JPH08310U - AC meter - Google Patents

Abstract

(57) [Abstract] [Purpose] When the general public measures the current consumption of home appliances,
Just plug in the plug of the household appliances,
An object of the present invention is to provide an AC power meter which can be safely measured without worrying about electric shock and has a simple structure. [Structure] When measuring a low current, connect a load to the first measurement terminal, boost the voltage drop of three series resistors, and rectify the voltage.
Read the shake of the data. When measuring a high current, a load is connected to the third measuring end, and the load current flows only to the input side resistance of the three series resistors. Therefore, the voltage drop due to this load current is boosted and rectified. -Read the shake of the data. In addition,
The two resistors, through which the load current does not flow, are connected in series to the input impedance of the booster as a circuit, but they can be ignored as compared with the input impedance of the booster. There is no problematic error in the current value.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an AC meter (AC ammeter or AC power meter) for measuring the current used in home appliances and the like by appropriately selecting the measurement end according to the weight of the load and inserting the plug of the household appliance into the outlet.

[0002]

[Prior art]

 Conventionally, a clamp type AC ammeter is used in the case of a two-wire type power supply. With this AC current meter, only one of the two-wire power supply lines is clamped for measurement. When measuring, switch the measurement range appropriately according to the current value. However, when measuring the current consumption of home electric appliances by this measurement method, preparatory work as shown in Fig. 5 is required. That is, the input power source side and the home electric appliance side must be connected by two single wires. Then, one of the two single wires is clamped and measured.

Further, there is a method of measuring using a tester that is widely used. However, since a general tester cannot measure a large current such as the current consumption of home appliances, as shown in Fig. 6, the same situation as when measuring with a clamp type AC ammeter is used. Preparatory work is required. That is, two single wires are wired to each other, and a resistor 6 is connected in series in the middle of one of them. Then, the voltage value dropped by the current flowing through the resistor 6 is divided by the value of the resistor 6 to calculate the consumed current.

[0004]

[Problems to be solved by the device]

 The clamp-type AC ammeter in the conventional measurement method is expensive because it requires the preparatory work that involves the danger of electric shock for ordinary people, and is used by electricians for business purposes. However, there was a problem that it was not always available in ordinary households. In addition, the measurement method using a tester requires the dangerous preparations similar to the above, and there is also the inconvenience that large and small resistances must be prepared according to the current value to be measured. It was

In view of this problem, an object of the present invention is to provide an AC ammeter or an AC wattmeter, which enables even a general person to easily measure a wide range of consumption current (that is, AC current) of home electric appliances and the like. And

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is provided with N measuring terminals formed as a pair of two terminals, and one terminal of the AC power input terminal is connected to the first to Nth measuring terminals. Wire to each of the terminals up to the measuring end, connect N resistors in series to the other terminal of the input end, and connect the terminal resistance to the other terminal of the first measuring end, Each of the N-1 connection points of is connected to the other terminal from the second measurement end to the Nth measurement end, and one of the N output ends is connected to one of the measurement ends. When a load is applied to the resistor, the voltage dropped by the current flowing through the resistor is boosted by the booster, the boosted AC voltage is rectified by the rectifier, and the rectified DC current is converted to the direct current ammeter through the adjustment resistor. The AC measurement value is supplied and the AC measurement value is known from the DC current value flowing through the DC ammeter.

[0007]

[Action]

 When measuring a low current, a load is connected to the first measuring end, the voltage drop of three series resistors is boosted, rectified and the deflection of the meter is read. When measuring a high current, connect a load to the third measurement terminal, and the load current flows only to the input side resistance of the three series resistors. Therefore, the voltage drop due to this load current is boosted to rectify the current. Read the shake of the meter.

The two resistors through which the load current does not flow are connected in series with the input impedance of the booster in a circuit, but have a value that can be ignored in comparison with the input impedance of the booster. Therefore, there is no problematic error in the read measurement value.

[0009]

【Example】

 1 to 4 are block diagrams showing an embodiment of the present invention. The common parts in the figure are given the same reference numerals.

First, FIG. 1 will be described.

Input power is input to terminals A and B, and when the load is low, the load is connected to the first measurement end. That is, the output terminal A1 and the output terminal B1 are connected. The voltage drop caused by the load current flowing through the series resistors R1, R2 and R3 is amplified by the voltage amplifier 1, rectified by the rectifier 2, and measured by the DC ammeter 3 through the adjusting resistor R4.

When the load is heavy, the second measuring end or the third measuring end is used in accordance with the load current. For example, when the third measuring end is used, the resistance R1 As a result, the voltage drop caused by the load current flowing in the circuit is measured. The adjustment resistor R4 is used to calibrate the DC ammeter 3.

In this case, the resistors R2 and R3 are connected in series with the input impedance of the voltage amplifier 1. Here, the issue is whether these two resistors do not cause an error in the measured value.

Therefore, the magnitude of each resistance value will be described using a specific example. The description will be given on the assumption that a non-linear rectifier having only a diode with bad conditions is used rather than a linear rectifier combining an IC and a diode.

