JPH04106348A - Device for limiting input current of air conditioner - Google Patents

Abstract

PURPOSE:To prevent a power failure by the operation of a circuit breaker by a method wherein, when a first-detection value of current has exceeded the limit, the limit to the input current of the air conditioner is decreased by value corresponding to the excess and the frequency output to the compressor is adjusted by a frequency- converting circuit. CONSTITUTION:A limiting current-value IM to the total input current I, which conforms to the contract demand for interior wiring, is preliminarily set in a circuit breaker 1 and in a controlling microcomputer 4 for the air conditioner this current-value IM and an input current-limiting value IN applicable to the air conditioner in its ordinary operating condition are set. The controlling microcomputer 4 for the air conditioner reads in the total input current I detected by a first current detection circuit 2 and compares it with the limiting current-value IM; if the total input current I exceeds the limiting current-value IM, by stepwise decreasing the input current-limiting value IN of the air conditioner by a value corresponding to the difference, the output frequency is lowered and sent to a frequency-covering circuit 5 and the compressor 6 is run with a lowered capacity; and with the input current to the compressor 6 depressed, and the total input current, when other electric appliances are turned on, increases but to a lowered value. Thus the circuit breaker 1 can be restrained from actuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air conditioner that is supplied with power via a breaker in indoor wiring, and specifically relates to an input current limiting device for an air conditioner.

[Conventional technology]

Conventionally, when power is supplied to an air conditioner along with other electrical equipment from the household power distribution line, other electrical equipment may be turned on while the air conditioner is operating, exceeding the contracted power amount, causing the breaker to trip. Accidents that cause air conditioners to stop operating frequently occur.

In this condition, if you disconnect other electrical equipment and immediately turn on the breaker again, the compressor may not start due to pressure imbalance in the refrigerant circuit of the air conditioner, which often leads to accidents such as the compressor not starting or shutting down. ing.

For this reason, air conditioners are equipped with a power select switch that limits the input current, and in usage conditions close to the contracted power amount, it is set to "power save (low input current)" and the input current of the air conditioner is set to "power save (low input current)". The air conditioner is operated with reduced capacity to prevent the breaker from tripping, and the power select switch is returned to normal operation after all other electrical equipment is used.

During this time, not only will the capacity of the air conditioner decrease, causing problems such as cooling or heating not working, but also problems such as forgetting to switch the power select switch because the power select switch is manual even after using other electrical equipment. Problems remain.

[Problem to be solved by the invention]

The present invention was made in view of the above-mentioned conventional problems, and when power is being supplied to an air conditioner along with other electrical equipment from the household power distribution line, the contracted power amount can be reduced by turning on the other electrical equipment. An air conditioner that prevents power outages due to breaker activation by detecting an increase in total input current and reducing the air conditioner input current to a range that does not interfere with operation. is intended to provide.

[Means to solve the problem]

In order to achieve the above object, a first current detection circuit for detecting the total input current is provided at the input end of the breaker, and a second current detection circuit for detecting the input current is provided at the input side of the air conditioner. The control microcomputer receives the first detection value of the first current detection circuit and compares it with the current limit value of the breaker. The input current limit value of the conditioner was lowered, and the frequency output to the compressor was controlled by a frequency conversion circuit so that the input current of the air conditioner was below the input current limit value.

[Function] According to the above configuration, a first current detection circuit that detects the total input current from the input side of the indoor wiring breaker and a second current detection circuit that detects the input current of the air conditioner are provided, The first detected value by the first current detection circuit is compared with the limit current value of the breaker, and if the first detected value exceeds the limit current value, the difference is calculated by the second detection value of the second current detection circuit. By subtracting it from the value to obtain the input current limit value of the air conditioner, keeping the input current of the air conditioner low to the input current limit value, and ensuring that the total input current does not exceed the limit current value of the breaker, By operating the breaker, it is possible to prevent accidents such as unexpected power outages and the inability to restart the compressor.

