JPS6341246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a responsive relay that has timed characteristics for both activation and return.

For relays that have a time limit for operation and recovery,
An operating value and a return value are set for the input value of the current to be detected, and each has a time limit. Such relays are used, for example, to control phase advance capacitor equipment.

It is well known that in power receiving equipment, as the load increases, the power factor of the load worsens, and a capacitor is generally used to improve this problem. The relay may function to detect the load current and turn on or open the capacitor when the current value exceeds or falls below a predetermined value, but for example, the input current of the relay (secondary current of a current transformer)
If it operates without a time limit when the current exceeds 3 amperes (by closing the capacitor), and if it returns to normal operation without a time limit (by opening the capacitor) when the voltage drops to 2 amperes, the load fluctuates rapidly in a short period of time. Naturally, this is not preferable because the frequency of closing and opening the capacitor increases and exceeds the allowable range of operating duties of the capacitor switch.

For this reason, as described above, the frequency of closing and opening the capacitor is limited by giving certain time limits to each operation and recovery.

Therefore, in the case of conventional relays, a level detection circuit for determining the operating value and a level detection circuit for determining the return value are provided, each with a time limit.
It was equipped with a CR integration circuit. For this reason, four volumes (variable resistors) are required to set the operating value and return value, and to set the operating time limit and return time limit, making the configuration complicated. Further, the operating time limit and the return time limit must be set separately, and if a setting error occurs in which the return value exceeds the operating value, recovery may not be possible in some cases, which is difficult to handle.

An object of the present invention is to provide a relay that eliminates the above-mentioned drawbacks.

The present invention provides a time limit for operation and recovery using one level detection circuit and one CR integration circuit, allows setting of both time limits with one volume (variable resistor), and eliminates errors in setting operation and return values. It is characterized by the following.

The present invention will be explained below based on the drawings. FIG. 1 is a block diagram showing the configuration of the present invention.
is an input transformer that converts the output current of the current transformer CT into an appropriate value, B is a current-voltage conversion circuit that converts the input current to voltage, and C is a level detection circuit that determines the magnitude of the input amount. Then, the operating value and the return value are determined and output. D is a time limit circuit that sets a time limit for operation and return, and E is a switching circuit. After the operation time limit or return time limit, the output relay RY operates or returns to open and close its contact _RY1 .

FIG. 2 shows a specific circuit of the present invention, and FIG. 3 shows its operating characteristics, which will be explained below. The AC load current to be detected is converted into an appropriate value by the input transformer A via the current transformer CT, and is also converted into a current voltage by the conversion circuit B. Here, connect the variable resistor VR ₁ for setting the operating value to the current transformer.
Assuming that the secondary current value of the CT is set to 4 amperes, when this 4 amperes flows, a voltage V ₀ corresponding to it will be generated. This voltage V ₀ is the resistance R ₁ , R ₂
When the operating reference voltage _V1 determined by V1 is exceeded, the output of the first voltage comparator _VD1 is inverted (the second output terminal changes from H to L, and the first output terminal Q changes from L to H). By doing so, the transistor TR ₂ becomes non-conductive and the variable resistor VR ₂ for setting the operation and recovery time
Start charging capacitor _C1 through. When the voltage V ₀ of the capacitor C ₁ reaches the operating reference voltage V ₃ determined by the resistors R ₃ , R ₄ , R ₆ , the output of the second voltage comparator VD ₂ is inverted (the second output terminal is from H to L, the first output terminal Q goes from L to H), which makes the transistor TR ₁ conductive and the output relay
RY operates and closes its contact RY ₁ . A capacitor equipment (not shown) is turned on by this relay output. Then, the diodes D ₅ and D ₆ become reverse biased and are cut off, so the resistance R ₅ and the diode D ₁
The capacitor _C1 is rapidly charged through the capacitor C1 and reaches the supply voltage Vcc.

