JP2000163139A - Tap switching type power saving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tap switching type power saving device for executing an effective power saving operation without preliminarily setting any waiting time, and without needing the frequent switching of a tap. SOLUTION: This device is provided with plural waiting time timers 6 for counting a time limit for switching a transformer tap 1 from a direct transmitting state to a power saving state when an input voltage is restored from a normal voltage Vt or less to a normal voltage, plural lapse time timers 7 for counting the lapse time since the power saving stage is restored, and a timer selecting circuit 5 for selecting the timer. Then, when the fluctuating interval of the input voltage is short, the switching waiting time of the tap is lengthened, and otherwise, the switching waiting time of the tap is shortened by a central control circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power-saving device using a tap-switching transformer capable of switching between direct transmission and, more particularly, to a tap-switching power-saving device having an improved switching operation.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a control circuit of a conventional power saving device utilizing tap switching of a transformer, and FIGS. 6 and 7 show how the operation thereof changes over time. In FIG. 5, 15 is a tap switching unit of a transformer, 16 is a tap switching circuit, 17 is a control circuit, 18 is a timer circuit, 19 is a voltage detection circuit for detecting a primary voltage or a secondary voltage of the transformer. is there.

In the conventional tap-switching type power saving device, while the input voltage is monitored by the voltage detecting circuit 19, when the detected voltage becomes equal to or lower than a specified voltage serving as a reference for switching, the control circuit 17 directly sends the transformer tap 15 to the transformer tap 15. Tap switching circuit 1
6, the input voltage is output as it is without passing through the transformer, and when the input voltage exceeds the specified voltage, the power saving tap is selected, the output voltage is reduced by the transformer, and the power saving operation is performed. After the above, the standby time is set before the tap is switched, and the time limit is defined by the timer circuit 18. The time length of the timer circuit is set at the time of product shipment or adjusted and fixed according to the site when the power saving device is installed.

[0004]

In the case of the above-mentioned prior art, when the count time of the timer circuit, which is the tap switching time, is short, the responsiveness to the voltage change is good, but the voltage change is concentrated around the switching voltage. As a result, voltage fluctuations are amplified, and there are problems such as flickering of lighting, increase in the number of times of switching, wear of switch contacts for switching progressing quickly, and increase in failures.
Further, when the waiting time is long, the direct sending time tends to be long, and there is a problem that the power saving effect cannot be obtained much.

In view of the above problems, the present invention provides a tap-switching power-saving device that performs an effective power-saving operation without setting a standby time and that does not cause frequent switching of taps or flickering of lighting. The task is to provide

[0006]

In order to solve the above-mentioned problems, the invention of claim 1 is to switch between a direct transmission state without a transformer by switching a tap and a power saving state in which an input voltage is stepped down and output by the transformer. A tap switching type power saving device that outputs, a tap switching circuit that switches the tap, an input voltage detection circuit, and a standby time for counting a standby time from when an input voltage becomes equal to or higher than a specified voltage to when the device switches to the power saving state. Counting means, an elapsed time counting means for counting an elapsed time since switching to the power saving state, and a control means for controlling a tap switching circuit, wherein the control means includes an input voltage detection circuit and the two counting means. And a tap switching circuit for controlling the tap switching circuit and controlling the time period of both counting means.

According to a second aspect of the present invention, in the first aspect, the standby time counting means and the elapsed time counting means include a plurality of timer circuits each having a different time limit, and a timer selection circuit for selecting a timer circuit. The control means controls the timer selection circuit to control the time limit.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the control means shortens the time limit when the change interval of the input voltage is short, and shortens the time limit when the change interval is long. Thus, the control operation of the standby time counting means and the elapsed time counting means is performed.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit block diagram of a tap switching type power saving device according to the present invention, wherein 1 is a transformer tap switching section, 2 is a tap switching circuit, 3 is a voltage detection circuit, 4 is a central control circuit, 5 is a timer selection circuit. Reference numeral 6 (6a, 6b, 6c) denotes a standby time counting timer (hereinafter, referred to as a standby time timer) for counting a standby time from when the input voltage becomes equal to or higher than the specified voltage to when the tap is switched to the power saving state. 7 (7a, 7b, 7
c) is an elapsed time counting timer (hereinafter referred to as an elapsed time timer) for counting the elapsed time after returning to the power saving state, and three sets of timers a, b, and c are provided. The timer operation period is set longer in the order of c, for example, a is 15 minutes and c is 1 hour.

