WO1992003867A1

WO1992003867A1 - Surge suppressor device

Info

Publication number: WO1992003867A1
Application number: PCT/AU1991/000361
Authority: WO
Inventors: Frank Arthur Rogers; Raymond Ernest Scott
Original assignee: Mining And Primary Development Pty. Ltd.
Priority date: 1990-08-17
Filing date: 1991-08-15
Publication date: 1992-03-05

Abstract

Surge suppressor device (10) for connection into a circuit, comprising a transient suppressor (14) and indicator means (16, 18). The transient suppressor (14) limits transient voltages in the circuit. The indicator (18) provides indication that a transient voltage condition above a selected voltage level has occurred in the circuit. A current controller (26), which may be a zener diode (Z1), prevents passage of current through the indicator (18) when circuit voltage conditions are below the selected voltage level. A reverse polarity response arrangement may be provided and may comprise a fuse (28) and a diode (D2). An extended transient indication means may also be provided to extend the 'ON' time of the indicator when a transient voltage condition above the selected voltage level occurs in the circuit. The surge suppressor device may be used in the electrical systems of motor vehicles, marine craft and the like.

Description

SURGE SUPPRESSOR DEVICE DESCRIPTION The present invention relates to a surge suppressor device. The surge suppressor dt. ice of the present invention may be used in the electrical systems of motor vehicles and marine craft, and the like, to suppress or limit transient voltages which cause voltage surges/spikes in the circuit of the electrical system of the vehicle or craft.

FIELD OF THE INVENTION Present day vehicles and craft generally employ sophisticated electronic components in their electrical systems, e.g. electronic microprocessors such as electronic ignitions, fuel injection systems, cruise control, on-board computers, etc. Wnen transient voltages occur in the electrical system of the vehicle or craft serious damage can be caused to such components by the voltage surges/spikes that occur. This problem did not occur in older vehicles and craft since they did not incorporate such sophisticated circuit components . their electrical systems. K_3t of the electro-mechanical components commonly found in the electrical systems of these older vehicles and craft generally exhibit a wear-out phenomenon as electrical stresses are increased. In such an environment there is no need to distinguish between transient voltages and the normal load conditions.- Any transient condition that did occur was accounted for by simply increasing contact ratings, etc. However, the introduction of sophisticated circuit _ _

components, which may employ semiconductor materials, presents a different environment because such components exhibit a different sensitivity to voltage transients. Semiconductor components tend to have a "black and white" failure characteristic when exposed to voltage transients in that no damage is caused below a certain level and total failure results above a certain level. Unfortunately, these two levels are different and the problem is further complicated by the fact that the voltage (energy) tolerance of semiconductor components is normally subject to a production distribution.

Transient voltages in the form of voltage surges/spikes may occur in the circuit of the electrical system of the vehicle or craft. Such transient voltages may result from different causes, eg. "jump starting" a vehicle with a flat battery where the difference in voltages between the slave battery and the depleted power battery may be high. It is desirable to suppress or limit such transient voltages to levels that will keep potential damage to such components to a minimum, by suppressing or limiting such voltage transients to levels that can be tolerated by the electronic components in the electrical system. Further, when such voltage transients do occur there is no warning or indication of this other than the damaged components.

With suppression or limiting of the voltage transients the electronic components are not damaged, but it is still desirable that an indication of the transient voltage condition be provided, at least in the case of high voltage transients. An indication is also desirable when an overvoltage condition occurs in the circuit. Such indication of the existence of a transient voltage or an overvoltage condition serves as a warning that a problem may exist with the electrical system. Remedial action may then be undertaken to correct the problem, if necessary.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention there is provided a surge suppressor device comprising transient suppressor means to suppress or limit transient voltages in a circuit to which said surge suppressor device is connectable and indicator means able to indicate when a transient voltage or an overvoltage condition above selected levels occurs in said circuit. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view showing the outer casing of an embodiment of the surge suppressor device in accordance with the present invention; Figure 2 is a schematic diagram of a circuit of a first embodiment of the surge suppressor device of the present invention;

