JP2000261981A - Protecting apparatus for uninterruptive power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress red heat and smoke generation of a varistor inserted into the input side of an unintierruptive power supply unit, by providing connectively a voltage-sensing circuit between its neutral and grounding terminals, and by breaking via a solid-state relay its input-side current, when sensing the generation of a voltage not smaller than a fixed value. SOLUTION: Between a grounding terminal G and a neutral terminal N of the input side of an uninterruptive power supply unit 1, a voltage-measuring circuit (sensor) 2 is provided connected to measure always its input voltage. A control circuit 4 always compares a measured voltage V with a preset voltage (reference voltage) VO. When the voltage V exceeds the voltage VO, the control circuit 4 sends a signal to a solid-state relay(SSR) 3 to break a hog-side circuit connected to the uninterruptive power supply unit 1. At the same time, the control circuit 4 sends a signal to an alarm unit 5 to issue to workers an alarm by a sound/light. As a result, the uninterruptive power supply unit 1 itself can be prevented from being destroyed by an abnormality voltage, and the connecting of a varistor, etc., with it can be dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for an uninterruptible power supply for protecting a load when an abnormal voltage is generated between a power supply ground and a hot ground and / or between a ground and a neutral. It is about. Generally, power transmitted from a power company is supplied to each device from an outlet via a high-voltage power receiving unit, a substation, and a low-voltage power distribution unit in a building. In a three-wire single-phase system often used in Japan, as shown in FIG.
Two windings of 0 volt are prepared, both are connected in series, and the midpoint is grounded near the transformer to form a neutral line. In this system, the two power circuits share a neutral line,
If two load L ₁ and L ₂ are the same mutually cancel each other out the reverse current, the neutral line as a result has a configuration as current does not flow.

However, when an imbalance occurs in the power supply load, the current I (ampere) is applied to the neutral line.
Flows. From the neutral wire transformer to the load, there is a combined electrical resistance R (ohm) such as the electrical resistance of the electric wire itself and the terminal partial contact resistance. As a result, between the transformer side terminal (B) and the load side terminal (E) of the neutral line,
A voltage of VE = I * R volts will result. That is, when are seen in the load L ₁ terminal, neutral (E)
And a ground (G). On the other hand, the voltage between hot (D) and neutral (E) is
100 volts are supplied from the secondary winding of the transformer. Therefore, the voltage between the hot terminal (D) and the ground (G) is 100 + VE volts. Usually VE
Is within several volts. However, if an abnormality occurs at the terminal of the neutral wire due to factors such as improper tightening, V
E can exceed tens of volts.

[0003]

2. Description of the Related Art On the other hand, recent equipment such as a computer uses a power supply with a ground terminal for the purpose of security of the equipment. In this case, the ground line is wired to the outlet independently of the neutral line. In a computer and an uninterruptible power supply used in the same, as shown in FIG. 2, between a hot (D) and a neutral (E), a hot (D) and a ground (G) for the purpose of protecting against an abnormal voltage of a power supply. Between and neutral (E) and ground (G)
Varistors are often inserted between them. If an abnormal voltage is generated in the power supply, the energy caused by the abnormal voltage is released to the ground side by the varistor. In addition, when the energy of the abnormal voltage is large, the varistor itself is damaged to protect the load equipment from damage. In general, the duration of such a voltage abnormality often has a short time of about several milliseconds, and the time during which a current caused by the abnormal voltage flows through the varistor is extremely short. The varistor may be explosively damaged by such an abnormal current having a short duration, but there is no danger that the varistor will glow red and ignite surrounding parts.

In the prior art, as shown in FIG. 2, when an abnormal voltage is generated between ground (G) and hot (H) and / or neutral (N), varistors 10, 12,
13, the electric energy is transferred to the ground (G).
Side so that abnormal voltage is not applied to the uninterruptible power supply main body. The operation start voltage of this varistor is often set to about 150 volts as an average value (Root mean square).