The operation will be described below with reference to FIG. 2 showing the correspondence between the input voltage and the on / off operation of the tap. First, the voltage detection circuit 3
When the voltage detected in step (1) is equal to or lower than the specified voltage Vt, the central control circuit 4 receives the information, operates the tap switching circuit 2, switches the tap 1 of the transformer, and performs a direct transmission operation without the transformer (point H). ). Thereafter, the voltage detection circuit 3 continues to monitor the input voltage, and when the input voltage exceeds the specified voltage Vt, transmits the information to the central control circuit 4.

The central control circuit 4 receives the information from the voltage detection circuit 3 and selects, for example, 6a from the standby time timer 6 selected by the timer selection circuit 5, and counts down the standby time. When the countdown is completed, the information is transmitted to the central control circuit 4 to perform a switching operation and enter a power saving state (point I), and at the same time, the timer selection circuit 5 switches the long-time timer 6b of the standby time timer 6. select.

Next, after returning to the power saving state, the countdown is performed by the elapsed time timer 7b paired with the selected timer 6b, and if the state below the specified voltage Vt does not occur again until the counting is completed, Timer selection circuit 5
The standby time timer 6b selected by the
Then, the time period of the standby time is shortened. But,
If the voltage becomes equal to or lower than the specified voltage Vt before the countdown of the elapsed period timer 7b is completed, the standby time after voltage recovery is longer than the initial state without changing the selected standby time timer 6b.

When the standby time timer 6b counts down and returns to the power saving state, the standby time timer 6b
6c is selected, and the standby time is set longer. Thereafter, if the voltage does not fall below the specified voltage Vt by the time the countdown of the elapsed time timer 7c ends, the standby time timer 6 is reselected from 6c to 6b, the standby time becomes shorter, and the countdown ends. When the voltage falls below the specified voltage, the standby time timer 6 proceeds to the next control while 6c is selected, and thereafter performs the same control.

As described above, in this circuit, every time an undervoltage condition occurs in which the input voltage becomes equal to or less than the specified voltage, the switching standby time for starting the power saving operation after the voltage is restored is increased. Even if a state below the specified voltage frequently occurs at short intervals, the tap switching operation is not performed each time, so that a sudden voltage fluctuation due to the tap switching is suppressed, and flickering of lighting or the like is prevented. On the other hand, when the state of the undervoltage does not occur for a long time, the standby time is shortened, and when the voltage becomes equal to or higher than the specified voltage, the operation is quickly returned to the power saving operation, thereby preventing a reduction in the power saving effect. . In FIG. 2, P indicates an operation area of the standby time timer 6, and Q indicates an operation area of the elapsed time timer 7.

FIG. 3 is a circuit block diagram showing a second embodiment, and FIG. 4 shows an operation flowchart thereof. In this case, unlike the above-described embodiment, the timer unit is composed of a set of a programmable standby time timer 9 and a programmable elapsed time timer 10, incorporated in the microcomputer 11, and directly sets the timer time limit by the central control circuit 8. It is configured to control.

The circuit operation will be described. In step S1 (step 1), the voltage detection circuit 3 determines whether the input voltage is equal to or higher than a specified voltage. If so, the central control circuit 8 receives the signal and the standby time timer 9 A countdown is started (S2). Then, it is determined whether or not the countdown is completed in S3. When the countdown is completed, the process proceeds to S4, and the tap switching circuit 2 is operated to switch the tap 1 of the transformer to power saving. If the standby time is not completed, the process returns to S2 to continue the countdown.