Figure 3 is a plan view of the upper side of an embodiment of a printed circuit board (PCB) layout for the circuit shown in Figure 2; Figure 4 is a plan view of the underside of the PCB shown in Figure 3;

Figures 5(a) to 5(d) show an embodiment of the casing of the surge suppressor device formed in two parts, with Figure 5(a) being a plan view of the interior of a first part of the casing;

Figure 5(b) being a cross-sectional view through the line B-B shown in Figure 5(a),

Figure 5(c) being a plan view of the exterior of a second part of the casing, and

Figure 5(d) being a cross-sectional view through the line D-D shown in Figure 5(c);

Figure 6 is a schematic diagram of a circuit of a second embodiment of the surge suppressor device of the present invention.

Figure 7(a) and Figure 7(b) form a functional or operational block diagram of the circuit shown in Figure ^" 6. DESCRIPTION OF THE INVENTION

In Figure 1 there is shown a perspective view of a surge suppressor device 10, showing the outer casing 12 thereof. With reference to Figure 2, the surge suppressor device 10 comprises a transient suppressor 14, an indicator 16 and another indicator 18.

Preferably, the indicators 16 and 18 are distinguishable from one another at least when they are activated. This may, for example, be on the basis that each glows a different colour. Alternatively, or additionally, the casing 12 may carry markings thereon to distinguish the indicators 16 and 18, as exemplified in the drawings with the "ON" and "FAULT" markings. Other suitable ways of distinguishing the indicators 16 and 18 may also be used. The transient suppressor 14, indicator 16 and indicator 18 are connected between a pair of connector leads 20 and 22 in parallel. As shown in Figure 2, the connector lead 20 - - is a "positive" lead and the connector lead 22 is a

"negative" lead.

The surge suppressor device 10 may further comprise reverse polarity response means 24 which responds to a reverse polarity condition.

The indicator 18 is connected in series with a current controller 26.

As shown in the diagram of Figure 2, the transient suppressor 14 may comprise a high speed transient suppressor in the form of a diode Dl whilst the indicators

16 and 18, respectively, may comprise light emitting d.. des

(LEDs) (LED1 and LED2, respectively).

The reverse polarity response means 24 may comprise a fuse de-ice 28 and a diode D2. The LED1 is connected in St -ies with a resistor Rl. The LED2 is connected in series with a resistor R2. The fuse device 28 is shown schematically in Figure 2 in relation to its location and nature.

The precise location of the fuse device 28 in the circuit of the surge suppressor device 10 is not critical provided that it is positioned s that when the fuse device 28 fuses, LED1 is disconnected from the circuit. Accordingly, the fuse device 28 may be located in the circuit line that extends from the current controller 26 to th resistor Rl, LED1 and the negative terminal 30.

The diode D2 is connected in parallel with the resistor Rl and the LED1. The diode D2 has its cathode connected to the positive terminal 32. As also shown in Figure 2, the current controller 22 may comprise a Zener diode Zl. The Zener diode Zl has its cathode connected to the positive terminal 32. The Zener diode Zl is in series connection with the resistor R2. The high speed transient suppressor diode Dl has its cathode connected to the positive terminal 32.

The fuse device 28 may comprise a fusible link in the circuit of the surge suppressor device 10. An embodiment of this is shown in Figures 3 and 4. Figure 3 is a plan view of the upper side of an embodiment of the layout of a PCB 34 for the circuit of the surge suppressor device 10 shown in Figure 2.

