JP6770879B2 - AC / DC voltage detector - Google Patents

Description

The present invention relates to an AC / DC voltage detector capable of detecting the presence or absence of both DC and AC voltages and performing DC voltage detection via a human body.

Conventionally, as shown in FIG. 6, as a voltage detector capable of detecting DC 201 via the human body 101, a part of the circuit is exposed on the surface of the case 102, and the exposed portion 103 is held by one hand. Some perform DC voltage detection by touching the ground 202 with the other hand.

However, as shown in FIG. 7, when the above-mentioned voltage detector is used for the voltage detection of the AC 203, the voltage detection with the insulating gloves worn is performed with the exposed portion 103 held by the bare hands. There is a risk that the sensitivity will be significantly reduced and the charging path will be erroneously determined as a non-charging path.

Therefore, the present invention has been proposed to solve the above-mentioned problems of the conventional voltage detectors, and when performing AC voltage detection, voltage detection with insulating gloves and bare hands are performed. It is an object of the present invention to provide a new AC / DC voltage detector in which the sensitivity difference from the voltage detection in the above state is reduced.

The present invention has been proposed to solve the above problems, and the first invention (the invention according to claim 1) includes a detector that comes into contact with an AC power source or a DC power source to be detected. A first reading resistor R1 having an input end connected to the detector, a protection resistor R2 connected in series with the first reading resistor R1, and a protection resistor R2 connected to the output end of the protection resistor R2 and contacted by a human body. The circuit exposed portion is connected to the output end of the first reading resistor R1, the output end is connected to the circuit ground, and the second reading resistor R3 has a resistance value larger than that of the first reading resistor R1. The presence or absence of charging of the voltage detection target is determined by the total value of the potential difference V1 between both ends of the first reading resistor R1 and the potential difference V2 between both ends of the second reading resistor R3. It is a characteristic AC / DC voltage detector.

According to the AC / DC voltage detector according to the present invention, when performing AC voltage detection, the sensitivity difference between the voltage detection with the insulating gloves worn and the voltage detection with the bare hands is small. A voltage detector can be provided.

It is an equivalent circuit diagram which shows the state which there is a possibility that a non-charging path is erroneously determined as a charging path by a conventional voltage detector. It is an equivalent circuit diagram which shows the state which the AC voltage detection is performed with bare hands by the conventional voltage detector. It is an equivalent circuit diagram which shows the state which carries out the AC voltage detection by wearing the insulating glove by the conventional voltage detector. It is an equivalent circuit diagram which shows the state which performs the AC voltage detection with bare hands by the AC / DC voltage detector of the embodiment of this invention. It is an equivalent circuit diagram which shows the state which performs the AC voltage detection by wearing the insulating glove by the AC / DC voltage detector of the embodiment of this invention. It is a side view which shows the state which the DC voltage is detected by the conventional voltage detector. It is a side view which shows the state which AC voltage is detected by the conventional voltage detector.

Hereinafter, the voltage detector according to the best mode for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 is an equivalent circuit diagram showing a state in which a conventional voltage detector may erroneously determine a non-charging path as a charging path.

As shown in FIG. 1, the voltage detector includes a detector 1 that is in contact with a voltage detection target, a read resistor R1 whose input end is connected to the detector 1, and a protection resistor R2 that is connected in series with the read resistor R1. And a circuit exposed portion 2 connected to the output end of the protection resistor R2 and brought into contact with the human body. The output end of the read resistor R1 is connected to the circuit ground (GND). The resistance between the DC power supply V and the detector 1 is the insulation resistance R. Let Rp be the resistance value of the human body (measurer) in contact with the circuit exposed portion 2. The potential difference (i × R1) between both ends of the reading resistor R1 is the detection voltage.

In this specification, symbols such as i, R, V, and Z indicate each component (member), and indicate its current value, resistance value, voltage value, and impedance value.

