JPS5818445Y2 - Open phase display device - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an open phase display device in a three-phase power supply.

Conventionally, there have been devices for detecting phase loss when it occurs and protecting control equipment, but they are complicated.

There were also overload relays that could be used for this purpose.

In the conventional equipment, a single neon lamp was simply provided between the two (RT) phases of the Sanwa Chuo T2 (RT) to indicate whether the power supply was on or off, as shown in FIG.

For this reason, for example, if there is an open phase in the S phase, the motor's overload relay will operate even though the neon lamp is on, so you will not be aware of the open phase and will not be able to find the cause. I often had to look elsewhere for repairs.

This has been often pointed out in agricultural dryers, etc., which are operated by housewives of farmers.

Therefore, in view of the conventional situation, this invention attempts to provide an open phase display device that can easily detect the presence or absence of an open phase by simply changing the conventional configuration.

The content of this invention will be explained below based on the drawings.

As shown in Fig. 2A, a neon lamp WNI having equal impedance between the R phase, other T phases, and S phases
, WN2 are connected, and a resistor R is connected in parallel (between the RT phases) with the neon lamp WN1, which is one of these neon lamps.

The magnitude of the resistance R is the neon lamp WN in parallel.
It is regulated as follows in relation to the absolute value of the impedance of I.

(Z indicates the impedance of the neon lamp WNI.

) Now, if the R phase is open, the circuit configuration shown in Figure 2 will be created, and the voltage applied to the neon lamp WN1 will be the same as that of the indicator lamp WN.
The neon lamp WN2 is lit, but the neon lamp WNI is not lit.

If there is no resistor R at this time, both neon lamps WNI
, WN2 are applied with divided voltages, and both of them light up slightly, making it unclear as an open phase indication.

Further, when the S phase is open, only the neon lamp WNI is lit, and when the T phase is open, only the neon lamp WN2 is lit.

(If the relationship between the resistance R and the impedance of the neon lamp is outside the above-mentioned regulation range, discrimination is possible, but the brightness of the neon lamp decreases, making discrimination difficult.

) This means that when an open phase occurs, one of the two neon lamps will always go out, making it possible to accurately indicate the open phase, making it easier to discover the cause of the failure and repair it. .

Note that when the transformer TR is connected to the RT phase as shown in FIG. 3, the impedance on the negative side has the same effect as the resistor R, so there is no need to provide the resistor R.

[Brief explanation of the drawing]

FIG. 1 shows a conventional configuration, FIG. 2 shows an embodiment of this invention, and FIG. 3 is a circuit diagram showing another embodiment of this invention.

Claims (1)

[Claims for Utility Model Registration] A neon lamp WNI between one phase R of the three-phase power supply R, S, and T and the other two phases S and T, respectively. WN2 is connected, and a resistor R is connected in parallel with one of these neon lamps WNI, and the value of the resistor R is such that the voltage applied to the neon lamp WN1 is discharged when the negative phase R is open. 1. An open phase display device characterized by being set to limit the voltage to below a starting voltage.