JPH054695Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a terminal block that can protect equipment from surge voltages caused by lightning or the like that invade power lines and signal lines.

(Background technology) Figure 10 shows a fluorescent lamp using semiconductor switch _Q1 .
A circuit for controlling FL lighting is shown. Fluorescent light FL
At one end of each filament, there is a semiconductor switch Q ₁ such as a thyristor and a ballast L ₁ which acts as a current limiting element.
An alternating current power source V is connected via the . fluorescent light
At each other end of the FL filament, there is a glow lamp G for starting the fluorescent lamp and a capacitor for noise prevention.
C ₀ is connected in parallel. Such a lighting fixture includes, in addition to the circuit elements shown in FIG.
It has parts (for example, lamp sockets, glow sockets, etc.) for attaching these circuit elements. In addition, the chassis (equipment body) for attaching these parts is usually made of metal and may be grounded (if the input voltage or secondary voltage of the stabilizer exceeds 150V,
Grounding is required by laws such as the Electrical Appliance and Material Control Law. ).

In such a circuit, a surge voltage of several kilovolts may be applied to the power supply line due to induced lightning, etc. In this case, two types of modes can be considered. One is a normal mode, that is, a case where a surge voltage is applied between power supply lines. In this case, it is possible to protect it by connecting a voltage protection element such as a zinc oxide varistor in parallel with the power supply V or in parallel with a part vulnerable to high voltage such as the semiconductor switch _Q1 . The other case is common mode, that is, when a surge voltage is applied between the line and ground. In particular, this common mode occurs when the line is in a floating state. Such a floating state of a line is relatively easy to occur because recently, there has been an increase in the number of devices, including telephone lines, that are controlled using signal lines. Furthermore, even if one end of the line is grounded, a common mode surge voltage may be applied depending on the line impedance of the ground. Now, in the circuit shown in Figure 10, if a common mode surge voltage is applied between the a-phase of the power supply line and the ground, and the chassis (equipment main body) is grounded, for example, the surge voltage When the dielectric strength between the lamp socket and the chassis is exceeded, a discharge loop is formed between the lamp socket and the chassis at point P in the circuit diagram. The surge current at this time is
Since there is no large current-limiting impedance element on the circuit, the current becomes extremely large, exceeding the current withstand capacity of the semiconductor switch _Q1 , and causing damage to the semiconductor switch _Q1 . To prevent this, it is best to increase the dielectric strength of the lamp socket, ballast _L1 , etc.
Increasing the dielectric strength will make the parts larger, and
Since countermeasures must be taken individually for each of the various parts used in the equipment, there is a problem in that costs increase.

Another measure against common mode surge voltage is to install voltage protection elements AV 1 , AV ₁ ,
Another option is to connect AV ₂ . However, the failure modes of these devices are:
There is also a failure mode where a short circuit occurs, and in this case, current from the power line flows through the chassis, so
There is a risk of electric shock. Furthermore, due to the capacitance of the element, leakage current to the ground increases when a large number of devices are connected in parallel, which may cause malfunction of the earth leakage breaker.

(Purpose of the invention) The present invention was made in view of the above points, and its purpose is to prevent electric shock without increasing the dielectric strength of individual parts used in equipment. The object of the present invention is to provide a terminal block with a simple configuration that can protect equipment from surges by implementing surge countermeasures against common mode using a method that does not pose such dangers.

(Disclosure of the invention) The terminal block according to the invention has input lines a and b connected to it, and electrically connects the input lines a and b to a device, as shown in FIGS. 1 to 3, for example. In the terminal block T for connecting the input lines a and b, cut and raise a part of the chassis 2
By bringing the electrically conductive plates 1a, 1b close to the electrically conductive plates 1a, 1b to be connected, a surge voltage is discharged between the cutouts 2a, 2b of the chassis 2 and the electrically conductive plates 1a, 1b at a voltage lower than the dielectric strength of the equipment. A discharge gap 3 is formed that can be used.