Figure 3 shows the components of the circuit of the surge suppressor device 10 positioned on the upper side of the PCB 34 in heavy lines. Figure 3 also shows the conducting tracks (shown generally at 36) of the circuit including the negative and positive terminals 30 and 32, positioned on the underside of the PCB 34 in broken lines. Figure 4 shows the conducting tracks 36, including the negative and positive terminals 30^* and 32, positioned on the underside of the PCB 34. Figure 4 also shows the relative positions of the (upperside) components of the circuit of the surge suppressor device 10 in parentheses. The conducting tracks 36 of the PCB 34 comprise a conducting track 38 which is a heavier duty track as compared with the remainder of the conducting tracks 36. Accordingly, the conducting track 38 is able to pass a greater amount of the current than the remainder of the conducting tracks 36 without fusing. The conducting track 38 connects the diode D2 in parallel with the resistor Rl and the LED1. Since the largest portion of the remainder of the conducting t^hicks 36 is the conducting track 40 which extends from the negative terminal 30, it is this track which develops greatest heat when a large current due to reverse polarity occurs in the electrical system of vehicle or craft. This causes the conducting track 40 to fuse. In this way, the conducting track 40 acts as a fusible link.

A reduction of width may be provided on the conducting track to allow a faster fuse rate.

However, the fusible link may be provided in the conducting track 42 that connects the LED1 with the resistor Rl, or in the conducting track 44 which connects the resistor Rl with the Zener diode Zl, as previously hereinbefore stated. The diode Dl may be an R.S. Solid State Transient Suppressor 18V part No. 283-277, or equivalent.

The LED1 may glow green when activated and the LED2 may glow red when activated.

The Zener diode Zl may be of 16V, 0.5W rating. The resistor Rl may have a resistance of 560 ohms and be a

0.25W Carbon 5% 560 ohm resistor and the resistor R2 may have a resistanc of 10 ohms and be a 0.25W carbon 5% 10 ohm resistor.

The diode D2 may be an IN4002 diode. The components of the circv t of the surge suppressor device 10 shown in Figure 2 may be soldered into position on the PCB 34 shown in Figures 3 and 4.

The PCB 34 may be single sided, fenolic or fibreglass, silk screened, with no solder mask. The surge suppressor device 10 has a casing 12, which can be seen in Figure 1.

The PCB 34 is located inside the casing 12. The connector leads 20 and 22 extend from the PCB 34 through openings in the casing 12 to the exterior thereof and end in connector rings 28. The casing 12 is provided with a pair of apertures through which the indicators 16 and 18 (in the form of LED1 and LED2), respectively, protrude such that they are visible from the outside of the casing 12. The casing 12 is provided with a pair of mounting lugs 46 (one of which is obscured in Figure 1) at diagonally opposed locations thereof. The mounting lugs 46 are provided with apertures 48 for mounting to a support surface (not shown). The casing 12 may be made of plastics.

The casing 12 may comprise two parts 50 and 52 shown in

Figures 5(a) and 5(b), and Figures 5(c) and 5(d), respectively.

The casing part 50 is provided with recesses 54 on the interior side walls thereof.

The casing part 52 is provided with lug members 56 which extend from the side walls of the casing part 52.

The PCB 34 may be retained inside the casing parts 50 and

52. A pin 58 extends from the interior surface 60 of the casing part 50 to assist in retaining the PCB .34 in position. The lug members 56 may then be engaged in the recesses 54 to thereby connect together the casing parts 50 and 52. Cut-out portions 62 and 64 in the ends of the casing parts 50 and 52 form openings through which the connector leads 20 and 22 may extend when the casing parts 50 and 52 are connected together.

Cut-out portions 66 in the ends of the casing parts 50 and 52 also form an opening when the casing parts 50 and 52 are connected together. The opening formed by the cut-out portions 66 allows a filling material to be poured into the interior of the casing "^* 2. This opening may then be closed off with a cap 68. The viscosity of the filling material must be such as not to allow seepage thereof from the casing 12.

The filling material may be epoxy compound which is poured ^"into the casing 12 until it is substantially 80% full. The manner of operation of the surge suppressor device 10 will now be described.