In an AC / DC voltage detector with high internal impedance, even if the voltage detection point is a non-charged circuit, if the insulation state with the adjacent electric circuit is poor, the current i will be generated from the adjacent charging unit V via the insulation resistor R. There is a risk of erroneous determination as a flow or charging path.

In order to reduce the influence of such wraparound, it is necessary to reduce the internal impedance (R1 + R2) of the voltage detector within a range that does not affect the human body. The resistance Rp of the human body is a sufficiently small value as compared with the internal impedance (R1 + R2).

FIG. 2 is an equivalent circuit diagram showing a state in which AC voltage is detected by a conventional voltage detector with bare hands.

When the AC power supply is detected by the voltage detector with bare hands, as shown in FIG. 2, an impedance ZC1 due to capacitance is generated between the circuit GND of the voltage detector and the human body. In addition, impedance ZC is generated due to the capacitance between the human body and the ground. The human body comes into contact with the circuit exposed portion 2 with bare hands.

A current i1 flows through the protection resistor R2. A current i2 flows through the impedance ZC1. Therefore, the current i flowing through the read resistor R1 is i = i1 + i2. The presence or absence of charging of the electric circuit V is determined by the potential difference V1 (= i × R1) between both ends of the reading resistor R1 based on the current i flowing through the reading resistor R1.

In this case, since the impedance ZC1 is sufficiently larger than the protection resistor R2 (ZC1 >> R2), the current i1 flowing through the protection resistor R2 is sufficiently larger than the current i2 flowing through the impedance ZC1 (i1 >> i2), and the reading resistor R1 is set. The flowing current i is substantially equal to the current i1 flowing through the protection resistor R2 (i≈i1).

FIG. 3 is an equivalent circuit diagram showing a state in which insulating gloves are worn by a conventional voltage detector to detect AC voltage.

When the AC power supply is detected by wearing insulating gloves with this voltage detector, as shown in FIG. 3, the impedance ZC1 due to the capacitance between the circuit GND of the voltage detector and the human body, and the distance between the human body and the ground The impedance ZC due to the capacitance remains as it is, and the impedance ZC2 is generated between the circuit exposed portion 2 and the human body. The human body comes into contact with the circuit exposed portion 2 via insulating gloves.

Due to the influence of the impedance ZC2, the current i1 flowing through the protection resistor R2 is greatly reduced to become the current i1'. In this voltage detector, as described above, the current i flowing through the reading resistor R1 is substantially equal to the current i1'flowing through the protection resistor R2 (i≈i1'), and the potential difference V1 between both ends of the reading resistor R1 is substantially equal to the current i1'. Is decided. The determination value V'(≈i1' × R1) is significantly reduced as compared with the determination value V (≈i1 × R1) when the voltage is detected with bare hands.

That is, the sensitivity of the voltage detector is significantly lowered, and the lower limit of detection is raised. For example, when the lower limit of detection of electric voltage detection with bare hands is about 30 V, the lower limit of detection becomes about 150 V (5 times) when wearing insulating gloves, and the electric circuit of about 100 V is erroneously determined as a non-charged circuit. It will be.

FIG. 4 is an equivalent circuit diagram showing a state in which AC voltage detection is performed with bare hands by the AC / DC voltage detector according to the embodiment of the present invention.

As shown in FIG. 4, the AC / DC voltage detector according to the present invention has a detector 1 that comes into contact with an AC power supply V or a DC power supply to be detected, and a first reader whose input end is connected to the detector 1. The resistor R1, the protection resistor R2 connected in series with the first read resistor R1, the circuit exposed portion 2 connected to the output end of the protection resistor R2 and contacted by the human body, and the output end of the first read resistor R1. It is provided with a second read resistor R3 which is connected to the circuit ground (GND) and has a resistance value larger than that of the first read resistor R1.

In this AC / DC voltage detector, the voltage detection target V is charged by the total value (V1 + V2) of the potential difference V1 between both ends of the first reading resistor R1 and the potential difference V2 between both ends of the second reading resistor R3. Determine the presence or absence.

