JPH0723523A - Failure detector for surge preventive circuit - Google Patents

Abstract

PURPOSE:To protect a surge current preventive resistor against burning by allowing detection of failure in the relay of a surge preventive circuit. CONSTITUTION:The failure detector for surge preventive circuit comprises a series circuit of a resistor R2 and a photocoupler 18 connected in parallel with a relay RY and a surge current preventive resistor R1, a comparator 20, and an alarm means 22. Upon failure of the relay RY, abnormality is detected by the photocoupler 18 and an alarm is delivered. At the same time, a load drive means 16 is turned OFF thus protecting the surge current preventive resistor R1 against burning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detection device for an inrush prevention circuit for preventing inrush current when power is turned on.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional commercial power source smoothed by D
A general circuit for controlling the load is shown as C current. Figure 1
In the figure, 10 is a rectifier, 12 is a load, a broken line portion 14 is an inrush current prevention circuit when the power is turned on, C is a capacitor,
RY is a relay, R is a resistor, and F is a time lag fuse.

When the power is turned on, the relay RY does not turn on and the resistor R
The capacitor C is charged via the. After sufficiently charging C, RY is turned on to shift to energization control.

Under normal circumstances, if RY fails, the load current continues to flow via R. R is originally for operation only at the time of rushing in, and will burn if the same power as the load is applied. In order to prevent this, as shown in FIG.
A fuse F is inserted in series with and the fuse F is cut to prevent the burnout of R.

[0005]

However, in the above-mentioned conventional technique, the fuse F is blown to protect the resistor R from being burned out. However, the fuse F is rated up to 250 V AC and is compatible with a voltage higher than that. There is a problem that you cannot do it.

Further, the time until the fuse F is blown is the resistance R
Since a load current flows through the resistor R, stress is applied to the resistor R. Since the fuse can be replaced, it is possible to operate until the fuse is replaced and blown again without solving the cause of the blown fuse, and there is also a problem that the resistor R is eventually burned out. .

Further, in the protection by blowing the fuse, the power is suddenly cut off and the power cannot be turned on again.
There is also a problem that it is difficult to identify the cause.

The present invention has been made to solve the above-mentioned conventional problems, and is a failure detection device for an inrush prevention circuit capable of detecting a failure of the inrush prevention circuit and preventing fuel loss of the inrush current prevention resistor. The purpose is to provide.

[0009]

SUMMARY OF THE INVENTION The present invention comprises means for detecting a failure of a relay of an inrush current prevention circuit when power is turned on or a switch element or the like in place of the relay, and means for issuing an alarm when the failure is detected. When a failure of the inrush current prevention circuit is detected, the load driving means or the power switch is turned off to prevent the inrush prevention resistor from burning.
The above object is achieved.

The present invention also provides a means for detecting the above-mentioned failure.
When a failure of the inrush current prevention circuit is detected, an alarm is issued,
By turning off the load driving means or the power switch, the above-mentioned object is achieved in the same manner.

[0011]

According to the present invention, failure detection means is provided in the inrush current prevention circuit and the current flowing through the inrush current prevention resistor is detected to detect the failure of the relay of the inrush current prevention circuit or the switch element or the like in place of it. However, when a failure is detected, the load driving means is turned off to prevent the rush current prevention resistor from burning.

Further, since the alarm means reports that there is a failure, the failure location and the cause can be easily specified.

[0013]

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

FIG. 2 is a circuit diagram showing a schematic configuration of a failure detection device for the inrush prevention circuit according to this embodiment.

In FIG. 2, 10 is a rectifier, 12 is a load, 16 is a load driving means, 18 is a photocoupler, 20 is a comparator, and 22 is an alarm means. As shown in FIG. 2, there is an inrush current prevention resistor R _{1 in} parallel with the relay RY,
Further, separately from this, a resistor R ₂ and a photocoupler 1 are connected in parallel.
8 is connected.

The operation of this embodiment will be described below.

As shown in FIG. 3, when the power is turned on, the relay is
RY is OFF, resistance R ₁Through the current i₁
Flow C is charged. As explained later, this
When OCL (excess current) flows, reset (RE
During S), normal inrush current prevention operation is performed without detecting any abnormality.
U

Under normal conditions, when C is fully charged, relay R
Y is turned on and energization control is performed.

When the relay is out of order, the relay RY is turned off.
When the load 12 is driven while the current is flowing, a current i ₁ having a waveform as shown in FIG. 3 or particularly enlarged in FIG. 4 flows.
i ₁ flows to the load 12 via the resistor R ₁ and is consumed.
At this time, the voltage i across the resistor R ₁ as shown in FIG.
₁ × R ₁ is a light emitting diode 18A of the photocoupler 18.
Is larger than the forward voltage V _{F of the} photocoupler 18,
Current i ₂ = as shown in FIG. 6 _{(i 1 × R 1 -V F} ) /
R ₂ flows. Then, the output phototransistor 18B of the photocoupler 18 is turned on, and the comparator (COM
The output of P) 20 is as shown in FIG. 7, and as shown in FIG. 3, an abnormality is detected, the alarm means 22 is activated, and the load driving means 16 is turned off.

FIG. 8 is a flowchart showing the abnormality detecting operation. When the OCL output from the comparator 20 is detected in step 100 of FIG. 8, step 110
During resetting (when power is turned on), no abnormality is detected,
If not resetting, the process proceeds to step 120, the alarm means 22 is activated to issue an alarm, and the load driving means 16 is turned off.
To As a result, the failure of the relay RY is notified and the rush current prevention resistor R ₁ is prevented from burning.

Alternatively, instead of turning off the load driving means 16, the main power switch may be turned off. At this time, the alarm means 22 is activated and then the power is turned off.

[0022]

As described above, according to the present invention, the fuse is normally up to 250 V, but the failure of the relay of the inrush current prevention circuit can be detected without being affected by the power supply voltage, and the inrush current prevention resistor can be found. It has an excellent effect that it is possible to prevent the burnout and the failure can be limited by the alarm means.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an outline of a conventional inrush prevention circuit.

FIG. 2 is a circuit diagram showing an outline of a failure detection device for an inrush prevention circuit according to the present embodiment.

FIG. 3 is a timing chart showing the operation of the failure detection device for the inrush prevention circuit according to the present embodiment.

FIG. 4 is a diagram showing a waveform of a current i ₁ flowing through an inrush current prevention resistor R ₁ when a load is driven when the relay is OFF.

5 is a diagram showing the voltage across the resistor R _{1 with} respect to the current of FIG.

FIG. 6 is a diagram showing a current flowing through the photocoupler at the time of abnormality.

FIG. 7 is a diagram showing a comparator output when an abnormality is detected.

FIG. 8 is a flowchart showing the operation of abnormality detection.

[Explanation of symbols]

 10 ... Rectifier 12 ... Load 14 ... Inrush prevention circuit 16 ... Load driving means 18 ... Photo coupler 20 ... Comparator 22 ... Warning means

Claims (2)

[Claims] 1. A failure of an inrush current prevention circuit, comprising means for detecting a failure of a relay of the inrush current prevention circuit when power is turned on or a switch element or the like in place of the relay, and means for issuing an alarm when the failure is detected. When the above is detected, the load detection means or the power switch is turned off to prevent the inrush prevention resistor from being burnt out. 2. The inrush according to claim 1, wherein when the failure detecting means detects a failure of the inrush current prevention circuit, an alarm is issued and the load driving means or the power switch is turned off. Failure detection device for prevention circuit.