The surge suppressor device 10 may be mounted onto a suitable surface of a vehicle or craft, e.g. a motor vehicle or marine craft, into whose electrical system the surge suppressor device 10 is to be connected. This can be done by mounting screws, or the like, passing through the apertures 48 in the lugs 46 of the casing part 50 (of the casing "2) and into appropriate apertures in the mounting surface of the vehicle or craft. Alternatively, plast cable ties may be fastened around the casing 12 and onto the high current cables of the elect-leal system of the vehicle or craft.

The surge suppressor device 10 is then connected to the circuit of the electrical system of the vehicle or craft, at a suitable location. One example of a suitable location is across the battery terminals of the battery of the vehicle or craft. The connector lead 20 is connected to the positive terminal of the battery and the connector lead 22 is connected to the negative terminal of the battery. (In this way, the cathode of the high speed transient suppressor diode Dl is connected to the positive terminal of the battery. )

Once the surge suppressor device 10 has been connected to the electrical system of the vehicle or craft, current generated by the battery of the vehicle or craft passes through the surge suppressor device 10.

Under normal operating conditions of the electrical system of the vehicle or craft, current passes through the indicator 16 which is thereby activated. This provides an indication that the surge suppressor device 10 is operational and that the electrical system of the vehicle or craft is operating normally, without surges or spikes in the voltage. If the indicator 16 is provided as the LED1, the LED1 will be illuminated giving a visible indication of the existing normal operating condition. Preferably, the LED1 will glow green.

The transient suppressor 14 prevents passage of current therethrough. The current controller 26 prevents passage of current therethrough such that the indicator 18 is not activated. However, if a transient voltage surge/spike or continuous overvoltage of sufficient size occurs in the electrical system of the vehicle or craft, the current controller 26 will allow current to flow therethrough and through the indicator 18. The indicator 18 could be thereby activated and provide a discernible indication (when the transient voltage surge/spike or overvoltage is above selected levels) that a transient voltage surge/spike or overvoltage condition has occurred in the electrical system of the vehicle or craft.

If the indicator 18 is provided as the LED2, the LED2 could be illuminated giving a visible indication (when the transient voltage surge/spike or overvoltage is above selected levels) of the occurrence of the transient voltage surge/spike or overvoltage condition.

Preferably, the LED2 will glow red.

The transient suppressor 14 will continue to prevent passage of current therethrough.

Accordingly, when a transient surge/spike condition occurs the transient suppressor 14 suppresses or limits such transient voltage surges/spikes in the electrical circuit of the vehicle or craft and the indicator 18 could be activated and provide a discernible indication (when the transient voltage surge/spike is above a selected level) of the occurrence of the transient voltage surge/spike condition since the current controller 26 will allow passage of current therefrom above a selected voltage. Similarl". in the case of an overvoltage condition the transie suppressor 14 -acts to suppress such overvoltage in accordance with its rating. Further, in the case of an overvoltage condition above a selected level, the indicator 18 provides a discernible indication of the overvoltage condition.

It is possible that some transient voltage surges/spikes . will be at such high speed levels that they will not result in the indicator 18 being activated for a sufficient time to provide a discernible indication, to the naked eye. However, a series of transient voltage surges/spikes at such high speed levels could be visible to the naked eye. In any case, the second embodiment of the present invention to be later hereindescribed provides means for making even these transient voltage surges/spikes at high speed levels discernible to the naked eye.

The reverse polarity response means 24 responds to a reverse polarity condition in the circuit of the electrical system of the vehicle or craft. Such a reverse polarity condition occurs, for example, if the battery leads of the vehicle or craft are connected in reverse. When a reverse polarity condition occurs in the electrical system of the vehicle or craft, high current flows through the diode D2 and the fusible device 28 (e.g. the fusible link) causing it to fuse, or open circuit. When this occurs no power is able to flow through the first indicator 16, so it is deactivated.

