JPS6321151Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power failure detection circuit used for power sources of electrical equipment, etc.

Conventionally, when a power outage occurs in equipment that uses electricity as its main source, it is possible to restart the equipment by displaying the power outage history, distinguishing between manual operation and power recovery after a power outage, when a power outage occurs during operation. A power outage detection circuit is provided to control the state.

Figure 1 shows an example of a conventional power outage detection circuit, which is used, for example, in a power outage history display circuit for ultra-low temperature storage. There is.
In FIG. ₁ , a series circuit consisting of a delay relay 11 with a time limit T ₁ and a b contact 12b of an auxiliary relay 12 is connected between terminals S ₁ and S ₂ on the power side of the power switch SW 1, and the load of the power switch SW ₁ is side terminal L ₁ ,
The above relay 12 and the auxiliary relay 13 are connected between L ₂ ,
A series circuit with the a-contact 11a of the delay relay 11 is connected, and the a-contact 13a of the relay 13 is connected between the terminal _L1 and the relay 13 in parallel with the a-contact 11a.

The detection operation of this conventional power failure detection circuit will not be described in detail, but its outline is shown in FIG. 2.

Figure 2 shows the various parts for the case where the power is turned on at time t ₁ , switch SW ₁ is closed at time t ₂ , power is cut off at time t ₃ , power is restored at time t ₄ , and switch SW ₁ is opened at time t ₅ . The operating state is shown as a time chart, and symbols a to i indicate the following, respectively.

a... Voltage state of the power supply b... Open/close state of switch SW ₁ c... Excitation state of the coil of the delay relay 11 d... Open/close state of the A contact 11a e... Excitation state of the coil of the relay 12 f... Open/close state of the B contact 12b g... Excitation state of coil of relay 13 and a contact 1
Open/close state of contact 3a h... Open/close state of contact b 13b i... lighting state of indicator light 14 As is clear from FIG. For example, as shown in Figure 1, the indicator light 14 may be turned on when the power is restored.
Alternatively, a power outage can be detected by operating other control circuits.

Using the above circuit, it is possible to achieve the purpose of a power outage detection circuit, but the
Since there is a part of the detection circuit on the power supply side of SW ₁ , it consumes power even when the equipment is stopped, and during maintenance and inspection, even if switch SW ₁ is opened, the delay relay 11 circuit is not activated. Since it is energized, it is not desirable for safety reasons.

On the other hand, there are circuits that use a battery in addition to the power supply for the equipment to detect power outages, but there are problems with the complexity of the circuit and the maintenance of the battery.

The present invention was proposed in view of the above-mentioned conventional circumstances, and aims to provide a power outage detection circuit that does not consume power when the power is turned off and ensures safety during maintenance and inspection. It is.

The above purpose is to provide a power failure detection circuit for use in electrical equipment, etc., which is equipped with a keep relay having at least two contacts, and the keep relay is configured to operate as long as the power switch of the equipment is closed even during a power outage. The plurality of contacts maintain the operating state before the power outage, and the restoration of the power outage is detected based on the operating state of one or more contacts among the plurality of contacts and the voltage state applied to the power outage detection circuit. and a circuit for energizing the reset coil of the keep relay includes another contact of the plurality of contacts, and when the power switch is opened, the reset coil is energized and the power failure detection circuit is placed in a no-voltage state. This is achieved by a power outage detection circuit characterized by:

An embodiment of the present invention will be described below based on the accompanying drawings. FIG. 3 shows one embodiment of the present invention.

In Figure 3, symbols S ₁ and S ₂ indicate the power supply side terminals,
L ₁ and L ₂ are load side terminals, and SW ₃ is a power switch having a closing contact and an opening contact. The set coil S of the keep relay 31 is connected to the terminal _L1 via the time-limited operation a contact 32a of a delay relay 32, which will be described later, and the reset coil R of the keep relay 31 is connected to the terminal L1 of the switch _SW3 via the a contact 31a of the keep relay. Connected to an open contact.
Symbol 32 is a delay relay with time limit T ₂ and is connected between terminals L ₁ and L ₂ . Auxiliary relay 33
is the terminal via the b contact 31b of the keep relay 31.
Connected between _L1 and _L2 . The above b contact 31b
Furthermore, the a contact 33a of the relay 33 is connected in parallel.

