SU815830A1 - Device for protective disconnection in ac network - Google Patents

Description

(54) DEVICE FOR SAFETY SHUTDOWN IN AC POWER NETWORK

Corresponding signals to facilitate troubleshooting operations.

The purpose of the invention is to improve the reliability and ease of operation of relay protection.

This goal is achieved by the fact that a device for protective disconnection in an AC network contains a measuring unit whose output is connected to the input of the fault signaling authority in the forming unit and with an inverted input of the actuator made on the element "Inhibit whose output is connected to to the input of the protection actuation body and to the switch input, a monostable element and a delay element, as well as a fault alarm body in the measuring unit, with it monostable element is included between the output of the forming block and a right input element "ban, and the signaling body fault x in the measuring unit through a delay element coupled to an output of the measuring unit.

The drawing shows a diagram of the proposed device.

The device of protective disconnection in the AC network contains the measuring unit 1, which forms the block 2, the executive body 3, made on the element "Prohibition, the logical element AND 4, the logical element NOT 5, the organ signaling-. the protection act 6, the fault signaling unit in the forming unit 7, the monostable element (one vibrator) 8, the delay element 9 and the fault signaling body in the measuring unit 10.

During normal operation of the protected object and in good condition of the measuring unit, there is no signal at its output. Therefore, there are no signals at the inputs of the forming unit, the logic element, the delay element at the output of the delay element and the alarm signaling unit in the measuring unit. At the output of the logical element is NOT and the input of the logical element associated with it. And there is a signal in this case. In a healthy state of the forming unit, the signal at its output is also absent, therefore, there are no signals at the associated input of the logic element AND, at the input and output of the monostable element, at the direct input of the “Forbidden. There is no signal at the output of the logic element I, at the input of the alarm signaling body in the forming unit, at the inverse input of the element “Forbidden. At the exit of the executive body (the element “Prohibition”) and the entrance of the signaling body about the activation of the protection of signals, there is no. Device is not working.

During normal operation of the protected object, the good condition of the measuring unit and the presence of malfunctions in the forming unit, leading to the appearance of a signal at the output of the latter,

signal at the input and output of the monostable element and at the direct input of the element “Zypret. At both inputs of the logic element AND signals there is, therefore, a signal appears at the output of this element, as well as at the associated inverse input of the element "Prevent the input of the fault signaling authority in the function block. Since both inputs of the “Inhibit signals” element are present, there is no signal at the output. Device is not working

the switch is off, but a malfunction signal is generated in the forming unit.

The signal at the output of the monostable element appears only for a certain time, sufficient for reliable disconnection of the switch of the protected object from this device. After the specified time, the signal from the output of the monostable element disappears, despite the presence of a signal at its input, which leads

5 to the disappearance of the signal at the direct input of the element “Prohibition. This does not lead to a change in the exit state of the element "Prohibition and the entire device as a whole.

If, in the presence of the indicated malfunction in the forming unit of the device, an external short circuit occurs on the elements associated with the protected object, which triggers the operation of the measuring unit, a signal will appear at the inputs of the logical element NOT and the delay element. The signal at the output of the logical element is NOT and the input of the logical element AND associated with it disappears, as a result of which the signal at the output of the latter and at the inverse input of the element “Inhibit. However, by this time, due to the presence of a mono-stable element, there will be no signal at the direct input of element S arpt, which excludes the action of the faulty device. The time of the delay element should be chosen most of the time with which this device acts on the shutdown (for example, longer than the time of the backup protection stage). As a result, a signal about the presence of malfunctions in the measurement panel during external closures appears jg. will not be.

In case of damage on the protected object, the measuring unit of the device comes into action, a signal appears at its input, as well as at the inputs of the forming unit, the logical element HE, and the delay element 5. After a certain time, a signal appears at the output of the forming unit, at the input and output of the monostable element, and at the direct input of the element “Forbidden. There is no signal at one of the inputs of the logical element AND (associated with the logical element NONE), and at the other input (connected with the output of the forming unit) there is a signal. Consequently, at the output of the logic element there is no AND signal, there is no signal at the inverse input of the element “Prohibition. At the output of the element "Prohibition appears a signal, the switch is disconnected and a signal is given that the protection has been activated. There is no signal at the output of the delay element, since the delay time is more than the device action time for switching off the switch. If, as a result of faults in the measuring unit, the signal at the output is long (for example, if the measuring relays do not return to the initial state after the device acts to switch off the switch), then the output of the forming unit and, consequently, at the input of the monostable element, the signal will remain also long. However, at the output of a monostable element, at the direct input of the element “Inhibit” and at the output of the entire device, the signal appears briefly. Therefore, when the protected object is turned on again, the device will not affect its shutdown, since by the time the switch is turned on again, the signal at the output of the monostable element and, therefore, at the device output will disappear. In addition, in the specified mode, a signal appears at the output of the delay element. and the fault alarm body in the measuring unit is operating.

Thus, the reliability of the device and the convenience of its operation increase.

Claims (2)

1. Fedoseev, A. M. Relein, Protection of 30 Electric Systems, M., Energia, 1976, p. 24 2. USSR author's certificate No. 625284, cl. H 02 H 7/00, 1977. I 1СЛ.