WO2006065128A1

WO2006065128A1 - Earth leakage circuit breaker

Info

Publication number: WO2006065128A1
Application number: PCT/NL2005/050023
Authority: WO
Inventors: Ronaldus Hendrikus Maria Niehoff
Original assignee: Eaton Electrics BV
Current assignee: Danfoss Power Solutions II BV
Priority date: 2004-10-26
Filing date: 2005-10-26
Publication date: 2006-06-22
Anticipated expiration: 2007-04-26
Also published as: PT1805861E; EP1805861A1; NL1027341C2; ATE516619T1; SI1805861T1; EP1805861B1; ES2369024T3; DK1805861T3; PL1805861T3

Abstract

Earth leakage circuit breaker (90) for use in a safety switch. The circuit comprises a detection device (91) for detecting an earth leakage current in the electric circuit of the safety switch, an actuator element (93) for breaking the electric circuit of the safety switch and an actuator circuit (98), connected to the detection device (91) and the actuator element (93), for energising the actuator element (93) in the event of an earth leakage current in excess of a predefined threshold being detected. The actuator circuit (98) is provided with a selection connection (97) for selecting the type of actuator element (93) mat has to be actuated.

Description

Earth leakage circuit breaker

Field of the invention

The present invention relates to an earth leakage circuit breaker for use in a safety switch.

State of the art

An earth leakage circuit breaker of this type is generally used in an earth leakage safety device. An earth leakage safety device can be fitted with various types of actuator which break one or more contacts in the event of an earth leakage current being detected. Different types of actuator circuit are required for all the different types of actuator. A wide variety of actuator circuits must therefore always be available in order to manufacture a range of products.

Summary of the invention

The present invention seeks to provide an earth leakage circuit breaker that can be used for various types of actuator which can be used in the earth leakage protection device.

According to the present invention, an earth leakage circuit breaker of the type defined in the preamble is provided which comprises a detection device for detecting an earth leakage current in the electric circuit of the safety switch, an actuator element for breaking the electric circuit of the safety switch, an actuator circuit, connected to the detection device and the actuator element, for energising the actuator element in the event of an. earth leakage current in excess of a predefined threshold being detected, where the actuator circuit is provided with a selection connection for selecting the type of actuator element that has to be actuated. In this way an actuator circuit can be used for various types of actuator, with the result that an extensive degree of standardisation is achieved within a product range.

In one embodiment of the present invention, the type of actuator element is a solenoid type and the actuator circuit enables the actuator element by means of a thyristor stage. The thyristor stage can be housed in the actuator circuit, in the actuator itself, or as a stand-alone module. hi a further embodiment, the type of actuator element is a latch type and the actuator circuit enables the actuator element by means of an open collector stage. This open collector stage can easily be housed in the actuator circuit

In yet another embodiment, the type of actuator element is a piezo element and the actuator circuit enables the actuator element by means of a high-voltage output stage. The high-voltage output stage can also be integrated in the actuator circuit or be provided as a stand-alone module.

The actuator circuit in one embodiment is comprised in an integrated circuit, for example in an ASIC (application-specific integrated circuit). This method enables large numbers of actuator circuits to be manufactured at low cost

In a further embodiment, the actuator circuit is comprised in an enclosure for surface mounting. Such an SMD version (surface-mounted device) of the actuator circuit is easy to position and takes up little space. As an example, an SO8 enclosure is suitable which takes up even less space. As an alternative embodiment, the actuator circuit can be manufactured in the form of an integrated circuit which is suitable for flip-chip assembly. The bare chip then has raised solder locations or solder bumps and can be mounted on a substrate with the underside facing upwards (hybrid printed circuit board). This embodiment requires even less space.

In a further embodiment, the actuator circuit has a supply circuit where said supply circuit is detachably connected to a phase terminal and a neutral terminal of the safety switch. By connecting the supply circuit to the safety circuit status it is possible to conduct tests such as earth resistance tests or test voltage tests without the risk of damaging the actuator circuit itself.

In yet another embodiment, the actuator circuit has a supply circuit where said supply circuit has a capacitive input impedance so that Hie correct insulation resistance is measured when testing the earth resistance with a DC voltage, ϊn. this embodiment, the actuator circuit does not then have to be electrically isolated from the switched connections.

Brief description of the drawings

The present invention will now be discussed in more detail on the basis of a number of illustrative embodiments, with reference to the appended drawings, in which

Fig. 1 shows a simplified block diagram of an embodiment of an actuator circuit according to the present invention. Detailed description of illustrative embodiments .

As shown in Fig. 1, the earth leakage circuit breaker 90 comprises a detection device

91 which, in conjunction with a detector coil 9, detects whether an (excessive) earth leakage current is occurring in the electric circuit that is connected to an output phase terminal 12 or an output neutral terminal 21. In the electric circuit, moving contacts 7 and 19 of a switch in which the earth leakage circuit breaker 90 can be used are also shown in the block diagram in Fig. 1. Hie earth leakage circuit breaker 90 also comprises a supply

92 which is connected to trailing supply contacts 94, 95. The trailing supply contacts close and open synchronously with the main contacts 7 and 19. As a result, the entire earth leakage circuit breaker 90 will be de-energised as soon as the switch 50 is switched off. This has the benefit of enabling the rest of the safety switch 50 to be exposed to high voltages (earth resistance tests at, for example, > 1000 Vdc, or test voltage tests at > 500 Vac) without the necessity for further measures.

An actuator circuit 98 is connected to the detection device 91 and the supply 92 and is set up to energise an actuator 93 to switch off the switch 50. As shown in the block diagram, the actuator 93 acts at the moving contacts 7 and 19 in the phase and neutral terminals, respectively.

