JPS6234304Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a digital measuring device that can measure high voltage by floating a common terminal, and is particularly designed to check the voltage of the battery used to drive itself with a simple configuration. It was made so that it could be done.

In general, measuring devices will give incorrect measurements if the voltage of the battery that drives the measuring device falls below a predetermined value, and if a storage battery is used, it is necessary to prevent over-discharge. , it is necessary to check the voltage of the battery used to drive itself. By the way, in order to use a digital measuring device to measure the signal voltage of a device under test whose reference potential is floating at a high voltage, for example 1000V, it is sufficient to float the entire digital measuring device. In this case, as long as the battery that drives the digital measuring device is also floating, there is no problem in measuring the driving battery voltage with this digital measuring device. However, when multiple measurement devices are commonly driven by a single battery, and one measurement device and the other measurement device measure devices under test with different reference potentials, there is a problem in deciding what to do with the reference potential of the drive battery. arise. For example, when driving an oscilloscope and a floating digital measurement device with a single battery, the input terminal of the oscilloscope consists of a signal section and a ground section, and this ground section is connected to the chassis of the oscilloscope. In order to protect the oscilloscope and the safety of the operator, it is necessary to ground the reference potential of the drive battery and isolate the drive battery from the digital measuring device. In such a case, if you connect the measuring terminal of the digital measuring device to the drive battery while applying a high voltage to the floating terminal of the digital measuring device, the high voltage between the floating terminal and the driving battery will be directly supplied to the digital measuring device. The digital measuring device is destroyed. Therefore, in order to measure the voltage of the drive battery using the digital measuring device itself,
There must be complete isolation between the digital measuring device and the device under test. Further, although other voltage measuring devices may be used, it is not possible to easily check the drive battery voltage during measurement.

In view of this, the present invention is designed to allow the voltage of the battery used for self-driving to be arbitrarily checked with a simple configuration without the need for a special battery voltage checking device.

An embodiment of the digital measuring device of the present invention will be described below with reference to FIG.

In FIG. 1, 1 indicates a battery, and this battery 1
The negative electrode of the battery 1 is grounded, and the positive electrode of the battery 1 is connected to the power terminal of the oscillator 2. In this case, the level of the oscillation output signal of this oscillator 2 is proportional to the voltage of the battery 1.
The oscillation output signal of this oscillator 2 is supplied to a primary winding 3a of a transformer 3 constituting an isolation device.

Note that the oscillator 2 is also connected to the feedback winding of the transformer 3.

In this example, the secondary winding 3b of this transformer 3
The middle point of the secondary winding 3b is connected to a floating terminal which is a common terminal, and one end of this secondary winding 3b is connected to the input side of a stabilized power supply circuit 5 via a rectifier circuit 4 for obtaining a positive DC voltage. The positive DC voltage obtained on the output side of the stabilized power supply circuit 5 is supplied as a positive power source to a digital measuring section 6 configured to be able to measure, for example, DC voltage values, AC voltage values, current values, resistance values, etc. , and the other end of this secondary winding 3b is connected to the input side of a stabilized power supply circuit 8 via a rectifier circuit 7 for obtaining a negative DC voltage, so that a negative DC voltage can be obtained at the output side of the stabilized power supply circuit 8. A negative DC voltage is supplied to the digital measuring section 6 as a negative electrode. Reference numeral 9 indicates a measurement terminal to which a desired measurement input signal is supplied, one ground side of this measurement terminal 9 is connected to a floating terminal, and the other side of this measurement terminal 9 is used for switching the measurement input signal and battery voltage measurement. The movable contact 10 of this switch 10 is connected to one fixed contact 10S of the switch 10.
A is connected to the input side of the digital measuring section 6, and the measurement result in the digital measuring section 6 is supplied as a display signal to a display device 11 consisting of an LED. Rectifier circuits 4, 7, stabilized power supply circuit 5, etc.
8. The digital measuring section 6 and the display device 11 are configured to float as in the prior art, and to be able to measure signals floating at a high voltage as in the prior art.

In this example, one end of the secondary winding 3b of the transformer 3 is connected to the input side of a rectifier circuit 12 that obtains a negative DC voltage, and the negative DC voltage obtained at the output side of the rectifier circuit 12 is connected to a comparison circuit. 13, and the output side of this rectifier circuit 12 is connected to a floating terminal via a series circuit (voltage dividing circuit) of two resistors 14 and 15.
4 and 15 are connected to the other fixed contact 10B of the switch 10. Further, the output side of the stabilized power supply circuit 8 is connected to the other input terminal of the comparator circuit 13, and the output side of the stabilized power supply circuit 8 is connected to the resistor 16.
is connected to the connection point of resistors 14 and 15 through. In this comparator circuit 13, when the difference between the voltages supplied to one and the other input terminals exceeds a predetermined value, that is, the voltage drop across the resistors 14 and 16 exceeds a predetermined value, the output of this comparator circuit 13 An alarm signal is obtained from the side, and this alarm signal is supplied to the display device 11 to display an alarm display, for example, "LO", "...". In addition, in order to compensate for the voltage drop of the diode of the rectifier circuit 12, the resistor 16 causes a compensation current to flow through the resistor 15 so that the voltage at the connection point of the resistors 14 and 15 is accurately proportional to the voltage of the battery 1. There is.