On the other hand, when the input current decreases, the voltage V ₀ also decreases, and this voltage V ₀ is connected to the diode D ₂ ,
When the voltage falls below the reset reference voltage determined by the reset value setting variable resistor VR ₃ and the resistors R ₁ and R ₂ , the output of the first voltage comparator VD ₁ is inverted (the second output terminal changes from L to H, 1 (from H to L), the capacitor _C1 is discharged through the variable resistor _VR2 for setting the operation and recovery time. Therefore, the voltage Vc gradually decreases and when it reaches the voltage _V3 , the output of the second voltage comparator _VD2 is inverted (the second output terminal changes from L to H, and the first output terminal Q changes from H to L). )
Transistor TR ₁ becomes non-conductive and output relay
RY returns and opens its contact RY ₁ . This return of the output relay opens the capacitor equipment. At the same time, diodes D ₃ and D ₄ become reverse biased and then cut off, causing transistor TR ₂ to conduct and capacitor C ₁ to rapidly discharge. In addition,
As can be understood from Figure 3, the operating time (time limit) from when the input current exceeds the operating value until the relay output (contact RY ₁ closes), and from when the input current falls below the reset value, the relay output The recovery time (time limit) until (contact RY ₁ open) disappears is the same, generally 1 to 2
Sets within minutes.

As described above, according to the present invention, when the input current becomes equal to or higher than the set operating value, charging is started in the CR integration circuit, and after the operating time, the reference voltage is reached and the output relay is operated, and in the case of recovery, the output relay is activated. The operation is completely opposite to that, and the output relay is reset when the current below the reset value exceeds the reset time, so the operation and reset time can be set using a single variable resistor.
Can be done in VR ₂ . Therefore, there is no need to individually set the operation and return times as in the conventional case. Also, until just before operation, the first voltage comparator VD ₁
Since the second output terminal of the diode D2 is at H level, the diode _D2 is reverse biased, so the operation reference voltage is given by the formula: Operating reference voltage=Vcc (power supply voltage)× _R2 / _R1 + _R2 .

On the other hand, since the second output terminal of the first voltage comparator VD ₁ is at L level until just before recovery, the diode D ₂ is forward biased, so the recovery reference voltage = Vcc (power supply voltage) x (R ₂・VR ₃ /R ₂ +VR ₃ ) /R ₁ + (R
₂・VR ₃ /R ₂ +VR ₃ ). Since R ₁ and R ₂ are fixed values,
The return value can be set independently of the operating value using only VR ₃ , and as described above, the return reference voltage is always below the operating reference voltage, that is, the return value is always below the operating value, so there is no possibility of setting errors. As described above, according to the present invention, it is possible to provide a relay that has a simple circuit configuration and is easy to handle. It is particularly useful as a control relay for capacitor equipment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of the present invention, FIG. 2 is a circuit diagram showing a specific example of the invention, and FIG. 3 is a time chart for explaining its operation. A...Input transformer, B...Current-voltage conversion circuit, C...Level detection circuit, D...Time limit circuit, E
... Switching circuit, VD ₁ , VD ₂ ... First and second voltage comparators, RY ... Output relay, D ₁ , D ₂ ,
D ₃ , D ₄ , D ₅ , D ₆ ...first, second, third, fourth,
Fifth and sixth diodes.

Claims (1)

[Claims] 1. A conversion circuit that converts the AC input amount to be detected into a voltage proportional to the AC input amount, a rectification circuit that rectifies the voltage from the conversion circuit, and a DC voltage obtained by smoothing the voltage from the rectification circuit. a first reference voltage determined by a fixed resistor of
a voltage comparator, and after the first voltage comparator detects that the DC voltage exceeds the reference voltage, inputs the DC output voltage of the first output terminal of the first voltage comparator. The CR integrator circuit and the above
a second voltage comparator that compares the DC voltage from the CR integration circuit with a second reference voltage; the CR integration circuit is configured with a series circuit of a first variable resistor and a capacitor; a circuit for rapidly charging the capacitor, the circuit comprising a series circuit of a fifth fixed resistor and a first diode connected between a connection point of the capacitor and a power source; The connection point of the first diode and the first diode
and fifth and sixth diodes connected between the respective first output terminals of the second voltage comparator, and the DC output voltage of the first output terminal of the second voltage comparator. an output relay energized by conduction of the first transistor; a second transistor for rapid discharge connected in parallel with the capacitor; and a second transistor connected in parallel with the capacitor; from the base electrode of the first
and third and fourth diodes connected toward the second output terminal of the second voltage comparator, respectively;
1. A time-responsive relay comprising a series circuit of a second diode and a second variable resistor connected toward an output terminal.