that is, the voltage drops, the relay 2a is turned on at voltage 3 after time t1 has elapsed. This is because the change in the output voltage of the measurement DC constant voltage power supply 1a is delayed as shown in the waveform (b) in Figure 6, and the open circuit voltage of the relay 2a is lower than the sensing voltage ■3 and operates with hysteresis. It's for a reason. Similarly, turn off the power input
After time t2 (see Figure 5 (a)), the voltage ■
4, the relay 2a is turned off. , the operating state of the relay is shown in the waveform (c) of Figure 5. Here, tl and t2 are generally not equal in many cases due to the characteristics of the DC constant voltage power source for measurement and the characteristics of the relay.

On the other hand, the power input (AClooV) is applied to the fault output DC power supply 4, causing a delay in the operation of the fault output DC power supply 4 as shown in FIG. The output (voltage V5) of the fault output DC power supply 4 is sent to the fault signal output control circuit 3 and drives the relay 3a. At this time, depending on the operating characteristics of the relay 38, the output of the relay 3a is delayed by t3 when the power input is 9N and t4 when the power input is OFF, as shown in FIG. Relay 3a has relay contact 3b (a contact),
Relay 2a is connected to relay contact 3c (b contact).

Furthermore, relay contacts 3b and 30 are connected in series and output a fault signal.

If the measurement DC constant voltage power supply 1a fails and its output voltage v1 becomes zero, the relay contact 3C is closed. At this time, if there is a power input, the relay contact 3b closes and outputs a failure signal. On the other hand, when the power input is turned off, relay contact 3b opens.

3C is closed and no fault signal is output. When the relay is still operating normally, the relay contact 3b is closed and the relay contact 3c is open, and similarly no failure signal is output. In this way, the state of the power supply input is taken into consideration, and a failure signal is output only when the DC constant voltage power supply for measurement has failed and when there is a current input.

However, in the above configuration, when the load resistance of the measurement DC constant voltage power supply 1a is small and the load resistance of the fault output DC power supply 4 becomes large, the power supply input is turned on and off.
In operation, the output change of the failure output DC power supply 4 is delayed with respect to the output change of the measurement DC constant voltage power supply 1a, so the delay time shown in FIG. t2 becomes t4. As a result, a problem arises in that a failure signal is output for (14-12) hours when the power input is turned off (waveform (g) shown in FIG. 4), causing false detection in remote monitoring control and the like.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems, and it is an object of the present invention to provide a power supply failure signal output circuit that prevents instantaneous failure signal output when power input is cut off.

Structure of the Invention The present invention includes a power supply failure detection circuit that detects a failure in a DC constant voltage power supply for measurement, a DC power supply for failure output, and a DC power supply for failure output that is connected to the DC power supply for failure output and only when the power supply is cut off. A power supply failure signal output circuit comprising a voltage reduction means for rapidly reducing the output voltage to zero, and a failure signal output control circuit for outputting a failure signal from the output of a DC power supply for failure output and the output of a power supply failure detection circuit, A fault output DC power supply and a voltage reduction means connected in parallel to the fault output DC power supply prevent erroneous output of a fault signal when the power is turned on.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows a configuration diagram of a power failure signal output circuit in an embodiment of the present invention. In FIG. 1, reference numeral 1 designates a power supply unit for measurement, 2 a power supply failure detection circuit, 4 a DC power supply for failure output, 3 a failure signal output control circuit, and 7 voltage reduction means. Here, the measurement power supply section 1, the power supply failure detection circuit 2, the fault output DC power supply 4, and the fault signal output control circuit 3 have the same configuration as in FIG. 4, and the details of the open side power supply section 1 will be omitted.

FIG. 1 shows one embodiment of the voltage reduction means 7. The voltage reduction means 7 is connected in parallel to the fault output DC power supply 4, and includes a relay 7a operated by power input, and a fault output DC power supply 4.
Load resistor RL1 and relay contact 7b connected to the output of
(b contact of relay 7a). Furthermore, load resistor RL1 and relay contact 7b are connected in series.

The operation of the power failure signal output circuit of this embodiment configured as described above will be explained with reference to the waveforms of each part in FIG. 2.

First, the operation when the power input goes from OFF to ON will be described. When the power input turns from OFF to ON as shown in Figure 2 (a), the output of the measurement DC constant voltage power supply 1a in the measurement power supply section 1 increases at a rapid rate as shown in Figure 2 (b). The output of the DC constant voltage power supply 1a for zero measurement, which reaches the voltage v1, is sent to the power supply failure detection circuit 2.

In the power failure detection circuit 2, the relay 2a operates when the input voltage reaches 3. This is the open circuit voltage v4 of relay 2a.
This is because the voltage is lower than the emotional voltage v3. Therefore, since the contact 3C of the relay 2a is a B contact, it operates with a delay of t1 from when the power is inputted, as shown in FIG. 2P. On the other hand, when the power supply input to the fault output DC power supply 4 is turned on, the rising speed of its output voltage (6) is slower than the rising speed of the output voltage (1) of the measurement DC constant voltage power supply 1a.