When the AC power supply is detected by the voltage detector with bare hands, as shown in FIG. 4, an impedance ZC1 due to capacitance is generated between the circuit GND of the voltage detector and the human body. In addition, impedance ZC is generated due to the capacitance between the human body and the ground. The human body comes into contact with the circuit exposed portion 2 with bare hands. A current i2 flows through the second reading resistor R3.

FIG. 5 is an equivalent circuit diagram showing a state in which insulating gloves are worn and AC voltage is detected by the AC / DC voltage detector according to the embodiment of the present invention.

When the AC power supply is detected by wearing insulating gloves with this voltage detector, as shown in FIG. 5, the impedance ZC1 due to the capacitance between the circuit GND of the voltage detector and the human body, and the distance between the human body and the ground The impedance ZC due to the capacitance remains as it is, and the impedance ZC2 is generated between the circuit exposed portion 2 and the human body. The human body comes into contact with the circuit exposed portion 2 via insulating gloves.

Comparing the case where the AC power supply is detected with bare hands and the case where the AC power supply is detected by wearing the insulating gloves in this voltage detector, when the insulating gloves are worn, the circuit exposed portion 2 and the human body Due to the influence of the impedance CZ2 due to the capacitance generated during the period, the current i1 flowing through the protection resistor R2 is greatly reduced to become the current i1'. Therefore, the potential difference V1 (= i'× R1 ≈ i1 ′ × R1) between both ends of the first reading resistor R1 is significantly reduced as compared with the potential difference V1 (≈i1 × R1) when the voltage is detected with bare hands. To do.

However, when the insulating gloves are worn, the current i2 flowing through the second reading resistor R3 increases and becomes the current i2'. The potential difference V2 between both ends of the second reading resistor R3 is [i2 × R3] when detected with bare hands, and [i2 ′ × R3] when wearing insulating gloves, and the insulating gloves are worn. The case is higher.

In this voltage detector, the determination value V is the total value (V1 + V2) of the potential difference V1 between both ends of the first reading resistor R1 and the potential difference V2 between both ends of the second reading resistor R3, so that the potential difference V1 is Even if it decreases, the potential difference V2 increases and is compensated for, and the difference between the judgment value V when the voltage is detected with bare hands and the judgment value V'when wearing the insulating gloves becomes small.

By making the resistance value of the second reading resistor R3 sufficiently larger than the resistance value of the first reading resistor R1, the potential difference V2 between both ends of the second reading resistor R3 becomes a non-negligible size. Therefore, this voltage detector having a second reading resistor R3 and determining the presence or absence of charging by the total value (V1 + V2) of the potential differences V1 and V2 between both ends of the first and second reading resistors R1 and R3 is a bare hand. The sensitivity error between the case of voltage detection with and the case of wearing insulating gloves is small. For example, the lower limit of detection when the voltage is detected by wearing insulating gloves can be set to about 1.5 times the lower limit of detection when the voltage is detected with bare hands. That is, when the lower limit of detection of voltage detection with bare hands is about 30 V, the lower limit of detection can be set to about 45 V by wearing insulating gloves.

1 Detector 2 Circuit exposed part R1 First reading resistance R2 Protection resistance R3 Second reading resistance Rp Human resistance V Detection target (power supply)

Claims (1)

A detector that comes into contact with the AC or DC power supply to be detected,
A first read resistor R1 whose input end is connected to the detector,
The protection resistor R2 connected in series with the first read resistor R1 and
A circuit exposed portion connected to the output end of the protection resistor R2 and contacted by the human body,
It is connected to the output end of the first reading resistor R1, the output end is connected to the circuit ground, and includes a second reading resistor R3 having a resistance value larger than that of the first reading resistor R1.
It is characterized in that the presence or absence of charging of the voltage detection target is determined by the total value of the potential difference V1 between both ends of the first reading resistor R1 and the potential difference V2 between both ends of the second reading resistor R3. AC / DC voltage detector.