When the indicator means 16 is in the form of the LEDl, the LED1 ceases to the illuminated. In this way, positive indication of polarity reversal is provided.

The provision of the reverse polarity response means 24 and the positive indication thereof provides security for the equipment manufacturer in the event of abuse of the vehicle's or craft's electrical system circuitry by inadvertent or deliberate reversing of battery leads thereby damaging sensitive electronic componentry. Figure 6 shows a circuit diagram of a surge suppressor device 10' of a second embodiment of the present invention. ^r *.e surge suppressor device 10' incorporates components corresponding to the components of the surge suppressor device 10 of the first embodiment along with additional components. Like reference numerals and lettering are used for corresponding parts in the drawings of the first and second ibodiments. However, to facilitate ease of distinguishing between the two embodiments, the reference numerals and lettering of the second embodiment are followed by a superscript.

The surge supp„. ^sor device 10' is able to "trap" transient surges/spikes and provide extended indication of their occurrence, including these at high speed levels as previously indicated. The surge suppressor device 10' comprises a transient suppressor 14', an indicator 16' and a another indicator 18' .

The transient suppressor 14', indicator 16' and indicator 18' are connected between a pair cf connector leads 20' and 22'. As shown in Figure 6, the connector lead 20' is a

"positive" lead and the-connector lead.22' is a "negative" lead. The connector lead 20' is connected to the positive terminal 32'and the connector lead 22' is connected to the negative terminal 30'. The surge suppressor device 10' may further comprise reverse polarity response means 24' which responds to a reverse polarity condition. The surge suppressor device 10' also comprises extended transient indication means shown generally at 70'.

The indicator 18' is connected with a current controller 26' via the extended transient indication means 70'. The extended transient indication means 70' comprises a sensor and extender means 72' along with extended transient indication determining means 74' which operate on the indicator 18' .

The nature of the transient suppressor 14', indicator 16', indicator 18', reverse polarity response means 24' and current controller 26* may be of the same form as the corresponding components of the surge suppressor device 10 of the first embodiment as previously hereinbefore described.

A resistor Rl is provided in series with the LEDl'and a resistor R2' is provided in series with the Zener diode Zl'. This is similar to the arrangement of the first embodiment.

The fuse device 28' of the reverse polarity response means 24' may be located in similar manner to the reverse polarity response means 24 of the first embodiment. The sensor and extender means 72^! may comprise an I.C. chip IC1 and the extended transient indication determining means 74' may comprise a resistor R5' and a capacitor C2' . A transistor 76' has its base connected to the Zener diode Zl' via the resistor 22'; the collector of the transistor 76' is connected o the I.C chip ICl; and, the emitter of the transistor 76' is connected to the negative terminal

30' .

The LED2' is connected to the I.C. chip ICl' via a resistor R4' .

The I.C. chip ICl' is connected to the resistor R5' and the capacitor C2' which are connected across the negative and positive terminals 30' and 32'.

The capacitor Cl' connects pin 5 of the IC chip ICl' to the negative rail for circuit stability as required in I.C chip

ICl' specifications.

The diode Dl' , diode D2' Zener diode 21' and resistor Rl^* may be of the same types as those of the surge suppressor device 10 of the first embodiment as previously hereinbefore described.

The I.C chip ICl' may be an LM555 Timer Chip.

The transistor 76' may be a BC 548 transistor.

The resistors Rl' , R2, R3' , R4' and R5* may be 560 ohm,

1000 ohm, 560 ohm and 470 ohm resistors, respectively. The capacitors Cl' and C2' may be O.Olmf and O.lmf (green) capacitors, respectively.

The components of the circuit of the surge suppressor device 10' shown in Figure 6 may be soldered into position on a PCB (not shown) in a manner similar to that described with reference to the PCB 34 of the first embodiment.

The surge suppressor device 10' may be provided with a casing (not shown) of the same type as the casing 12 of the first embodiment.