Since this example is configured as described above, when used as a digital measuring device, the movable contact 10a of the switch 10 is connected to one fixed contact 10S,
A measurement input signal from the measurement terminal 9 is supplied to the digital measurement section 6, and desired measurements can be performed in the same manner as in the conventional method. At this time, an AC voltage at a level corresponding to the voltage of the battery 1 is obtained at one end and the other end of the transformer 3, and a DC voltage proportional to the voltage of the battery 1 is obtained at the output side of the rectifier circuit 12, but it is not stable. Since a constant DC voltage is obtained on the output side of the rectifier circuit 8 until the output side of the rectifier circuit 7 becomes below a predetermined value,
When the voltage of the battery 1 drops to a certain value, an alarm signal is obtained at the output side of the comparator circuit 13, and this is displayed on the display device 11, so that it is known that the voltage of the battery 1 has fallen below a certain value. Can be done.

Next, when measuring the voltage of battery 1, switch 10
The movable contact 10a is connected to the other fixed contact 10B, and a voltage proportional to the voltage of the battery 1 obtained at the connection point of the resistors 14 and 15 is supplied to the digital measuring section 6. In this case, since the output voltages of the stabilized power supply circuits 5 and 8 are still constant at the beginning when the above-mentioned alarm signal is obtained, it is possible to accurately measure the voltage of the battery 1. In this case, to measure the voltage of battery 1, floating 2 of transformer 3 is used.
Since the measurement signal is obtained from the next side, measurements can be made without any inconvenience even if the floating terminal is connected to a high voltage.

As described above, according to the present invention, the primary winding 3a of the transformer 3 is driven by the oscillator 2 whose power source is the battery 1 whose one electrode is grounded, and the secondary winding 3a of the transformer 3 is driven by the voltage on the secondary side of the transformer 3. When measuring the voltage of the battery 1 using the floating digital measuring section 6, the measurement signal is obtained from the secondary side of the floating transformer 3, so there is no problem in using the own digital measuring section 6. There is a measurable benefit.

2 and 3 show other embodiments of the present invention, respectively. In FIGS. 2 and 3, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In the example in Figure 2, a tertiary winding 3 for measuring the voltage of the battery 1 is connected to the secondary side of the transformer 3 in the example in Figure 1.
c. That is, in the example shown in FIG. 2, one end of the tertiary winding 3c of the transformer 3 is connected to a floating terminal, and the other end of the tertiary winding 3c is connected through a rectifier circuit 12 that obtains a negative DC voltage. It is connected to the other fixed contact 10B of the switching device 10 and also to one input terminal of the comparison circuit 13, and is otherwise constructed in the same manner as in FIG. In FIG. 2, an AC voltage at a level corresponding to the voltage of the battery 1 is obtained between both ends of the tertiary winding 3c, so it is easy to understand that the same effect as in FIG. 1 can be obtained. Good morning.

In addition, the example in Figure 3 has a tertiary winding 3 on the secondary side of the transformer 3.
c, one end of this tertiary winding 3c is connected to a floating terminal, the other end of this tertiary winding 3c is directly connected to the other fixed contact 10B of the switching device 10,
The other components are constructed in the same manner as in FIG. 1, and this tertiary winding 3c
The digital measurement unit 6 measures the AC voltage at a level corresponding to the voltage of the battery 1 obtained at the time.

It is easy to understand that the example shown in FIG. 3 has the same effect as the example shown in FIG.

It goes without saying that the present invention is not limited to the above-described embodiments, and that various other configurations may be adopted without departing from the gist of the present invention.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the digital measuring device of the present invention, and FIGS. 2 and 3 are block diagrams showing other embodiments of the present invention. 1 is a battery, 2 is an oscillator, 3 is a transformer, 4, 7
and 12 are rectifier circuits, 5 and 8 are stabilized power supply circuits, 6 is a digital measurement section, 9 is a measurement terminal,
10 is a switching device, and 11 is a display device.

Claims (1)

[Scope of utility model registration request] a transformer with a floating secondary side, a battery with one electrode grounded, and an oscillator that uses the battery as a power source to drive the primary winding of the transformer;
a floating digital measurement section that is driven by the voltage from the secondary side of the transformer and has at least a voltage measurement function; A digital measuring device characterized in that it is equipped with a changeover switch that supplies power to the user.