Since the present invention is configured in this way, even if a common mode surge voltage is applied to the input lines a and b, the surge voltage is prevented from discharging between the conductive plates 1a and 1b and the cut-out portion of the chassis 2. If the dielectric strength voltage at gap 3 is exceeded, the surge voltage will be discharged at this discharge gap 3, so the surge voltage will not enter the inside of the device, and the device can be reliably protected from surge voltage. Moreover, when there is no surge voltage, no current leaks from the input lines a and b to the chassis 2 via the discharge gap 3.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram of a non-contact switching emergency light using a terminal block according to an embodiment of the present invention. The AC power supply voltage supplied from the terminal block T to the device side is applied to the primary side of the charging transformer Tf. A capacitor is installed on the primary side of the charging transformer Tf.
A series circuit of _C1 and fuse F is connected in parallel. A voltage protection element AV ₁ is connected in parallel to both ends of the capacitor C ₁ . A charging circuit X including a rectifier circuit and a current limiting element is connected to the secondary side of the charging transformer Tf. Storage battery B is being charged by the output of charging circuit X. Storage battery B
The output of is supplied to the inverter INV. On the other hand, the AC power supply voltage supplied from the terminal block T to the equipment side is connected to a semiconductor switch _Q1 such as a triac.
and current-limiting element ballast L ₁ through fluorescent lamp FL
is connected to one end of each filament. A voltage protection element AV ₂ is connected in parallel to both ends of the semiconductor switch Q ₁ . A trigger circuit consisting of a series circuit of a trigger element Q ₂ and a resistor R ₁ is connected to the gate of the semiconductor switch Q ₁ , and this trigger circuit receives a trigger voltage from the middle of the primary winding of the charging transformer Tf. is supplied. inverter
The output voltage of INV is applied to each other end of the filament of the fluorescent lamp FL. A series circuit of a starting glow lamp G and a current limiting element _L2 is connected to each other end of the filament of the fluorescent lamp FL. When the AC power supply V is not interrupted, the thyristor
_Q1 is triggered by the trigger circuit, and the limited current is supplied to the fluorescent lamp FL via the ballast _L1 , and the fluorescent lamp FL is turned on. When AC power supply V has a power outage, the voltage from storage battery B is transferred to inverter INV.
This high frequency AC voltage is used to light the fluorescent lamp FL.

In this embodiment, in addition to the discharge gap 3 provided on the terminal block T, protection against surge voltage in the normal mode is provided by voltage protection elements AV ₁ and AV ₂ . In addition, the discharge gap 3 provided on the terminal block T protects against common mode surge voltages, so that surge voltages inside the equipment can be prevented from reaching lamp sockets and ballasts.
It does not exceed the dielectric strength of _L1, etc., and can prevent overcurrent breakdown of semiconductor switch _Q1 , etc. Although FIG. 1 shows an example of a non-contact switching type emergency light, any device may be used as long as it is a device to which a surge voltage may be applied.

Next, a specific structure of the terminal block will be explained. FIG. 2 is an exploded perspective view of the tightening type power terminal block used in the circuit of FIG. 1, and FIG. 3 is a longitudinal sectional view of this terminal block. The power wire is inserted between the terminals 7a, 7b and the conductive plates 1a, 1b, and the terminal screw 6
It is connected by tightening a and 6b.
The conductive plates 1a and 1b are attached to a body 4 made of an insulator using studs 8. In order to protect the live parts, a cover 5 made of an insulating material is attached to the upper surface of the body 4. In order to attach the terminal block to the chassis 2, a slit 4d provided on the back side of the body 4 of the terminal block has a
The cut-out portions 2a and 2b are inserted and positioned, and the body 4 is further fixed to the chassis 2 through the round hole 2c of the chassis 2 with a terminal block mounting screw 9. Cut-outs 2a, 2 from chassis 2
b serves as positioning during installation, and at the same time as the third
As shown in the figure, a discharge gap 3 is formed between the conductive plates 1a and 1b.