After switching the tap to the power saving operation, the process proceeds to S5, where the central control circuit 8 adds, that is, lengthens the count time of the standby time timer 9 and the elapsed time timer 10, and proceeds to S6.
Proceed to. In S6, the elapsed time timer 10 starts counting down, counts the elapsed time after switching, and if the undervoltage is not reached until the countdown ends, the result is transmitted to the central control circuit 8, and the standby time timer 9 and the elapsed time The count time of the timer 10 is subtracted, that is, shortened, and the process proceeds to S6.

However, if an undervoltage condition occurs during the countdown in S6, the processing flow shifts to undervoltage processing in S7 and is switched to direct delivery, and the count time of the standby time timer 9 and the elapsed time timer 10 is It remains added. That is, if the state returns to the specified voltage Vt or less again before the fixed time (time set by the elapsed time timer) has elapsed after the power saving recovery, the waiting time for the recovery becomes longer. Conversely, after returning to the power-saving operation, if the power-saving state continues for a certain period of time in S8, the process proceeds to S9, in which the count time for both the standby time and the elapsed time is gradually shortened. To return to the power saving state.

As described above, if a software programmable timer is used, the standby time and the elapsed time can be freely expanded and contracted by using two timers, and the tap switching process can be efficiently performed in accordance with the interval of the voltage fluctuation. Becomes

[0020]

As described in detail above, according to the first and second aspects of the present invention, the tap switching standby time from when the input voltage becomes equal to or higher than the prescribed voltage to when the tap is switched to the power saving state can be selected. Is adjusted by the control means in accordance with the voltage fluctuation state, it can be automatically adjusted, and there is no need to measure the interval of voltage fluctuation at the installation location, and the installation work can be simplified.

According to the third aspect of the present invention, in addition to the effects of the first and second aspects, even if a state below a specified voltage occurs in a short interval, a tap switching operation does not occur every time. As a result, it is possible to suppress rapid voltage fluctuation due to tap switching and prevent flickering of lighting or the like.
If the voltage drops below the specified voltage only at long intervals, the power saving operation can be started in a short standby time, and the power saving effect can be prevented from lowering.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a tap-switching power saving device showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an input voltage and a tap on / off time of the circuit of FIG. 1;

FIG. 3 is a circuit block diagram showing a second embodiment of the present invention.

FIG. 4 is a flowchart showing a flow of the operation of FIG. 3;

FIG. 5 is a circuit block diagram of a conventional tap switching type power saving device.

FIG. 6 is a diagram illustrating a relationship between an input voltage and a tap on / off time of the circuit of FIG. 5;

FIG. 7 is another diagram showing a relationship between an input voltage and a tap on / off time of the circuit of FIG. 5;

[Explanation of symbols]

1. Transformer tap, 2. Tap switching circuit, 3. Voltage detection circuit, 4. Central control circuit, 5. Timer selection circuit, 6. Standby time timer, 7. Elapsed time timer, 8 ..Central control circuit, 9.Standby timer, 1
0: Elapsed time timer, 11: microcomputer, Vt:
Specified voltage.

Claims (3)

[Claims] 1. A tap-switching power-saving device for switching between taps to switch between a direct-transmission state without a transformer and a power-saving state in which an input voltage is stepped down and output by a transformer, wherein the tap switching circuit switches the taps. An input voltage detection circuit, standby time counting means for counting a standby time from when the input voltage becomes equal to or higher than a specified voltage to switching to the power saving state, and an elapsed time for counting an elapsed time since switching to the power saving state Counting means, and control means for controlling the tap switching circuit, the control means receives signals from the input voltage detection circuit and the two counting means, controls the tap switching circuit, and sets the time limit of both counting means. A tap switching type power saving device to be controlled. 2. The apparatus according to claim 1, wherein the waiting time counting means and the elapsed time counting means include a plurality of timer circuits each having a different time limit, and a timer selecting circuit for selecting the timer circuit. The control means controls the timer selecting circuit. The tap-switching power-saving device according to claim 1, wherein the time period is controlled by controlling the time period. 3. The control operation of the standby time counting means and the elapsed time counting means such that the time period is lengthened when the change interval of the input voltage is short, and conversely, the time period is shortened when the change interval is long. The tap switching type power saving device according to claim 1 or 2, wherein