In order to improve the measurement accuracy, if a 30% or more full scale value of the DC ammeter 3 is operated in the linear portion of the rectifier 2, the input voltage of the rectifier 2, that is, the voltage amplifier 1 The output voltage is usually about 1 volt when the pointer is 30 percent, and in that case it is about 3.3 volts when the pointer is 100 percent. Assuming that the voltage amplification degree of the voltage amplifier 1 is 100 times, the input voltage of the voltage amplifier 1 becomes about 0.033 volt when the 100 percent value pointer is set.

For example, if a load having an input voltage of 100 V and a maximum power consumption of 1.5 kW is connected to the third measuring end, the current flowing through R1 is 15 amperes, and the resistance of the terminal resistance R1 is The value is about 0.0022 ohm. Next, regarding R2, if the maximum measured power at the second measurement end is 600 watts, the calculation result is about 0.0033 ohms. Finally, regarding R3, if the maximum measured power at the first measuring end is 150 watts, it will be about 0.022 ohms.

It is economical to realize such low resistance as R1, R2 and R3 by using a nichrome wire. However, the length of the nichrome wire needs to be more accurately determined in order to achieve the predetermined resistance value. One way to do this is to fix the nichrome wire in point contact with an electrical conductor.

As described above, R1. R2. The resistance value of R3 is very small and negligibly small compared to the input impedance of the voltage amplifier 1, and the problem that the measurement value has an error is not practical. In addition, the voltage drop due to the above-mentioned resistance (maximum about 0.033 volt) is also small, and it hardly affects the operating voltage of the load. In FIG. 1, the DC ammeter 3 uses a general tens of microampere class. In this case, if a heavy load is accidentally connected to the first measurement end that measures low load, one of the methods to protect the meter is to install an amplitude limiter on the output side of the voltage amplifier 1 or rectifier 2. Limit the amplitude provided. The level to be limited is determined in consideration of the measurement error on the full scale side of the meter and the strength of the pointer and the drive mechanism of the meter. The approximate limit level is set to about 140 percent of full scale when a heavy load is connected to the first measuring end.

FIG. 2 shows a configuration in which the power source of the voltage amplifier 1 is obtained from the input power instead of the battery 4 shown in FIG. Since this circuit is generally used, its explanation is omitted. In FIG. 3, instead of the voltage amplifier 1 shown in FIG. 1 or 2, the voltage is boosted by a boosting transformer 4.

FIG. 4 shows a case where there are two measurement ends. The feature is that the output terminal B1 and the output terminal B2 are shared. As described above, the AC meter of the present invention is used not only as an AC ammeter but also when the scale of the DC ammeter 3 (that is, the scale) is converted into electric power when used in a 100-volt system or a 200-volt system. Therefore, it can be used as an AC wattmeter and, like the AC voltmeter, is within the scope of the invention registration.

[0021]

[Effect of device]

 As described above, in the present invention, the N resistors are connected in series and the voltage drop thereof is devised so that a single measuring circuit can easily configure a plurality of measuring terminals. Also, if the present invention is configured using a general outlet, even an ordinary person can simply plug the plug into the outlet and safely measure the current consumption and power consumption of home appliances without worrying about electric shock. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention when a voltage amplifier is used as a booster.

FIG. 2 is a block diagram when the voltage amplifier power supply is changed to another means in FIG.

FIG. 3 is a block diagram of another embodiment of the present invention when a step-up transformer is used as a step-up means.

FIG. 4 is a block diagram of an embodiment of the present invention in which a terminal at a measuring end is shared.

FIG. 5 is a diagram showing a method of measuring with a clamp type AC ammeter, which is a conventional example.

FIG. 6 is a diagram showing a method of measuring with a general tester, which is a conventional example.

[Explanation of symbols]

 1 Voltage Amplifier 2 Rectifier 3 DC Ammeter 4 Step-up Transformer 5 Clamp Type AC Ammeter 6 Tester R1 to R3 Series Resistance R4 Adjustment Resistance R5 Resistance R6 Resistance C1, C2 Capacitor D1 Diode D2 Constant Voltage Diode

Claims (2)

[Scope of utility model registration request] 1. A two-wire type AC meter having N measuring terminals (N is an integer of 2 or more) formed with two terminals as a pair, wherein one terminal of an input terminal of AC power is a first terminal. Wiring to each of the terminals from one measuring end to the Nth measuring end, and connecting N resistors in series to the other terminal of the input end,
A terminal resistance is wired to the other terminal of the first measuring end, and each of the N-1 connection points of the series resistance is connected to the other terminal from the second measuring end to the Nth measuring end. The voltage dropped by the current flowing through the resistor when a load is applied to any one of the N output terminals by wiring is boosted by the booster, and the boosted AC voltage is rectified by the rectifier, An alternating current instrument characterized in that a rectified direct current is supplied to a direct current ammeter via an adjusting resistor, and an alternating current measured value is known from a value of a direct current flowing through the direct current ammeter. 2. N is 2, and the terminal of the first measuring end and the terminal of the second measuring end which are directly wired from the input end are commonly used as one terminal. The AC meter according to claim 1.