A pair of round holes 5a, 5b for tightening the terminal screws 6a, 6b are formed in portions of the cover 5 corresponding to the terminal screws 6a, 6b. Further, on the lower surface side of the cover 5, an engaging claw 5c used for coupling with the body 4 is provided to protrude downward.
One end of the conductive plates 1a, 1b is bent approximately vertically to form a discharge gap 3. This vertical bent portion 11 is bent toward the inside of the body 4. A substantially U-shaped notch 12 is provided on the other end side of the conductive plates 1a and 1b, and this notch 12 has the following shapes:
Terminal screws 6a, 6b screwed onto terminals 7a, 7b
is now being installed. terminal screw 6a,
6b is arranged on the power supply side of the terminal block, and is connected to the conductive plate 1a,
The vertical bent portion 11 of 1b is arranged on the load side. The conductive plates 1a, 1b are provided with round holes 13 through which the driving studs 8 are inserted. Terminal screws (not shown) or the like for connection to the inside of the device are appropriately mounted in round holes 14 near the load side in the conductive plates 1a and 1b.

The chassis 2 has a round hole 2c through which a screw 9 for fixing the body 4 is inserted, and near the round hole 2c there is a vertical fold of the conductive plates 1a, 1b. A pair of cut and raised portions 2a and 2b are provided so as to correspond to the curved portion 11. As you can see from the longitudinal cross-sectional view in Figure 3, the body 4
A slit 4d is provided at the bottom near the load side of the chassis 2, through which the cutouts 2a and 2b from the chassis 2 are inserted. The chassis notches 2a, 2b inserted through the insertion holes 4d are inserted into the body 4 to drive studs 8.
Vertical bent portion 1 of conductive plates 1a and 1b fixed at
The discharge gap 3 is arranged to face the discharge gap 3.
is formed. The discharge gap 3 is set to discharge at a voltage lower than the voltage that would cause dielectric breakdown of the equipment on the load side. The distance of the discharge gap 3 varies depending on the shape, temperature, humidity, atmospheric pressure, application time, etc., but according to "Electrical Insulation" [translated by Yasuhiro Matsumoto, published by Kindai Kagakusha (S35.12.1)], page 19. , is determined according to a characteristic diagram as shown in FIG.

A pair of conductive plates 1a, 1 are provided in the center of the body 4.
A partition wall 40 is provided to separate the cover 5, and a pair of rectangular engagement holes 4c for engaging the engagement claws 5c of the cover 5 are provided in the partition wall 40.
Furthermore, a mounting hole 43 is provided in the center thereof, into which a mounting screw 9 between the body 4 and the chassis 2 is inserted. A pair of conductive plates 1 are provided on both sides of the partition wall 40.
Recesses 4a and 4b are provided for accommodating elements a and 1b, respectively. A protruding part 41 for supporting the conductive plates 1a and 1b is provided at approximately the center in the longitudinal direction of the recesses 4a and 4b, respectively. fixing holes 42 are provided respectively. A notch is formed in the upper edge of the power supply side and load side surfaces of the body 4, and a gap is formed between the body 4 and the cover 5 for drawing out the lead wires connected to the power supply side and the load side, respectively. Letting it be formed.

FIG. 4 is an exploded perspective view of another embodiment of the present invention, and FIG. 5 is a longitudinal sectional view thereof. The same parts as in the previous embodiment are given the same reference numerals and redundant explanations will be omitted. This embodiment is the same tightening type terminal block as the previous embodiment, but the mounting structure of the body 4 to the chassis 2 is different. In this embodiment, a pair of bosses 4e for positioning protrude from the bottom surface of the body 4. This positioning boss 4e is connected to a pair of positioning round holes 2e provided in the chassis 2.
are inserted into each. The chassis 2 and the body 4 are fixed by a hook-shaped cutout 2d. This cut-and-raised portion 2d has a groove in the center and can be expanded to both sides. After inserting the notched part 2d into the mounting hole 43 in the center of the body 4 of the terminal block, insert the notched part 2d from the top of the body 4.
The body 4 is attached to the chassis 2 by deforming the body 4 so as to spread out the body 4, as shown in FIG.