In this embodiment, as will be described later, a power outage is detected based on the operating state of the relay 33.
This will activate indicator lights and other devices, or control the restart of equipment when power is restored. As an example, FIG. 3 shows a case where the indicator light 34 is connected between the terminals L ₁ and L ₂ via the b contact 33b of the relay 33.

FIG. 4 shows a time chart of the operating states of each part of the circuit of the embodiment shown in FIG.

In Figure 4, the power is turned on at time t _a and switched on at time t _b .
Switch SW ₃ to the closed side, power outage at time t _c , power restored at time t _d ,
This shows the case where switch SW ₃ is connected to the open side at time _te . In FIG. 4, symbols A to K indicate the following, respectively.

A... Voltage state of the power supply B... Open/close state of switch SW ₃ C... Excitation state of the coil of the delay relay 32 D... Open/close state of the time-limited operation a contact 32a E... Excitation state of the set coil S F... Excitation state of the reset coil R G... Opening/closing state H of the a contact 31a... Opening/closing state I of the b contact 31b... Excitation state of the coil of the relay 33 and the open/close state J of the a contact 33a... Opening/closing state K of the b contact 33b... Lighting state of the indicator light 34. The operation of the circuit shown in FIG. 3 will be explained with reference to FIG. First, the power is turned on at time t _a . At this time, as long as switch SW ₃ is connected to the open side, there is no change in the circuit. Then switch at time t _b
When SW ₃ is set to the closed side, the relay 33 is energized via the B contact 31b, its A contact 33a is closed, and the relay 33 is self-held. At the same time, the B contact 33b
is opened, and the delay relay 32 is energized and closes its a contact 32a after a time period _T2 . This excites the set coil S of the keep relay 31, closing its a contact 31a and opening its b contact 31b. When a power outage occurs at time _tc , the set coil S of the keep relay 31, the delay relay 32, and the relay 33 are de-energized, the a contacts 32a and 33a are opened, the b contact 33b is closed, but the a contact 31a remains closed, and the b contact 31b remains closed.
remains open. When the power is restored at time _td , the set coils S of the day relay 32 and keep relay 31 function in the same way as when switch SW ₃ is turned on, but
Since the B contact 31b of the keep relay 31 remains open, the relay 33 is not energized and its A contact 31b remains open.
3a is open, and b contact 33b remains closed.
Therefore, the indicator light 34 lights up only when the power is restored after a power outage, and it becomes possible to determine whether the operation of the device is due to the activation of the switch SW ₃ or due to the power restoration after a power outage. When switch SW ₃ is connected to the open side at time t _e ,
Since the a contact 31a of the keep relay 31 is closed, the reset coil R is energized, the a contact 31a is opened, and the b contact 31b is closed, and each part of the circuit is returned to its original state, that is, before time t _b . Return to state. At this time, since the a contact 31a of the keep relay 31 is open, this circuit does not consume power, and the danger during maintenance and inspection is also eliminated.

As explained above, in the circuit of the present invention, when the operation of the equipment is stopped, no current flows through the circuit, and it not only operates as a power failure detection circuit but also stops the operation of the equipment. This has the effect of not consuming unnecessary power and eliminating risks during maintenance and inspection.

Note that if a non-contact relay is used instead of the relay 33, it is also possible to detect an instantaneous power outage within the operating time of the contact type relay.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional power failure detection circuit, Figure 2 is a time chart of the operating status of each part of the circuit in Figure 1, and Figure 3 is a circuit diagram of an embodiment of the power failure detection circuit of the present invention. FIG. 4 is a time chart of the operating states of each part of the circuit shown in FIG. 31...Keep relay, 31a...A contact of keep relay, 31b...B contact of keep relay, R...Reset coil of keep relay, S...Set coil of keep relay, SW ₃ ...Power switch.

Claims (1)

[Scope of utility model registration request] For power outage detection circuits used in electrical equipment, etc.
a keep relay having at least two contacts; the keep relay maintains the operating state before the power outage as long as the power switch of the device is closed even during a power outage; The plurality of contacts are connected to a circuit that detects restoration of a power outage based on the operating state of one or more contacts among the plurality of contacts and the voltage state applied to the power outage detection circuit, and energizes the reset coil of the keep relay. 1. A power outage detection circuit comprising another contact among the contacts, wherein opening of the power switch energizes the reset coil to bring the power outage detection circuit into a no-voltage state.