KR870000653Y1 - Power circuit - Google Patents

Abstract

No content.

Description

2 Overvoltage protection device of power circuit

The accompanying drawings show a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

3: Input power cutoff part 4, 4 ': +,-side load cutoff part

CTR: Breaker L: Breaker Drive Coil

R ₉ -R ₁₃ : Resistor D: Diode

Q ₃ -Q ₅ : Transistor ZD ₃ -ZD ₅ : Zener Diode

SR ₁ , SR ₂ : SCR

The present invention relates to an overvoltage protection device of a two-supply circuit in which a positive power supply and a negative power source are separated.

In the special electronic circuit of OP amplifier circuit or EA-ROM, two power sources separated from each other by (+) side and (-) side are used as driving power source. Conventionally, the two power supply circuits are overloaded or abnormally changed in input voltage. Because of this, there was no protection device to protect the load circuit connected to it when overvoltage occurred, which caused the damage of the load circuit and the occurrence of fire.

The present invention is to solve this problem, by rectifying and smoothing the input AC power, and the constant voltage process to make the two power supply (+) and (-) side separated from each other in the two power circuit overload or overvoltage due to failure In this case, the power supply of the load circuit on the (+) (-) side is immediately turned off, and the AC power input to the 2 power circuit is also cut off so that the load circuit and the 2 power circuit can be protected. If this is described in detail by the accompanying drawings as follows.

Conventional 2 + of the power supply voltage generation unit (2), - side power supply line ⁽⁺ E) ^(- E) to the Zener diode (ZD _4), a resistance (R _11), a transistor (Q ₄₎ and SCR (SR ₁₎ The + side load cut-off part 4 'and the negative side load cut-off part 4' made of the zener diode (ZD ₅ ), the resistor (R ₁₃ ) transistor (Q ₅ ) and the SCR (SR ₂ ), respectively, the +-side power supply line ⁽⁺ E) ^(- E) between the a resistance (R ₉ -R _12), diode (D), Zener diodes (ZD _3), a transistor (Q ₃₎ and a breaker (CTR) The input power cut-off part 3 is connected, where 1 is a commutation and smoothing part, 5.5 'is a load, AC is an AC input power, T is a power transformer, L is a breaker driving coil, and C ₁ -C. ₄ is a capacitor, R ₁ -R ₈ is a resistor, ZD ₁ and ZD ₂ are zener diodes, Q ₁ and Q ₂ are transistors, OP ₁ and OP ₂ are OP amplifiers, PTR ₁ and PTR ₂ are power transistors.

The operation and effects of the present invention as the configuration is as follows.

When high-current power is input to the power transformer (1) through the breaker (CTR) contact, voltage is induced on the secondary side to this power transformer (T), and this voltage becomes DC in the rectification and smoothing part (1) including ripple. It is input to the constant voltage generator 2.

In the constant voltage generator 2, the output voltage of the constant voltage generator 2 compares the voltage divided by the resistors R ₃ and R ₄ with the reference voltage of the zener diode ZD ₁ in the OP amplifier OP ₁ . Therefore, when the reference voltage of the Zener diode ZD ₁ is large, the output of the OP amplifier OP ₁ becomes "HIGH", and the power transistor PTR ₁ is turned "on", thereby outputting the output voltage of the constant voltage generator 2. On the contrary, if the voltage divided by the resistors R ₃ and R ₄ is large, the output of the OP amplifier OP ₁ becomes “LOW”, thereby 'cuting off' the power transistor PTR ₁ . By reducing the output voltage of the constant voltage generator 2, the voltage of the + side power supply line ⁺ E is kept constant. The transistor (Q ₁₎ and a resistor (R ₁₎ in the constant voltage generating section (2) is that the voltage of the resistor (R ₁₎ between both ends increased when the over-current in the resistance (R ₁₎ as a control + side over-current flows, whereby transistor (TR ₁₎ a "turn-on" is the base and the emitter voltage is reduced by being pawooeo transistor (PTR ₁₎ a "cut-off" of transistor pawooeo (PTR _1).

Voltage is also kept constant by the same circuit operation as that when + side of the power supply line ⁽⁺ E) of a constant voltage generating section (2) in ^the-side power supply line (E).

When the constant voltage generator 2 operating as described above is in the normal operating state, the zener voltage of the zener diode ZD _{4 in} the + side load interruption unit 4 of the present guide connected to the + side power line ( ⁺ E) As a result, the voltage for turning the transistor Q ₄ 'on' is not applied between the both ends of the resistor R ₁₁ , so that the transistor Q ₄ is in the 'cut off' state, so that the SCR (SR ₁ ) is also 'cut off'. As a result, a steady voltage is supplied to the load 5.

On the other hand, the operation of the negative side load interrupting unit 4 'in the present invention is also the same as that of the positive side load blocking unit 4, where the zener voltage ZD _{3 in the} input power interrupting unit 3 is positive. Selected as larger than the voltage (Ev) of the side power supply line ( ⁺ E) and less than twice the voltage (2Ev), the circuit consists of a resistor (R ₁₀ ), a zener diode (ZD ₃ ) and a resistor (R ₁₂ ). both ends, the voltage (2Ev) is a current flow to the base of the transistor (Q ₃₎ caught by being there is a transistor (Q ₃₎ thereby "turn-on", whereby the collector potential of the transistor (Q ₃₎ is nearly as OV breaker ( Since no current flows through the driving coil L of the CTR, the driving coil L is not driven and the contact point of the breaker CTR is in an 'on' state.

In this state, when the constant voltage generator 2 becomes an overvoltage state due to an overload state of the positive and negative side loads 5 and 5 'or a self-circuit failure, that is, when the + power source becomes an overvoltage state, As the voltage between both ends of the resistor R _{11 in the} side load cut-off part 5 rises, the transistor Q ₄ is 'turned on', whereby a current flows through the gate of the SCR SR ₁ and thus the SCR SR _1. ) Is 'turned on' so that the output voltage of the + side power line ( ⁺ E) becomes OV so that no voltage is applied to the load 5, and at the same time, the resistors R ₁₀ and Zener in the input power cut-off part 3 are As described above, a voltage Ev is applied between the circuit composed of the diode ZD ₃ and the resistor R ₁₂ as the voltage of the + side power line (+) becomes OV, so that no current flows in the circuit. by a transistor (Q ₃₎ is "off" did not receive the base power supply through a resistance (R ₅₎ and diode (D) As the current flows to the drive coil L of the short term (CTR), the drive coil (L) is driven so that the contact of the breaker (CTR) is 'off', so that the input AC power is cut off. In this case, the same circuit operation as in the case of the + side power supply described above is performed.

As described above, when the overvoltage occurs due to an overload or a failure in the two power circuits, the present invention not only cuts off the power supplied to each load on the + and-side but also cuts off the AC power input to the two power circuits. It is a useful design to prevent the fire by to protect the load and the power circuit.

Claims (1)

Conventional 2 + of the power supply voltage generation unit (2), - side power supply line ⁽⁺ E) ^(- E) to the Zener diode (ZD _4), a resistance (R _11), a transistor (Q ₄₎ and SCR (SR ₁₎ Connect + side load cut-off part 4 and Zener diode (ZD ₅ ), resistor R ₁₃ , transistor Q ₅ and-side load cut-off part 4 'of SCR (SR ₂ ) a resistance (R ₉ -R _12), diode (D), Zener diodes (ZD _3), a transistor (Q ₃₎ and a breaker (CTR) between the +, ^--side power supply line ⁽⁺ E) (E) A two-power overvoltage protection device, characterized in that the input power cut-off unit 3 is connected.