FIG. 6 is an exploded perspective view of still another embodiment of the present invention, and FIG. 8 is a longitudinal sectional view thereof. In this embodiment, a substantially M-shaped engagement hole 22 is provided in the cut-out portion 21 on the chassis 2 side. The body 4 is provided with a pair of recesses 45 on both sides thereof, into which the cut and raised portions 21 from the chassis 2 are fixed. After the cutout portion 21 of the chassis 2 sandwiches the body 4,
It is bent so as to press both sides of the body 4 (see Fig. 7). The body 4 is formed with an M-shaped protrusion 46 that is fitted into the M-shaped recess 22 described above. A tongue piece 23 is provided at each end of the cut-out portion 21 from the chassis 2. The body 4 is provided with notches 47 into which the tongue pieces 23 are inserted.
7 is a recess 4a, 4b for accommodating the conductive plates 1a, 1b.
It communicates with The other configurations are the same as those in the previous embodiment, so explanations will be omitted. 8th
As is clear from the diagram, discharge gap 3 is
It is formed between the tongue piece 23 provided at the tip of the cut-out portion 21 from the chassis 2 and the side edges of the conductive plates 1a and 1b.

Note that this invention is not limited to terminal blocks connected to a commercial power source, but can protect devices from surge voltages as long as they are used in devices where surge voltages may enter from the outside. It has the effect of

(Effect of the invention) As described above, in the present invention, by cutting up a part of the chassis to be grounded and bringing the input line closer to the conductive plate to be connected, the cut-out part of the chassis and the conductive plate Since a discharge gap is formed between the input line and the input line that can discharge the surge voltage at a voltage lower than the dielectric strength of the equipment, even if a common mode surge voltage is applied to the input line, the surge voltage will be When the withstand voltage in the discharge gap between the chassis and the Therefore, when used in fluorescent lamp equipment, for example, it is necessary to improve the dielectric strength of various parts such as the lamp socket on the load side, the ballast, and the glow socket. Moreover, when there is no surge voltage, no current will leak from the input line to the chassis via the discharge gap, so there is no risk of electric shock, and there is no risk of malfunctioning of the earth leakage breaker, etc. There is an advantage that there is no

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an emergency light lighting device using a terminal block according to an embodiment of the present invention, Fig. 2 is an exploded perspective view of the same terminal block, and Fig. 3 is a longitudinal sectional view of the same terminal block. , FIG. 4 is an exploded perspective view of a terminal block according to another embodiment of the present invention, and FIG. 5 is a vertical cross-sectional view of the same terminal block.
FIG. 6 is an exploded perspective view of a terminal block according to still another embodiment of the present invention, FIG. 7 is a perspective view of a cut-out portion of a chassis used in the same, and FIG. 8 is a longitudinal cross-sectional view of the same terminal block; FIG. 9 is a diagram showing the relationship between the discharge gap and the discharge voltage, FIG. 10 is a circuit diagram of a conventional example, and FIG. 11 is a circuit diagram of another conventional example. a, b are input lines, T is terminal block, 1a, 1b
2 is a conductive plate, 2 is a chassis, and 3 is a discharge gap.

Claims (1)

[Scope of utility model registration request] In a terminal block to which an input line is connected and for electrically connecting the input line to a device, a part of the chassis to be grounded is cut and raised to bring the input line closer to the conductive plate to which the input line is connected. A terminal block comprising a discharge gap capable of discharging a surge voltage at a voltage lower than the dielectric strength of the device, between the cut-out part of the terminal block and the conductive plate.