[0005]

When a varistor selected in accordance with such a standard is used, an accident occurs in which the varistor emits smoke or emits a fire and damages surrounding electric parts in actual use. I have. In order to prevent such accidents, the following measures (1) to (3) have been taken, but each has a drawback. (1) The operation start voltage of the varistor is set high. For example, the operation start voltage of the varistor is 300 to 400 in average.
Bolts. In such a setting, smoking / flaming accidents hardly occur. However, this measure results in a large abnormal voltage being applied directly to the uninterruptible power supply. This voltage is a voltage between the ground and the terminal, which rarely damages the device immediately, but has a bad influence such as shortening of the life of the device in a long term. (2) Do not insert a varistor. Ground and hot and / or
Or, if the varistor is not inserted between the neutrals, the varistor does not emit smoke / flame. However, in this case, a problem such as shortening of the life of the device occurs for the same reason as described above. (3) Use a special varistor. If a special varistor that does not emit or emit smoke is used, the smoke can suppress the generation of flame. However, even in this case, it is inevitable that the varistor itself will be heated until it glows red. Therefore, there is a possibility that peripheral electric components and the like may be damaged by the heat radiation.

However, in the case of a power supply abnormality as described above, which occurs due to a combination of load imbalance and poor connection, the power supply may continue for a relatively long time, for example, more than several seconds. If such an abnormal current continues for a long time, there is a risk that the varistor may emit red heat or flame and ignite surrounding parts.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and has an uninterruptible power supply having a ground terminal, a neutral terminal, and a hot terminal used for single-phase alternating current, and A single-phase AC power supply connected to the hot terminal and the neutral terminal, a solid-state relay (hereinafter referred to as SSR) connected between the single-phase AC power supply and the hot terminal, and a neutral of the connected uninterruptible power supply device The voltage measurement circuit connected between the terminal and the ground terminal is constantly compared with a preset voltage (reference voltage) based on the output signal of the voltage measurement circuit. If the measured voltage is higher than the reference voltage, a signal is sent to the SSR. Control circuit to send a signal to the hot side circuit to the uninterruptible power supply and cut off the current to the uninterruptible power supply. Ri to achieve this purpose.

According to a second aspect of the present invention, the voltage measuring circuit is connected between the hot terminal and the ground terminal.
According to the invention, the voltage measuring circuit is connected between the neutral terminal and the ground terminal and between the hot terminal and the ground terminal of the uninterruptible power supply. According to a fourth aspect of the present invention, the interruption of the current to the uninterruptible power supply is continued until the control circuit transmits a reset signal.
According to the invention, the reset signal is generated only when the voltage is equal to or lower than the reference voltage for a predetermined time.

[0009]

When the detection circuit detects that a certain voltage or more is generated between the neutral and the ground, the SSR is output.
By cutting off the current on the input side through the, the varistor inserted into the uninterruptible power supply is suppressed from red heat and flaming.
Since this device is grounded to the input side of the uninterruptible power supply, even if the input side current of the uninterruptible power supply is interrupted by the operation of this device, power is supplied from the storage battery of the device to the load side device for a certain period of time. Since the power is supplied, no problem occurs in the operation of the load device. Also, with the interruption of the power supply current,
The occurrence of a power failure is notified to an administrator or the like by an alarm sound or light.

