JPH05172443A - Power supply open-phase detecting device in refrigerating plant - Google Patents

Abstract

PURPOSE:To reduce the number of sensor means for sensing currents flowing in each of phases of a three-phase AC power supply line and also the number of signal input ports of a controller for inputting signals from the sensor means. CONSTITUTION:Each of a sum of values of currents flowing in two phases of a three-phase AC power supply and the values of a current flowing in another phase is sensed by the first and second current sensors 1 and 2, respectively. When the ratio between these current values exceeds a predetermined range, a discrimination means 32 discriminates it as an open-phase. With such an arrangement, the number of sensor means can be reduced as compared to that of the prior art device and at the same time the number of signal input ports of the controller can be reduced and its cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power source open phase detecting device for a refrigerating apparatus which is applied to a three-phase AC power source which is a power source for the refrigerating apparatus.

[0002]

2. Description of the Related Art In the conventional open-phase detection of a three-phase AC power supply of a refrigeration system, a current sensor for detecting a current value flowing through each line of R-phase, S-phase and T-phase of the three-phase AC power supply is provided. However, each current value detected by these current sensors is input to the controller, and the controller determines whether or not there is a phase loss depending on whether or not each current value is different.

[0003]

In the power supply phase loss detection in the conventional refrigeration system described above, since the current sensors are respectively provided in the three wires through which each phase current flows, the number of maintenance points is increased and the controller is Since the number of ports for inputting the signal from each current sensor is large, the cost is increased.

The present invention is intended to solve the above problems.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the gist of the present invention is to sum the current values flowing through the two phases of the above-mentioned power source in a refrigerating apparatus powered by a three-phase AC power source. A first detecting means for detecting
Second detection means for detecting the current value flowing through the phase, and when the ratio of the current value by the first detection means to the current value by the second detection means exceeds a predetermined range A power supply phase loss detecting device characterized in that it is provided with a determination means for determining a phase loss.

[0006]

In the above, the first and second current sensors detect the sum of the current values flowing in the two phases of the three-phase AC power source and the current value flowing in the other one phase, respectively, and the ratio of the current values of the two is detected. When it exceeds the predetermined range, the discriminating means discriminates that the phase is missing.

As described above, the number of detecting means can be reduced as compared with the conventional device, and the number of signal input ports of the controller provided with the discriminating means can be reduced, so that the cost can be reduced. .

[0008]

FIG. 1 shows an embodiment of the present invention. The present embodiment shown in FIG. 1 is a current transformer that is provided over the R-phase and S-phase electric wires of the three-phase AC power supply line connected to the refrigerating apparatus 10 and detects the sum of the current values of the R-phase and S-phase. And the like, and a second current sensor 2 including a current transformer or the like provided in the T-phase electric wire other than the R and S phases of the three-phase AC power supply line and configured to detect a T-phase current value. , The first and second current sensors 1,
2 inputs the current value detected respectively and calculates the ratio thereof, the calculating means 31, the setting means 33 for setting and storing a predetermined set value in advance, and the output signals of the setting means 33 and the calculating means 31 are inputted and missing. A discriminating means 32 for discriminating the presence or absence of phases is provided.

A controller 3 is formed by the arithmetic means 31, the discrimination means 32, and the setting means 33,
The two phases in which the first current sensor 1 is provided are R,
A combination of phases other than the S phase may be used.

In the above, the current value A detected by each of the first current sensor 1 and the second current sensor 2
1, A2 are input to the calculation means 31 of the controller 3,
Here, the ratio P (A1 / A2) of the current value is calculated.

The current value ratio P is input to the discriminating means 32, and the discriminating means 32 inputs and compares a preset ratio range to the setting means 33, and the current value ratio P is within this ratio range. In this case, it is determined that there is no open phase.

On the other hand, when the current value ratio P deviates from this ratio range, it is determined that the phase is open. Here, the ratio range is set to, for example, 1.5 to 2.5 in consideration of the detection accuracy of the current value and the like.

Thus, when there is no open phase, the loads of the respective phases are substantially equal, and currents of the same magnitude flow in the three wires, respectively, so that they are detected by the first current sensor 1 and the second current sensor 2. Since the ratio P of the current values is 2, which is within the ratio range, the determining unit 32 can determine that there is no open phase.

On the other hand, when there is a missing phase, for example, R phase and S phase
The current value ratio P is 1 in any one of the open phases, and the current value ratio P is in the T phase open phase.
Are excessive and exceed the respective ratio ranges, the determination means 32 can determine that there is a phase loss.

As described above, in this embodiment, the first
The presence / absence of a phase loss can be determined depending on whether or not the ratio of the current values detected by the current sensor 1 and the second current sensor 2 is within a predetermined range. 2 and the number of signal input ports of the controller 3 can be reduced.

[0016]

According to the present invention, there is provided a power source open phase detecting device for a refrigerating apparatus, wherein a sum of current values flowing in two phases of a three-phase AC power source and a current value flowing in another one phase are respectively detected as first and second current sensors. Is detected, and when the ratio of the two current values exceeds a predetermined range, the determining means determines that there is an open phase, and thus the number of detecting means can be reduced as compared with the conventional device. The number of signal input ports of the controller can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a power supply phase failure detection device according to an embodiment of the present invention.

[Explanation of reference numerals] 1 first current sensor 2 second current sensor 3 controller 31 computing means 32 discriminating means 33 setting means 10 refrigeration system

Claims (1)

[Claims] 1. A refrigeration apparatus using a three-phase AC power source as a power source, and a first detecting means for detecting a sum of current values flowing in two phases of the power source, and a current value flowing in another one phase. A second detection means for detecting, and a judgment of an open phase when the ratio of the current value by the first detection means and the current value by the second detection means exceeds a predetermined range. A power source open phase detecting device comprising means.