The manner of operation of the surge suppressor device 10' will now be described.

The surge suppressor device 10' may be mounted onto a vehicle or craft and connected to is electrical system circuit in the same manner as previously described for the surge suppressor device 10 of the first embodiment.

The operating conditions of the surge suppressor device 10' are shown in functional block diagram form in Figure 7. Under normal conditions the surge suppressor device 10' operates in the same manner as the surge suppressor device 10 of the first embodiment.

If a transient voltage surge/spike or continuous overvoltage of sufficient size occurs in the electrical system of the vehicle or craft, the current controller 26' will allow current to flow therethrough and into the base of the transistor 76'. The transistor 76' then switches on which pulls pin 2 of the I.C. chip ICl' low causing the output on pin 3 to go high to power the indicator 18' (LED2^*). In this way, the I.C chip ICl' senses and extends the "ON" time of the indicator 18' to make the transient voltage surge/spikes visible for a longer time. The indicator 18' provides a discernible indication (when the transient voltage surge/spike or overvoltage is above selected levels) that a transient voltage surge/spike or overvoltage condition has occurred in the electrical system of the vehicle or craft.

The voltage at which the current controller 26' conducts is greater than the normal circuit voltage and less than the operating voltage of the surge suppressor 14'. Thus, the activation of the indicator 18' is triggered by the difference in the voltage of the current controller 26' (i.e. Zener diode Zl', 16 volts) and the transient suppressor 14' (i.e. Diode Dl',18 volts). In this way, the indicator 18' provides indication of the presence of voltages in excess of normal acceptable operating levels. This is also the case in the surge suppressor device 10 of the first embodiment. If the indicator 18' is provided as the LED2' , the LED2' will be illuminated for a selected time giving a visible indication (when the transient voltage surge/spike or overvoltage is above selected levels) of the occurrence of the transient voltage surge/spike or overvoltage condition. Preferably, the : ^*D2' will glow red.

The duration of illumination of the LED2' is determined by the capacitance of the capacitor C2^; and resistance of the resistor R5' .

Accordingly, when a transient surge/spike condition occurs the transient suppressor 14' suppresses or limits such transient voltage surges/spikes in the electrical circuit of the vehicle or craft and the indicator 18' is activated and will provide a discernible indication for an extended d tion (whe - the transient voltage surge/spike is above a st .cted level) of the occurrence of the transient voltage surge/spike condition since the current controller 26' will allow passage of current therethrough above a selected voltage. Similarly, overvoltage conditions will also be indicated by the indicator 18' The surge suppressor device of the present invention limits the transient voltage excursions on the power supply to within selected limits. For a 12 volt power supply, such as in motor vehicle or marine craft, the surge suppressor device 10 may, preferably, limit the transient voltage excursions on the vehicle or craft electrical system power supply to approximately + 18 volts and -2 volts. The transient suppressor 14, 14' limits the voltage from positive to negative to its rated turn-on voltage. For a 12 volt power supply, this may be substantially 18 volts. Further, the transient suppressor 14,14' also prohibits the voltage which may be present on the positive supply from ever becoming lower than 2 volts below the negative supply (in a 12 volt power supply system). This prevents the potentially destructive "reverse-biasing" of any electronics components connected to the power supply in an electrical circuit. Transient voltages producing surges/spikes can result from different causes. By way of example, the following are given.

When a "jump started" battery is disconnected from a slave battery, either accidentally or on completion of engine starting, a collapse of voltage in the system can occur which may cause high voltage surges/spikes to be generated in any inductive coils connected at the time, e.g. solenoids, relays, electro-magnetic clutches, etc. Voltage surges/spikes may also be caused by running the vehicle or craft engine with a nearly open circuit battery by the alternator running into the almost no-load battery.

Voltage surg„-./spikes may also occur by operating the air conditioner switch (a highly inductive clutch coil).