As measures to be taken after the current is interrupted due to a voltage abnormality between ground and hot and / or neutral, the present invention supports a plurality of methods described below. (1) Keep the current off until the power supply is repaired. In this case, when viewed from the uninterruptible power supply, this is equivalent to the occurrence of a power outage, and the load device must be safely stopped within the power supply continuation time determined by the capacity of the battery according to the signal of the power outage occurrence from the uninterruptible power supply. . (2) The control circuit confirms that no abnormal voltage is generated again for a certain period of time (for example, several seconds) after the voltage abnormality between the ground and the hot and / or neutral is restored to the normal state. To resume power supply. In this case, as long as the duration of the abnormal voltage does not exceed the duration of energization determined by the battery capacity of the uninterruptible power supply, the load-side device can maintain the operating state. The uninterruptible power supply outputs a signal indicating occurrence of a power failure to the computer via a communication line. Therefore, if a computer is connected to the uninterruptible power supply, the occurrence of a power failure can be recorded by the power failure management software. The presence / absence of abnormality and the time can be confirmed. In order to avoid such a fire accident, conventionally, no varistor is inserted between hot / ground and / or neutral / ground, or the operating voltage of the varistor to be inserted is set high. However, such measures mean that the equipment is not protected against voltage abnormalities between ground and neutral or hot, and in the long term, the damage to the equipment will be accelerated and, in some cases, operation It causes defects and the like.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in FIGS. FIG. 3 shows a circuit configuration of an embodiment of the present invention. A known uninterruptible power supply 1 having a hot terminal (H), a neutral terminal (N), and a ground terminal (G), and an input of the power supply 1 Ground terminal (G) and neutral terminal (N)
A voltage measuring circuit 2 is connected between the
Input voltage V is constantly measured. 4 is a control circuit connected to the output terminal of the measuring circuit 2, the circuit 4 compares constantly the voltage (reference voltage) V0 that is set in advance and the measured voltage, the reference measured voltage V is a voltage V ₀ Is exceeded, a signal is sent to the solid state relay 3 (SSR) to shut off the hot side circuit to the UPS. At the same time, it is configured to send a signal to the alarm 5 to issue an alarm to the worker by sound and / or light. The voltage V between the ground (G) and the neutral (N) is the reference value V
_{When the} voltage returns to ₀ or less, if the voltage V does not exceed the reference value V ₀ during the fixed time Δt, the control signal to the SSR 3 is turned off from on to return the input side current to the uninterruptible power supply 1. . On the other hand, the control signal to the alarm device 5 is configured to continue to issue an alarm until a manual alarm cancellation command is issued.

FIG. 4 is a timing chart showing the relationship between the power supply of the apparatus according to the embodiment and the operation of the apparatus. The operation of the apparatus according to the embodiment will be described with reference to this chart. Ground (G) · Neutral (N) _{t 0} measured voltage V is less than the reference voltage _{V 0} which between
In the state of ~t _1, since the current cut-off command to the control circuit 4 SSR3 is not issued, the load such as a computer from the uninterruptible power supply 1 with an input current to the uninterruptible power supply unit 1 flows device 6 , A current is output. At this time, no current is supplied from the storage battery in the uninterruptible power supply 1 to the load device, but the battery is in a charged state.

Next, during the period from t _{1 to} t ₂ , the measured voltage V
There has been a state higher than the reference voltage V _0. Therefore, the control circuit 4 that has obtained the measurement result from the voltage measurement circuit 2
Performs a comparison with the reference voltage, and instructs the SSR 3 to cut off the current supply at the hot terminal in order to determine a voltage abnormality. As a result, the uninterruptible power supply 1 is in a power outage state, and the power supply to the load device 6 is switched to that from the storage battery. Further, the power failure state due to the abnormal signal and the start time of the power failure state are transmitted from the uninterruptible power supply 1 to the load device 6 such as a computer via a communication circuit, and the information is stored in the memory of the computer. Is stored.

In the state of t _{2 to} t ₃ in the timing chart, first, at time t ₂ , the measured voltage V becomes lower than the reference voltage. The low state continues for at least Δt seconds. Then, the control circuit determines that the abnormal state has been resolved after elapse of Δt seconds, issues a current cutoff release command to the SSR 3, starts supplying current to the uninterruptible power supply 1, and simultaneously loads the load device 6 from the storage battery. The supply of current to is stopped. Then, the storage battery shifts to a charged state. In addition, in this switched state, the fact that the uninterruptible power supply has ended and the time are transmitted from the uninterruptible power supply 1 to the computer, and the computer additionally writes such information to the memory.

The state between t _{3 and} t ₄ indicates a state where the measured voltage suddenly fluctuates abnormally with the reference voltage. The control circuit 4 detects this state and immediately issues a current supply cutoff command to the SSR 3. The current supply to the uninterruptible power supply 1 is stopped, and the power supply is switched to the power supply from the storage battery of the uninterruptible power supply 1. Then, the uninterruptible power supply 1 transmits the power failure state and the time to the computer. However t
_{After 4} seconds, since the measured voltage V has dropped below the reference voltage V ₀ , the control circuit 4 detects that the abnormal state has ended after Δt seconds, issues a shutdown release command to the SSR 3, and issues an uninterruptible power supply. 1 and the storage battery shifts from the power supply state to the power storage state.

