JPS6138363Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an inspection circuit for a control power source such as a protective relay device.

In general, transistors and ICs are used in protective relay devices.
In order to prevent erroneous output from being output when the power is turned on or when the power is momentarily interrupted, devices configured with so-called static relays, such as the
(abbreviated as PAL circuit) is required. This PAL circuit is in a standby state under normal conditions (when the power supply is established), and immediately operates when the static relay becomes unable to respond normally due to a momentary power interruption. The output of this static relay and the output of the logic sequence circuit must be locked.
PAL circuits are designed with this point in mind. However, if some abnormality occurs in the PAL circuit itself and normal operation cannot be expected, this must be detected and dealt with.

The conventional method for detecting this has been to constantly monitor whether or not there is a mislock (locking the output of a static relay even when the power supply is normal). There was no confirmation as to whether this was the case.

This invention was devised in view of this point, and PAL
It is an object of the present invention to provide a constant monitoring and inspection device for a controlled power source, which allows checking periodically or at any time to check whether a circuit can exhibit its performance in the event of an abnormality such as a momentary power interruption.

FIG. 1 is a diagram showing an embodiment of a PAL circuit according to the present invention. In the figure, A, B, and C are control power supply buses having voltages of, for example, 24 [V], 12 [V], and 0 [V], respectively. A protection device or a control device 1 is connected between these A-C busbars and between B-C busbars. Then, voltage level detection elements 3A and 3B are connected in series with the A and B buses through contacts 2A and 2B, respectively. The contacts 2A, 2B
is a normally closed contact of an auxiliary relay (not shown) that operates when inspecting the control bus. Further, the voltage level detection elements 3A and 3B are configured as shown in FIG.
4 are connected in series, the base of this transistor 33 is connected to the connection point between the resistor 33 and the Zener diode 32, and the connection point between this resistor 33 and the transistor 34 is connected to a transistor 35 constituting an inverting circuit.
It is connected to the base of 36 is resistance, 3
7 is an output terminal, and D is a bus bar independent from A and B. The Zener voltage of the Zener diode 32 is selected to be, for example, 80% or more of the rated voltage. Therefore, if the power supply voltage VAC is 80% or more of the rated voltage, the Zener diode will conduct.
The transistor 34 is turned off, the transistor 35 is turned on, and the output terminal 37 outputs a "0" signal. Note that the voltage level detection element 3B is also configured in the same manner. 4 is an OR circuit into which the outputs of the voltage level detection elements 3A and 3B are introduced;
When either becomes a "1" signal, an output "1" is produced. When an output is generated in the OR circuit 4, the extension circuit 5 outputs a lock signal and display signal 6 for temporarily protecting or invalidating the output of the control device 1. 7 is an AND circuit, and when the voltage level detection circuits 3A and 3B both output "1", the output 8
occurs.

Now, in the circuits shown in FIGS. 1 and 2, if the voltage on the bus A falls below the expected value, the voltage level detection element 3A operates and outputs a signal "1", and the OR circuit 4 A lock and display signal 6 is output via circuit 5. From this output signal 6, it can be recognized that the voltage on bus A or B has dropped by more than a predetermined value. The same applies when the voltage of the bus line B falls below the expected value. Display signal and lock signal 6
Even if is output, it is not possible to distinguish whether the voltage has dropped on the bus A or B, but the protection and control device 1 is simultaneously taking in voltage from the A and B buses, so even if the voltage on either one drops, it will not output. cannot be trusted. Therefore, it is sufficient to take measures such as displaying that the voltage of one of the busbars has dropped, protection, and locking the output of the control device.

Next, in order to check whether the PAL circuit is normal or not, a check command is given to open the contacts 2A and 2B. Then, since the base current of the transistor 35 is cut off, the transistor 35 is turned off, an output of "1" is generated from the output terminal 37, and an output of "1" is generated from the voltage level detection elements 3A and 3B. As a result, not only the output signal 6 is generated, but also the output signal 6 is generated.
An output signal 8 is generated from the AND circuit 7, and by the generation of this output signal 8, it can be confirmed that the PAL circuit is normal.

FIG. 3 is a diagram showing another embodiment of the present invention.
The normally closed contacts of the switching contacts 2A and 2B that operate according to the inspection command are connected to the power supplies A and B and the voltage level detection element 1A,
1B is connected, and the normally open contact introduces a voltage that can operate voltage level detection elements 3A and 3B divided by resistors R _A1 and R _A2 or R _B1 and R _B2 , so 2A and 2B are connected by inspection command. When activated, the voltage level detection elements 3A and 3B detect a voltage drop, and it can be confirmed in the same manner as in FIG. 1 that the PAL circuit can respond normally. In FIG. 3, an appropriate voltage drop simulation was explained using a method using resistance voltage division, but it does not matter at any time that it may be performed using a method using a Zener diode or the like.

In the case of Figures 1 to 3, the voltage level detection element was able to detect only voltage drops, but in the case of Figure 4,
By configuring as shown in the figure, it is possible to easily check not only voltage drops but also voltage increases.

In FIG. 4, 91 is a resistor, 92 is a Zener diode, 93 is a resistor, 94 is a transistor,
95 is an OR circuit. zener diode 92
is conductive when the voltage is 110% or more of the rated voltage, and non-conductive when it is lower than that.

FIG. 5 shows a case where different power sources can be easily brought in. Switching contact 2A, 2 for inspection
Power supply A', which has a voltage higher than the overvoltage detection level of level detection elements 9A and 9B due to the normally open contact of B
When switched to B', each level detection element 9A, 9B can operate, and confirmation can be made in the same manner as in FIG. In addition, if a different power source cannot be easily used, check commands 10A and 10 as shown in Figure 6.
In this method, the level detecting elements 9A and 9B are controlled by B to forcibly lower the detection level than the normal detection level to enable operation while connected to normal power supplies A and B.

As described above, according to the present invention, it is possible to provide a device that can automatically detect whether or not the function of suppressing the output of a relay or the output of a logic circuit, which may produce an erroneous output when the power supply is abnormal, can be performed. This contributes to increasing the reliability of the device.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of the power supply abnormality detection circuit of the present invention, Fig. 2 is a circuit diagram showing an example of a voltage level detection element, and Figs. 3, 5, and 6 are circuit diagrams showing other embodiments. , FIG. 4 is a diagram showing an example of another voltage level detection element. A, B, C: mutually independent power bus, 3A, 3
B, 9A, 9B: Voltage level detection element, 4: OR
Circuit, 5: Extension circuit, 7: AND circuit.

Claims (1)

[Scope of utility model registration request] In equipment that inspects the power supply of protection or control equipment that requires multiple control power supplies, there are contacts that are connected in series to each of the plurality of control buses and are switched in response to an inspection command, and each of the control buses is connected to each of the control buses through these contacts. a voltage level detection element that is connected to the control power supply voltage and operates to generate an output when the control power supply voltage decreases or increases from a predetermined value, and when any one of the plurality of voltage level detection elements generates an output, the protection or control device A circuit for constantly monitoring and displaying a control power supply, comprising a circuit that generates an output and a display output to lock the output of the power supply, and a circuit that detects that all of the plurality of voltage level detectors are activated during inspection and outputs an inspection confirmation signal. Inspection equipment.