A voltage reduction means 7 is connected in parallel to the fault output DC power supply 4, but the relay 7a operates at the same time as the power input is turned on, and the relay contact 7b (b contact of the relay 7a) is opened, causing the load resistor RL1 to fail. It is disconnected from the output DC power supply output. As a result, the fault output DC power supply output is directly applied to the fault signal output control circuit 3, resulting in a voltage waveform shown in FIG. Then, as shown in FIG.
It operates with a delay of t3. At this time, t3>tl
A relationship has been established. Therefore, the failure signal output control circuit 3 does not output a failure signal when the power is turned on, as shown in FIG. 2 (G).

Next, the operation buttons when power input is cut off will be explained. When the power supply is cut off (when the power supply input is OFF), the output of the measurement DC constant voltage power supply 1a rapidly decreases as shown in FIG. 2 (b). The output of the measurement DC constant voltage power supply 1a is connected to a power supply failure detection circuit. The relay 28 in the power failure detection circuit 2 operates when the input voltage reaches v4 (open circuit voltage of the relay), and as a result, as shown in Fig. 2 (c), the voltage decreases from t to when the power supply input is OFF.
After a delay of 2, relay contact 3c (b contact) is closed. On the other hand, at the same time as the power input is turned OFF, the relay a in the voltage reducing means 7 is turned OFF, and the relay contact 7b (relay 7
The a and b contacts are closed, and the load resistor RL is connected to the output of the fault output DC power supply 4. Here, the value of the load resistor RL1 is set small so that the voltage drop rate of the output of the fault output DC power supply 4 is faster than the voltage drop rate of the measurement DC constant voltage power supply. The output of the fault output DC power supply 4 is applied to the fault signal control circuit 3, and the relay 3a is connected to the circuit shown in FIG.
As shown in Figure 2, it operates with a delay of t4 from when the power input is turned off. As a result, t2>t4, and relay contact 3
After b (contact A) is opened, relay contact 3c (contact B)
becomes a short circuit. Therefore, as shown in FIG. 2 (g), no failure signal is output even when the power supply is cut off.

Another embodiment of the voltage reduction means 7 is shown in FIG.

In FIG. 3, when the power is turned on, relay 78 immediately operates, relay contact 7C (!J layer a contact a) closes, and the fault output DC power output is transmitted to relay 3a. Therefore, the increase characteristic of the output voltage of the fault output DC power supply when the power is turned on is directly applied to the relay 3a. On the other hand, when the power supply is cut off, relay 7a immediately turns OFF.
The relay contact 7C is opened and the fault output DC power supply output beam is disconnected from the relay 3a. As a result, the input voltage of the relay 3a becomes approximately equal to the waveform shown in FIG. 2), and as shown in FIG. 2(g), no failure signal is output even when the power supply is cut off.

As described above, according to this embodiment, by providing a voltage reduction means that quickly brings the DC power supply output for failure output to zero when the power supply input is OFF, it is possible to prevent the erroneous output of a power supply failure signal when the power supply input is OFF. I can do it.

In the above embodiment, the measurement DC constant voltage power supply output v1 is input to the power supply failure detection circuit, but if the measurement circuit voltage 2 is input to the power supply failure detection circuit, a failure signal is generated during battery operation. can be prevented from outputting.

Effects of the Invention The power supply failure output circuit of the present invention includes a power supply failure detection circuit connected to a DC constant voltage power supply for measurement, a DC power supply for failure output, and a DC power supply for failure output, and outputs a failure only when power input is interrupted. By providing a voltage reduction means for rapidly reducing the output voltage of the DC power supply for use to zero, and a failure signal output control circuit for outputting a failure signal from the output of the DC power supply for failure output and the output of the power supply failure detection circuit, It is possible to prevent an erroneous failure signal from being output when the input (AC1ooV) is cut off, which has a great practical effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a power failure signal output circuit according to an embodiment of the present invention, FIG. 2 is a waveform of each part of FIG. 1, FIG. 3 is another embodiment of the voltage reduction means, and FIG. 4 is a conventional one. FIG. 5 is a block diagram of the power supply failure signal output circuit, and FIG. 5 shows waveforms of each part in FIG. DESCRIPTION OF SYMBOLS 1...-Measurement power supply unit, 2...-Power failure detection circuit, 3...-Failure signal output control circuit, 4. DC power supply for fault output, 7...-Voltage reduction means, 1a-... DC constant voltage power supply for measurement, 1cm/battery, 1h, 2a. 3a, 7a...Relay. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 7'-Han 1M- Figure 5

Claims (1)

[Claims] A DC constant voltage power supply for measurement that receives power input and converts it to the DC voltage necessary for the measurement circuit, a power supply failure detection circuit that detects a failure in the DC constant voltage power supply for measurement, and a DC power supply for failure output connected to the power supply input. and voltage reduction means that is connected to the fault output DC power supply and immediately reduces the output voltage of the fault output DC power supply to zero when the power supply is cut off, and the fault output DC power supply output and the power supply failure detection circuit output are connected in series. A power supply failure signal output circuit for a measuring instrument, comprising: a failure signal output control circuit connected to the measurement DC constant voltage power source and outputting a failure signal of the measurement DC constant voltage power supply.