〔Example〕

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of the present invention, which includes a first current detection circuit 2 that detects the total input current on the input side of a breaker 1 installed on the entrance side of indoor wiring, and a first current detection circuit 2 on the output side of the breaker 1. A rectifier circuit 3 of the air conditioner connected to the air conditioner supplies power to a control microcomputer 4 and a frequency conversion circuit 5 to drive a compressor 6.

A second current detection circuit 7 for detecting the input current of the air conditioner is provided on the inlet side of the rectifier circuit 3 to monitor the input current of the air conditioner and send it to the control microcomputer 4 for input. The input current limit value is set in stages to match the current value.

The control microcomputer 4 compares the set input current limit value with the second detection value detected by the second current detection circuit 7 and sends a frequency output lowered by the difference to the frequency conversion circuit 5. , controls the operation of the compressor 60.

The breaker 1 is preset with a limit current value In for the total input current I that corresponds to the contracted power amount for indoor wiring, and the air conditioner control microcomputer 4 sets the limit current value ■A to normal operation. Set the air conditioner's input current limit value ■8 in the current state.

The total input current I detected by the first current detection circuit 2 is taken into the control microcomputer 4 of the air conditioner, and the control microcomputer 4 compares the total input current I with the limit current value A. (If it exceeds 11M, the output frequency is lowered by lowering the input current limit value IN of the air conditioner step by step by the difference and sent to the frequency conversion circuit 5, the compressor 6 is operated in a low capacity state, and the compressor By suppressing the input current of 816, the increase in total input current is reduced when other electrical equipment is turned on, and the operation of breaker 1 is suppressed.

FIG. 2 is a flowchart showing the details of the present invention, in which the control microcomputer 4 is preset with the limit current value (■) of the total input current I of the breaker 1. and the input current limit value Is of the air conditioner 21), and the first current detection circuit 2 determines the total input current I
is detected and sent to the control microcomputer 4 (22), and the difference DI between the total input current I and the limit current 41LTM is detected.
3) If the total input current I exceeds the limit current value IN (
If DI is positive) (24), set the limit current setting value lowered by the difference DI to 4 to generate a frequency output (25)
, by operating the compressor 6, the total input current I becomes the limit current value of the breaker 1 ■. You can drive within a range that does not exceed.

Of course, if DI is not positive, the current release setting value IA becomes the input current limit value Is in the normal operating state (2
6).

As described above, when the total input current I passing through the breaker 1 exceeds the limit current value ■4 of the breaker 1, the limit current setting value ■ of the air conditioner is set to be lowered by the increase in the total input current ■. As a result, the compressor 6 is operated in a low capacity state to lower the input current of the air conditioner, suppressing an increase in the total input current,
Breaker 1 due to increase in input current when using other electrical equipment
operation can be suppressed.

〔Effect of the invention〕

As described above, in the present invention, the total input current exceeds the limit current value of the breaker in order to prevent an accident in which the total input current temporarily increases and the breaker trips due to the turning on of electrical equipment connected to the same breaker. In some cases, by lowering the input current of the air conditioner and suppressing the increase in the total input current, the breaker is suppressed from operating, thereby preventing accidents such as unexpected power outage due to the breaker tripping and the inability to restart the air conditioner. can do.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a flow chart showing details of the invention. In the figure, 1 is a breaker, 2 is a first current detection circuit, 3 is a rectifier circuit, 4 is a control microcomputer, 5 is a frequency conversion circuit, 6
is a compressor, and 7 is a second current detection circuit. Patent applicant: Fujitsu General Ltd. Figure 1 Figure 2

Claims (1)

[Claims] In an air conditioner that is equipped with a control microcomputer and a frequency conversion circuit that performs variable capacity control of the compressor, and is supplied with power from indoor wiring via a breaker, there is a first controller on the input side of the breaker that detects the total input current. A second current detection circuit for detecting an input current is provided on the input side of the air conditioner, and the control microcomputer receives the first detection value of the first current detection circuit and controls the breaker. When compared with the limiting current value, when the first detected value exceeds the limiting current value,
The input current limit value of the air conditioner is lowered by the amount exceeding the input current limit value, and the frequency output to the compressor is controlled by a frequency conversion circuit so that the input current of the air conditioner is equal to or less than the input current limit value. Input current limiting device for air conditioners.