The actuator 93 can be an actuator of various types. The use of a solenoid-based actuator in which a generated magnetic force operates a mechanical contact mechanism is known in the art. Actuators that release a stored quantity of energy with the aid of a mechanical latch, for example a moving contact pretensioned by a spring, as a result of which the circuit can be broken with predefined characteristics, are also known in the art Finally, actuators which utilise the mechanical force that can be generated with the aid of piezo elements are also known in the art Each of these types of actuator uses its own, therefore different, means of actuating the actuator 93. A solenoid-based actuator 93 is generally actuated with the aid of a thyristor stage. The mechanical operating force of a solenoid has to be entirely generated by means of the magnetic force generated using a magnetic field. The relatively high mechanical operating force has to be generated by a relatively large magnetic field as a result of which, in conjunction with the design of a solenoid, a relatively large current also flows through the circuit which can be controlled with such a thyristor stage or comparable electronic amplifier. A latch-based actuator 93 is usually adequate with actuation based on an open collector stage since the required (high) mechanical force is generated by a pretensioned stored energy device, for example in the form of a spring, but only a relatively small magnetic field with a corresponding small current is required to unlatch it. An actuator based on piezo elements requires a relatively high voltage but only a small capacitive current. This type of actuator is generally actuated by a voltage-increasing output stage.

For reasons of efficiency, the actuator circuit 98 has been designed such that it can actuate several types of actuator 93 (including the types discussed above). To that end, the actuator circuit 98 is provided with one or more selection connections 97. By means of these selection connections 97 one or more sections of the actuator circuit can be switched off or on in a manner known in the art (for example, by connecting two connections 97 together or connecting one connection 97 to earth or the supply voltage).

The actuator circuit 98 in one embodiment is manufactured as an integrated circuit such as an application-specific integrated circuit (ASIC). This enables a multiplicity of actuator types 93 to be actuated in an earth leakage circuit breaker using just one type of IC (ASIC). This offers many benefits at a logistical level.

With the latch-type actuator, a single open collector stage on the ASIC is sufficient. The solenoid-type actuator requires an output on the ASIC to actuate the external thyristor which in turn actuates the solenoid. The two ASIC outputs have different signal levels and output characteristics. One option is to produce the ASIC such that both types of output circuit are present on the chip and are available by means of a pad on the chip. To select the output circuit, either one of the two pads can be connected (using wire bonding) to a pin on the SO8 enclosure during final assembly. This saves one pin on the SO8 enclosure.

In an illustrative embodiment, the ASIC 98 is housed in an SO8 enclosure. The SO8 enclosure is suitable for surface mounting (SMD) in order to minimise the space taken up on the printed circuit board 26. In light of the number of connections for the actuator circuit, it is possible to use such an enclosure with eight connections. It is also possible to route both output circuits to the outside. Since no 9-pin enclosure exists, it would tiien be necessary to use the next feasible enclosure instead, which means having to use a 14-pin enclosure that is substantially larger than the 8-pin enclosure. It is possible, of course, to use other enclosures suitable for surface mounting (SMD versions). hi a further embodiment, the actuator circuit 98 is designed in the form of an integrated circuit which is suitable for flip-chip mounting on the printed circuit board 26 (bare chip which is mounted upside-down on the printed circuit board 26). The pads for connecting such a flip-chip element are preferably provided with raised solder locations or solder bumps, as a result of which the chip will make contact with corresponding pads on • the printed circuit board 26 as a result of heat action. This embodiment takes up even less space on the printed circuit board 26. hi the flip-chip alternative, both pads are available, and it is possible to delay making a choice with regard to the output circuit to be used until production of the hybrid, Le. at a later stage.

Claims

1. Earth leakage circuit breaker (90) for use in a safety switch, comprising:

- a detection device (91) for detecting an earth leakage current in the electric circuit of the safety switch;

- an actuator element (93) for breaking the electric circuit of the safely switch;

- an actuator circuit (98), connected to the detection device (91) and the actuator element (93), for energising title actuator element (93) in the event of an earth leakage current in excess of a predefined threshold being detected, where the actuator circuit (98) is provided with a selection connection (97) for selecting the type of actuator element (93) that has to be actuated.

2. Earth leakage circuit breaker according to Claim 1, wherein the type of actuator element (93) is a solenoid type and wherein the actuator circuit (98) enables the actuator element (93) by means of a thyristor stage.

3. Earth leakage circuit breaker according to Claim 1, wherein the type of actuator element (93) is a latch type and wherein the actuator circuit (98) enables the actuator element (93) by means of an open collection stage.

4. Earth leakage circuit breaker according to Claim 1 , wherein the type of actuator element (93) is a piezo element and wherein the actuator circuit (98) enables the actuator element (93) by means of a high-voltage output stage.

5. Earth leakage circuit breaker according to one of Claims 1 - 4, wherein the actuator circuit (98) is comprised in an integrated circuit.

6. Earth leakage circuit breaker according to Claim 5, wherein the actuator circuit (98) is comprised in an ASIC.

7. Earth leakage circuit breaker according to Claim 5, wherein the actuator circuit (98) is comprised in an enclosure for surface mounting.

8. Earth leakage circuit breaker according to one of Claims 1 - 4, wherein the actuator circuit (98) in manufactured in the form of an integrated circuit which is suitable for flip- chip assembly.

9. Earth leakage circuit breaker according to one of the preceding claims, further comprising a supply circuit (92) for supplying power to the actuator circuit (98), wherein the supply circuit is detachably connected to a phase terminal (1) and a neutral terminal (17) of the safety switch.

10. Earth leakage circuit breaker according to one of the preceding claims, further comprising a supply circuit (92) for supplying power to the actuator circuit (98), wherein the supply circuit (92) has a capacitive input impedance.

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