JPS6239304Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a clamp-type meter.

A feature of a clamp-type meter is that by sandwiching the electrical circuit to be measured between split current transformers that can be opened and closed, the current in the electrical circuit can be measured. However, clamp-type meters are generally made for relatively low voltage (600V, for example), and are not suitable for measuring high-voltage electrical circuits from a safety standpoint. On the other hand, especially in high voltage circuits,
A feed-through current transformer is installed in a switchboard or the like, and the current in the circuit is measured using an indicator, but this type of transformer cannot measure instantaneous changes in current. Therefore, when measuring high-voltage circuit current, etc., it would be possible to use an existing through-type current transformer or a measurement terminal on a switchboard, etc., and measure the current obtained from the measurement terminal with a clamp-type meter.
Extremely convenient when using clamp-type instruments. This invention was made in response to the above-mentioned demands, and embodiments of this invention will be described in detail below with reference to the accompanying drawings.

In the clamp-type meter according to this invention, as shown in the figure, a measuring device main body 1 and a clamp sensor 3 having a split current transformer 2 configured to be openable and closable are separated from each other, and the clamp sensor 3 is connected to an electric cord 4. It is designed to be connected to the measuring instrument main body 1 via. The measuring device body 1 includes a split current transformer 2.
A known amplification circuit that amplifies the current detected in the
A measuring circuit, a display circuit, etc. are built-in, and the case 5 is provided with a connection terminal 6 for the clamp sensor 3, a display 7, etc., but in this invention, a A pair of input terminals 8, 8 connected to the secondary side output terminals of an existing through-type current transformer (not shown) provided, and an energizing path 9 formed so as to be clampable by the split current transformer 2. is provided. In this case, the energizing path 9 is electrically connected to one of the input terminals 8, 8, and is attached to the case 5 in an electrically insulated state.

In the configuration described above, when the output terminals of the existing feedthrough current transformers are connected to the input terminals 8, 8 using connection cords (not shown), the secondary current of the feedthrough current transformers flows into the current carrying path 9. Therefore, by clamping this energizing path 9 with a split current transformer, the value of the current flowing therein is displayed on the display 7.
Then, by multiplying this displayed value by the winding ratio of the feedthrough current transformer and calculating backward, the measured current can be obtained.

In addition, by winding the energizing path 9 and then pulling out one or more intermediate taps and selecting that tap, coils with different numbers of turns can be obtained, thereby changing the winding ratio of the existing feedthrough current transformer. By switching the tap in accordance with the current value, it is possible to match the measured current value with the value displayed on the display 7. However, unlike the above, multiple energizing paths with different winding ratios are provided in case 5, and the energizing path having the same winding ratio as the existing feedthrough current transformer is selected and divided. The current transformer 2 may be used for clamping. In addition, the degree of amplification of the amplification circuit that amplifies the current detected by the split current transformer 2 can be changed according to the winding ratio of the existing through-type current transformer, and the current value of the current to be measured is displayed. It is also possible to match the displayed value of the device 7. Further, in this embodiment, the current conducting path 9 is specially provided, but if the handle 10 attached to the case 5 is a current conducting body, it is also possible to use the handle 10 as the current conducting path.

As is clear from the above description of the embodiment, according to this invention, the measuring instrument body and the clamp sensor are separated, and the secondary current of the existing feedthrough current transformer is passed through the measuring instrument body. By forming an electric path and clamping the current-carrying path with the clamp sensor, it is possible to also measure high-voltage target electric path current with a clamp sensor configured mainly for low voltage. Furthermore, if the main body of the measuring instrument is connected to recording instruments, this clamp-type instrument can also be used as a type of transducer, making it extremely practical.

[Brief explanation of drawings]

The figure is a perspective view of a clamp-type meter according to this invention. In the figure, 1 is the main body of the measuring device, 2 is a split current transformer, 3 is a clamp sensor, 5 is a case, 7 is a display, 8 is an input terminal, and 9 is a current conducting path.

Claims (1)

[Claims for Utility Model Registration] A clamp type comprising a measuring device main body and a clamp sensor that includes a split current transformer configured to be openable and closable and is connected to the measuring device main body via an electric cord. In the meter, the measuring device body has a pair of input terminals connected to the secondary output terminal of an existing feedthrough current transformer provided on the electrical circuit side to be measured, and an electrical connection to the input terminal. and a current-carrying path formed to be connected to the clamp sensor and clamped by the clamp sensor, and by clamping the current-carrying path with the clamp sensor, the current in the current to be measured is measured. A clamp-type instrument characterized by: