Relays are simple electronic switching devices that are commonly found in household electrical appliances and motor vehicles. Indeed some of the first computers developed employed relays to implement the required Boolean gates.

A typical relay 1, as presented in Figure 1, is a simple electromechanical switch that comprises an electromagnet 2, an armature 3, a spring 4 and a set of electrical contacts 5. The relay 1 can be seen to consist of two separate and completely independent circuits. In this example the first circuit comprises a switch 6 while the second comprises a light bulb 7.

The first circuit is used to provide power for the electromagnet 2. When the switch 6 is closed the electromagnet 2 generates an electric field that acts to attract the armature 3. When the attractive force of the electric field is strong enough to overcome the bias force of the spring 4 the armature 3 moves so as to complete the second circuit. Therefore, closing the switch 6 in the first circuit effectively acts to turn on the light bulb 7. On opening the switch 6 the electric field generated by the electromagnet 2 collapses such that the bias force of the spring 4 acts to return the armature 3 back to it's original position.

In practice a relay 1 can be employed whenever a large power is required to be safely switched. Typically an electromagnet 2 can be energised using 5V and 50mA (250mW) while an armature circuit can support 120V AC at 2A (240W). In a motor vehicle the battery typically provides a 12V supply voltage therefore most circuits within the motor vehicle require to draw a large current.

Relays 1 are designed so as to have standard pinouts.

Figure 2 depicts one such standard where five pins are labelled with the numbers 85,86, 87,87a and 30 respectively, with the 30 pin isolated as shown such that all the pins can be readily identified.

The 85 and 86 pins are those associated with the circuit containing the electromagnet 2. The 30,87 and 87a pins are associated with the circuit containing the armature 3. In effect 87 and 87a are the two contacts to which the 30 pin connects. In the relay 1 of Figure 1, when the electromagnet 2 is not activated the 87a pin is connected to the 30 pin. When current is applied to the electromagnet 2, as described above, the 87 pin then becomes connected to the 30 pin therefore causing the light bulb 7 to be illuminated.

In an alternative embodiment of relay switch (not shown) instead of the relay switch acting to turn power on and off it acts to re-route power between the 87a pin and the 87 pin in a similar fashion to that described above.

Therefore, if light bulbs are incorporated in both of the associated circuits the energising of the electromagnet would act to turn the light bulb associated with the 87a pin off while turning on the light bulb associated with the 87 pin. Switching off the power to the electromagnet would cause the reverse process to take place such that the bulb associated with the 87a pin would again become illuminated while that associated with the 87 pin would again be switched off.

As with all electrical components relays 1 are subject to physical damage. Power surges in supply circuits or adverse mechanical contact can cause such physical damage. Practically it is often difficult to determine whether it is the relay 1 itself that has been damaged or a component of the supply circuitry. A method of trial and error must then be employed in order to track down the source of such a fault. Such methods can be very time consuming especially within systems that employ a number of relays 1.

A solution attempted in the Prior Art is to employ a test light device. However, to operate correctly such test lights require to be properly grounded and thereafter a probe requires to be located so as to make a good electrical contact with the appropriate source being tested. Therefore, the proper employment of the test light requires an inherent skill and understanding of the relay 1 and the electrical circuit in which the relay 1 is a component.

It is an object of at least one aspect of the present invention to provide a relay testing apparatus that provides a means for testing a relay and an electrical circuit in which the relay is a component.

It is a further object of at least one aspect of the present invention to provide a relay testing apparatus that can be employed with minimal understanding of a relay or an electrical circuit in which the relay is a component.

Within the following aspects of the present invention a switch is a mechanical means that moves between an open and closed position wherein when in the closed position the switch completes an electric loop within which the switch is a component.

According to a first aspect of the present invention there is provide a relay testing device for testing a relay comprising a main body, a means for connecting to a relay, an electronic control circuit and a power supply.

Most preferably the means for connecting to a relay comprises a socket suitable for receiving a pinout from a standard relay.

Preferably the power supply provides the required power for energising the relay.

Preferably the electronic control circuit comprises a first electronic loop employed to test whether there exists a current output from a pinout corresponding to the relay in an unenergised position.

Preferably the first electronic loop comprises a first indicator, wherein the first indicator is activated when a current flows from the pinout corresponding to the relay in an unenergised position.

Optionally the first electronic loop comprises a first switch.

Most preferably the electronic control circuit comprises a second electronic loop employed to test whether there exists a current output from a pinout corresponding to the relay in an energised position.

Preferably the second electronic loop comprises a second switch wherein on activating the second switch an energising current is supplied to the relay.

Preferably the second electronic loop further comprises a second indicator wherein the second indicator is activated when a current flows from the pinout corresponding to the relay in an energised position.

Preferably one or more of the indicators comprises a visible light source. Alternatively or in addition one or more of the indicators may comprise an audible alarm.

According to a second aspect of the present invention there is provide a relay testing device, for testing an electrical circuit in which a relay is a component part, comprising a main body, a means for connecting to a relay socket and an electronic control circuit.

Most preferably the means for connecting to a relay socket comprises a plug wherein the plug comprises a standard relay pinout.

Preferably the electronic control circuit comprises a first electronic loop employed to test whether the electrical circuit is providing a current of the correct magnitude to an armature circuit of the relay.

Preferably the first electronic loop comprises a first indicator, wherein the first indicator is activated when a current flows within the first electronic loop.

Preferably first electronic loop comprises a fuse.

Optionally the first electronic loop comprises a first switch.

Preferably the electronic control circuit further comprises a second electronic loop employed to test whether a current requiring device supplied from a pinout corresponding to the relay in an unenergised position is in good working order.

Preferably the second electronic loop comprises a second switch, wherein on closing the second switch the current requiring device supplied from the pinout corresponding to the relay in the unenergised position is activated.

Optionally the second electronic loop comprises a second indicator, wherein the second indicator is activated when a current flows within the second electronic loop.

Preferably the electronic control circuit further comprises a third electronic loop employed to test whether a current requiring device supplied from a pinout corresponding to the relay in an energised position is in good working order.

Preferably the third electronic loop comprises a third switch, wherein on closing the third switch the current requiring device supplied from the pinout corresponding to the relay in the energised position is activated.

Optionally the third electronic loop comprises a third indicator, wherein the third indicator is activated when a current flows within the third electronic loop.

Preferably the electronic control circuit further comprises a fourth electronic loop employed to test whether a switch used to control the energising current of the relay, as provided by the electrical circuit in which the relay is a component part, is in good working order.

Most preferably the fourth electronic loop comprises a fourth indicator connected across the current supply to an electromagnet circuit of the relay, wherein the fourth indicator is activated when a current flows within the fourth electronic loop.

Preferably one or more of the indicators comprises a visible light source. Alternatively or in addition one or more of the indicators may comprise an audible alarm.

According to a third aspect of the present invention there is provide a relay testing device for use with a relay and an associated electrical circuit in which a relay is a component part comprising a main body, a means for connecting to a relay socket, a means for connecting to a relay and an electronic control circuit.

Most preferably the means for connecting to a relay socket comprises a plug comprising a standard relay pinout.

Most preferably the means for connecting to a relay comprises a socket suitable for receiving a pinout from a standard relay.

Preferably the relay testing device further comprises a power supply.

Optionally the power supply provides the required power for energising the relay.

Preferably the electronic control circuit comprises a first electronic loop employed to test whether the electrical circuit is providing a current of the correct magnitude to an armature circuit of the relay.

Preferably the first electronic loop comprises a first indicator, wherein the first indicator is activated when a current flows within the first electronic loop.

Preferably first electronic loop comprises a fuse.

Optionally the first electronic loop comprises a first switch.

Preferably the electronic control circuit further comprises a second electronic loop employed to test whether a current requiring device supplied from a pinout corresponding to the relay in an unenergised position is in good working order.

Preferably the second electronic loop comprises a second switch, wherein on closing the second switch the current requiring device supplied from the pinout corresponding to the relay in the unenergised position is activated.

Optionally the second electronic loop comprises a second indicator, wherein the second indicator is activated when a current flows within the second electronic loop.

Preferably the electronic control circuit further comprises a third electronic loop employed to test whether a current requiring device supplied from a pinout corresponding to the relay in an energised position is in good working order.

Preferably the third electronic loop comprises a third switch, wherein on closing the third switch the current requiring device supplied from the pinout corresponding to the relay in the energised position is activated.

Optionally the third electronic loop comprises a third indicator, wherein the third indicator is activated when a current flows within the third electronic loop.

Preferably the electronic control circuit further comprises a fourth electronic loop employed to test whether a switch used to control the energising current of the relay, as provided by the electrical circuit in which the relay is a component part, is in good working order.

Most preferably the fourth electronic loop comprises a fourth indicator connected across the current supply to an electromagnet circuit of the relay, wherein the fourth indicator is activated when a current flows within the fourth electronic loop.

Preferably the electronic control circuit further comprises a fifth electronic loop employed to test whether there is a current output from a pinout corresponding to the relay in an unenergised position.

Preferably the fifth electronic loop comprises a fifth indicator, wherein the fifth indicator is activated when a current flows from the pinout corresponding to the relay in an unenergised position.

Optionally the fifth electronic loop comprises a fourth switch. Most preferably the electronic control circuit further comprises a sixth electronic loop employed to test whether there is a current output from a pinout corresponding to the relay in an energised position.

Preferably the sixth electronic loop comprises a fifth switch wherein on activating the fifth switch an energising current is supplied to the relay.

Most preferably the sixth electronic loop comprises a sixth indicator wherein the sixth indicator is activated when a current flows from the pinout corresponding to the relay in an energised position.

Preferably one or more of the indicators comprises a visible light source. Alternatively or in addition one or more of the indicators may comprise an audible alarm.

According to a fourth aspect of the present invention there is provided a method for testing a relay comprising the steps of: 1. Connecting the relay to a connection means of a relay testing device in accordance with the apparatus of the first aspect of the present invention; 2. Energising the relay ; 3. Testing to determine whether a current flows from a pinout corresponding to the relay in an energised position; Optionally the method for testing the relay further comprises testing to determine whether a current flows from a pinout corresponding to the relay in an unenergised position; Most preferably the relay is energised by the closing of a switch.

Preferably a test is positive if an indicator is activated.

Preferably the activation of an indicator comprises the illumination of a visible light source. Alternatively or in addition the activation of an indicator comprises the sounding of an audible alarm.

According to a fifth aspect of the present invention there is provided a method for testing an electrical circuit in which a relay is a component part comprising the steps of: 1. Connecting a relay testing device, in accordance with the apparatus of the second aspect of the present invention, to the electrical circuit; 2. Testing whether the electrical circuit provides a current of the correct magnitude to an armature circuit of the relay ; 3. Testing whether a current requiring device supplied from a pinout corresponding to the relay in an energised position is in good working order; 4. Testing whether a switch used to control the energising current for the relay, as provided by the electrical circuit, is in good working order ; Optionally the method for testing an electrical circuit in which a relay is a component part further comprises testing whether a current requiring device supplied from a pinout corresponding to the relay in an unenergised position is in good working order.

Most preferably a test is initiated by the closing of a switch.

Preferably a test is positive if an indicator is activated.

Preferably the activation of an indicator comprises the illumination of a visible light source. Alternatively or in addition the activation of an indicator comprises the sounding of an audible alarm.

According to a sixth aspect of the present invention there is provided a method for testing a relay and an electrical circuit in which a relay is a component part comprising the steps of: 1. Testing the electrical circuit in which a relay is a component part in accordance with the method of the fifth aspect of the present invention; 2. Testing the relay in accordance with the method of the fourth aspect of the present invention.

Example embodiments of the present invention, which are given by way of example only, are described with reference to the following figures: Figure 1 presents a schematic representation of a relay ; Figure 2 presents a standard pinout for the relay of Figure 1 ; Figure 3 presents a schematic representation of a relay testing device ; Figure 4 presents a circuit diagram of the relay testing device of Figure 3.

Referring to Figure 3 a schematic representation of a relay testing device 8 is generally depicted. The relay testing device 8 can be seen to comprise a relay plug 9 and a main box 10 connected together by an electrical cable 11. Mounted on the main box 10 are a relay socket 12, three switches 13, 14 and 15, three lamps 16, 17 and 18 and an audible alarm 19.

Figure 4 presents a circuit diagram of the relay testing device 8. As can be seen an electronic circuit 20 is housed within the main box 10 that is employed to control the relay testing device 8. An external connection 21 is also incorporated with the electronic circuit 20 so as to provide a means for supply independent power to the relay testing device 8, if required.

A description now follows of how the relay testing device 8 is deployed in order to test a relay 1 and an associated electrical circuit within a motor vehicle.

The same process can equivalently be carried out for any relay and associated electrical circuit. Before commencing all the three switches 13,14 and 15 are set to be in their open or off position.

The first step is for the relay 1 to be removed from the vehicle relay socket (not shown). For example the relay 1 can relate to the headlights, rear demister or horn circuitry, to name but a few of the relay electrical circuits found within the vehicle. The relay plug 9 is then inserted into the relevant vehicle relay socket.

At this stage the relay testing device 8 checks to see if there is a current of the correct magnitude flowing in the electrical circuit of the motor vehicle that supplies the current to the electromagnet 2 of the relay 1. This is achieved by checking to see if there is power being supplied to the 30 pin of relay plug 9 and that the 85 pin of relay plug 9 is correctly grounded. A fuse 22, of an appropriate power rating, is located in this circuit in order to protect the relay testing device 8 from power supplies above a threshold safety value.

If the correct power rating is being supplied to the 30 pin of the relay plug 9 and the 85 pin of the relay plug 9 is correctly grounded then a voltage drop across the first lamp 16 results in it being illuminated. However, if there is no power supply, or the power supply is of a level greater than the power rating of the fuse 22, such that the fuse 22 has blown, then the first lamp 16 is not illuminated. Therefore, the first lamp 16 indicates to the operator whether or not there is a fault in the electrical supply circuit of the motor vehicle.

The second step of the testing process is to test the whether the vehicles power supply is reaching the 87 pin of the relay plug 9. This is achieved by employing the electrical circuit loop that incorporates the first switch 13. On closing the first switch 13 an electrical connection is made between the 30 pin and the 87 pin of the relay plug 9 such that power should be provided to the vehicle apparatus connected to the 87 pin. For example if it is the headlight circuitry, and associated relay 1, that is being tested then the headlights should be activated so indicating that they are in good working order. If this is not the case then the operator has located a fault in the motor vehicles electrical circuit for the headlights.

The third step of the testing process is to test the if the vehicles power supply is reaching the 87a pin of the relay plug 9. This is not always applicable as often this pin is simply employed as the off position for a circuit, as was the case for the relay 1 outlined in Figure 1. However, if required this test is similar to that described above in relation to the headlight circuit of the motor vehicle. Here the electrical circuit loop that incorporates the second switch 14 is employed. On closing the second switch 14 an electrical connection is made between the 30 pin and the 87a pin of the relay plug 9 such that power should be provided to any apparatus connected to the 87a pin, thus activating it as appropriate.

The fourth step of the testing process is to check whether the activating power for the relay switch is in fact reaching the relay 1 i. e. is the circuit connecting the 85 pin and the 86 pin of the relay plug 9 operating correctly. By operating the vehicle function switch the switching power for the relay 1 should pass between these pins thus providing a voltage drop across the audible alarm 19 causing it to sound. If the audible alarm 19 does not sound then the operator has located a fault in the motor vehicles electrical circuit for the headlights or other equivalent electrical circuit being tested.

The fifth step of the testing process involves the testing of the relay 1 itself. The relay 1 is therefore located in the relay socket 12 of the relay testing device 8. Initially with the third switch 15 in the open position no power is being provided to energise the electromagnet 2 of the relay 1. Therefore, the armature 3 is in contact with the 87a pin of the relay 1. For the aforementioned headlight circuit this corresponds to the lights being off so no power is supplied to the 87a pin.

In this case there would be no voltage drop across the second lamp 17 and so it would not be illuminated.

The final step for the operator is to close the third switch 15. On closing this switch a current flows between the 85 pin and the 86 pin of the relay 1 and so the associated electromagnet 2 is energised. This causes the armature 3 to switch between the 87a pin and the 87 pin positions. Therefore, a voltage drop is now experienced across the third lamp 18 that results in it becoming illuminated. Therefore, the operator would know that power is reaching the 87 pin of the relay 1 and that it is in good working order.

The relay testing device 8 can be readily employed with the alternative designed relays. The relay design may be such that it switches power between the 87 and 87a pins, rather than switching power on and off at the 87 pin, as described above for the motor vehicle headlight circuit.

Therefore, on placing such a relay in the relay socket a voltage drop would be experienced across the second lamp 17 causing it to be illuminated at this time. Thus an operator would know that power is reaching the 87a pin of the relay and that this side of the switch is in good working order.

Now on closing the third switch 15 a current again flows between the 85 pin and the 86 pin of the relay and so the associated electromagnet is energised. This causes the armature to again switch between the 87a pin and the 87 pin positions. Therefore, the voltage drop across the second lamp 17 is no longer present and so it is switched off while a voltage drop is experienced across the third lamp 18 resulting in it becoming illuminated. An operator would now know that power is reaching the 87 pin of the relay and that it is in good working order.

The external connection 21 provides for the relay testing device 8 to be used to test a relay independently of any associated electrical circuit. By connecting the external connection to a battery (not shown) or similar power source the relay can simply be located in the relay socket 12 and thereafter tested as described above.

In an alternative embodiment of the present invention the relay testing device comprises two separate modular units that work in independence of each other. A first modular unit comprises the testing apparatus for testing the relay in accordance with the first aspect of the present invention. A second modular unit comprises the testing apparatus for the testing of an electrical circuit in which the relay is a component part, in accordance with the second aspect of the present invention.

An advantage of aspects of the present invention is that they provide a relay testing apparatus that allows for the testing of a relay and an electrical circuit in which the relay is a component. In addition the described relay testing apparatus requires only a minimal understanding of the workings of a relay or an electrical circuit in which the relay is a component.

A further advantage of aspects of the present invention is that they provide a relay testing apparatus that can be connected to an external power source such that it may be employed to test relays independently of any associated electrical circuit. This would be particularly useful where a large number of used and unused relays are required to be tested in order to determine which ones are of further use to an operator.

Although exemplary embodiments of the present invention have been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications or alterations to the invention described herein may be made, none of which depart from the invention as defined in the appended claims. All such changes, modifications, and alterations should therefore be seen as being within the scope of the present invention.