When the engine of a vehicle having an open circuit battery is run, the transient voltage levels may reach a peak of 35 volts with consistent repetitive peaks up to 65 volts.

An open circuit battery condition may, for example, result from loose, corroded battery terminals or battery failure.

The type of batte failure usually involved is cell plate breakage caused by shock or old age.

The surge suppressor device of the present invention suppresses or limits transient voltages to levels where the potential for damage to sensitive electronic components is minimized. Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.

Claims

1. A surge suppressor device characterized in that it comprises transient suppressor means to suppress cr limit transient voltages in a circuit to which said surge suppressor device is connectable and indicator means able to indicate when a transient voltage or an overvoltage condition above selected levels occurs in said circuit.

2. A surge suppressor device according to claim 1, characterized in that it further comprises current controller means to prevent passage of current below said selected voltage levels.

3. A surge suppressor device according to claim 2, characterised in that said indicator means is activated when said current controller means allows passage of current therethrough above said selected voltage levels such that said indicator means provides indication that a said transient voltage or overvoltage condition has occurred in said circuit.

4. A surge suppressor device according to any one of claims 1 to 3, characterized in that it further comprises second indicator means which is activated when current flows through said surge suppressor device to provide indication of current flow through said surge suppressor device and that normal operating conditions exist in said circuit.

5. A surge suppressor device according to claim 4, characterized in that it further comprises reverse polarity response means which is able to respond to a reverse polarity in said circuit and cause an indication thereof to be given .

6. A surge suppressor device according to claim 5, characterized in that said reverse polarity response means comprises fuse IT -s and diode means suclr that when a reverse polarity condition occurs in said circuit said diode allows current flow therethrough and said fuse means responds to said reverse polarity condition and fuses to cause said second indicator means to be deactivated to provide indication of said reverse polarity condition.

7. A surge suppressor device according to any one of claims 1 to 6, characterized in that it further comprises extended transient indication means to extend the duration of activation of said indicator means when a transient voltage condition above a selected level occurs in said circuit.

8. A surge suppressor device according to claim 7, characterized in that said extended transient indication means comprises sensor and extender means and extended transient indication determining means, wherein said sensor and extender means receives and senses a signal when a transient voltage condition above the selected level occurs and activates said indicator means and said extended transient indication d-r -ermining means determines the duration of activation of said i^* "-icator means.

9. A surge suppressor .device acccrc. Ing to any one of claims 2 to 8, characterized in that said current controller means comprises a Zener diode which allows current to flow such that said indicator means is activated. _ _

10. A surge suppressor device according to claim 9, characterized in that it further comprises transistor means and said sensor and extender means comprises an IC chip, wherein when a transient voltage or overvoltage condition above said selected levels occurs said Zener diode conducts current to the base of said transistor means through first resistor means and said transistor means sends a signal to said IC chip which then sends a signal to activate said indicator means through second resistor means.

11. A surge suppressor device according to any one of claims 8 to 10, characterized in that said extended transient indication determining means comprises a resistor and a capacitor which are connected to said sensor and extender means.

12. A surge suppressor device according to any one of claims 6 to 11, characterized in that said fuse means is provided in the circuit line of said surge suppressor device in which said second indicator means is positioned such that it fuses in response to a reverse polarity condition in said circuit.

13. A surge suppressor device according to any one of claims 6 to 12, characterized in that said surge device is provided on a PCB having conducting tracks between the components thereon, wherein said fuse means comprises a fusible link means in said conducting tracks such that the conducting track of said circuit in which said second indicator means is positioned fuses in response to a reverse polarity condition in said circuit.

14. A surge suppressor device according to claim 13, characterised in that said fusible link means is formed by providing the conducting track containing said diode means as a heavy duty track as compared with the remaining conducting tracks.

15. A surge suppressor device according to any one of claims 1 to 14, characterized in that said transient suppressor means comprises a diode.