In this embodiment, the voltage measurement is connected between the hot terminal and the neutral. However, the present invention is not limited to this. The voltage measurement may be connected between the ground and the hot terminal and between the neutral and the ground. good.
Further, the configuration is such that the abnormal state and the return state are transmitted from the uninterruptible power supply 1 to the computer. However, the present invention is not limited to this.
The transmission may be performed in the OFF state, and it goes without saying that the temporal timing may be configured to be stored in the memory based on the clock in the computer.

[0017]

As described above, the protection device for an uninterruptible power supply according to the present invention can prevent the uninterruptible power supply itself from being destroyed by an abnormal voltage, as compared with the conventional device. It is not necessary to connect a varistor or the like in the uninterruptible power supply.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram of a conventional three-wire single-phase AC power supply.

FIG. 2 is a block diagram schematically showing a conventional protection device for an uninterruptible power supply.

FIG. 3 is a block diagram of a protection device showing an embodiment according to the present invention.

FIG. 4 is a timing chart showing a control state by the protection device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Uninterruptible power supply 2 Voltage measurement circuit 3 SSR 4 Control circuit 5 Alarm 6 Load device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G004 AA01 AB02 BA07 CA02 CA03 DC04 DC09 EA01 FA01 GA01 5G015 FA02 GA01 GB01 JA32 JA34 JA42 JA43 JA44 JA45 JA52 KA03

Claims (6)

[Claims] 1. An uninterruptible power supply having a ground terminal, a neutral terminal, and a hot terminal used for single-phase alternating current,
A single-phase AC power supply connected to a hot terminal and a neutral terminal of the device, a solid-state relay (hereinafter referred to as SSR) connected between the single-phase AC power supply and the hot terminal, and the connected uninterruptible power supply A voltage measuring circuit connected between the neutral terminal and the earth terminal of the device;
A preset voltage (reference voltage) is constantly compared based on the output signal of the voltage measurement circuit, and if the measured voltage is equal to or higher than the reference voltage, a signal is sent to the SSR so that a hot side circuit to the uninterruptible power supply is provided. A protection device for an uninterruptible power supply, comprising a control circuit for sending a signal and interrupting a current to the uninterruptible power supply. 2. An uninterruptible power supply having a ground terminal, a neutral terminal, and a hot terminal used for single-phase alternating current;
A single-phase AC power supply connected to a hot terminal and a neutral terminal of the device, a solid-state relay (hereinafter referred to as SSR) connected between the single-phase AC power supply and the hot terminal, and the connected uninterruptible power supply A voltage measuring circuit connected between the hot terminal and the ground terminal of the device is constantly compared with a voltage (reference voltage) set in advance based on an output signal of the voltage measuring circuit. If the measured voltage is higher than the reference voltage,
A control circuit that sends a signal to the SSR to send a signal to the hot side circuit to the uninterruptible power supply and cuts off current to the uninterruptible power supply. 3. An uninterruptible power supply having a ground terminal, a neutral terminal, and a hot terminal used for single-phase alternating current;
A single-phase AC power supply connected to a hot terminal and a neutral terminal of the device, a solid-state relay (hereinafter referred to as SSR) connected between the single-phase AC power supply and the hot terminal, and the connected uninterruptible power supply The voltage measurement circuit connected between the neutral terminal and the ground terminal and between the neutral terminal and the ground terminal of the device is constantly compared with a preset voltage (reference voltage) based on the output signal of the voltage measurement circuit. If the voltage is higher than
A control circuit for sending a signal to the R to send a signal to the hot side circuit to the uninterruptible power supply and interrupting the current to the uninterruptible power supply. 4. The apparatus according to claim 1, wherein interruption of current to the uninterruptible power supply is continued until a control circuit issues a reset signal.
4. The protection device for an uninterruptible power supply according to claim 3. 5. The control circuit according to claim 1, wherein a reset signal of the control circuit is automatically transmitted from the control circuit when a predetermined time has elapsed after the abnormal interruption has returned to normal after the current interruption. The protection device for an uninterruptible power supply according to claim 4, characterized in that: 6. The protection device for an uninterruptible power supply according to claim 1, wherein an alarm is issued by a light, a sound or the like at the same time as said current interruption through an alarm device.