DE20308446U1 - Switching apparatus with voltage free outputs e.g. for rail vehicles, has base with relay and electronic module, which supplies relay with constant current independently of supply voltage - Google Patents

Abstract

The switching apparatus consists of a base (1), a relay, and an electronic module and can only be used as a unit with these components. The connections for the supply voltage and the switch output are logically separated. The base receives the relay and the electronic module, which supplies the relay with a constant current independent of the supply voltage.

Description

Annex 1 / Description

SHC / h.t / 26 May 2003

Switching device with potential-free outputs according to DIN EN 501 55

Description The switching device allows potential-free switching of:

1. electronic signals or

2. electrical currents for operating downstream devices

via relay contacts and is independent of fluctuations in the supply voltage according to DIN EN 50155 "Electronic equipment on railway vehicles".

The switching device consists of three main

Assemblies,

-Base, Fig. 1 + 2 (1)

- Relay, Fig. 1 + 3 (2)

- Electronics module, Fig. 1 + 4 (3)

which can only be used as a unit (Fig. 5).

- the base (1) is used to hold the relay (2) and the electronic module (3). As an option, the relay (2) can be attached to the base (1) with a metal or plastic bracket. The base (1) can be snapped onto a 35mm DIN rail or attached to a mounting plate using two screws. The base (1) is logically separated; in accordance with VDE 0106, the connections for the supply voltage and the switching outputs are spatially separated. The connection terminals in the base (1) can be designed either as screw terminals or spring-loaded terminals.

- A plug-in or print relay with changeover or normally open / normally closed contacts can be used as relay (2). The configuration of the potential-free contacts is essentially determined by the application.

- the electronic module (3) supplies the relay coil (2) with a constant current Il, independent of the supply voltage Un-

Annex 1 / Page 2

The supply voltage Un (Fig. 6) can be between 0.7 and 1.25 of the nominal value in accordance with DIN EN 501 55. The electronics are designed so that the maximum coil current Item can flow for approx. 20ms after the supply voltage Un is applied, so that the relay coil (Fig. 6) switches on reliably. After 20ms, the coil current I _L is then limited to a constant value, independent of the supply voltage.

Appendix la

SHC / h.t / 26 May 2003

Switching device with potential-free outputs according to DIN EN 501 55

State of the art:

The switching devices used today are so-called auxiliary contactors, which do not meet the increased requirements for more comfort in rail vehicles for two reasons:

The problem:

Solution:

1. More and more electrical signals are required for control in rail vehicles and auxiliary contactors are relatively large, the control cabinet in rail vehicles is limited. So there are space problems.

2. A large number of control signals are processed by microcontrollers. Auxiliary contactors are robust and mechanically very stable, but they cannot properly switch small currents, such as those required by a microcontroller to detect signals.

Lack of space and small currents are the problem and could be solved with a relay if it were not for the fact that relays are dependent on the supply voltage. The smaller the applied voltage, the lower the current that flows through the excitation coil. If the current is too small, the contacts cannot close sufficiently or the so-called rest contact has a low pressure in the "currentless" state and can assume an undefined state when subjected to shock or vibration. This means that the application does not comply with DIN EN 501 55 and must be discarded.

The complexity of the problems is solved by the switching device as described in Appendix 1 and the drawings Sheets 1 + 2.

continue page 2

The benefits achieved:

Annex 1 a / Page 2

The invention ensures that the excitation coil of the relay is always supplied with a constant coil current by the electronic module (current source with pulse width modulation). This is the only way to ensure that the potential-free contacts are always set at the factory to the maximum contact pressure of the springs. The advantages in summary:

Further design

1. The excitation coil of the relay is always supplied with sufficient and constant current via the electronic module, which is necessary for operation

2. Because the coil receives enough current, the potential-free contacts do not need to be set to the lowest current (relay without electronic module at the lowest possible supply voltage) and have the max. contact pressure, even at the smallest control currents.

3. The higher the contact pressure, the less sensitive the control unit is to vibration, shock or oscillation stress according to DIN EN 50155.

The invention is not limited to one type of relay, but can be used in the combination shown with an electronic module for all relays.

Claims (1)

Switching device with potential-free outputs according to DIN EN 50155 ( Fig. 1) consisting of a base ( 1 ), a relay ( 2 ) and an electronic module ( 3 ), characterized in that the electrical functionality according to DIN EN 50155 is only maintained in the combination of the individual components ( 1 ), ( 2 ) and ( 3 ), ( Fig. 1).
Purpose of the device Switching device which generates a constant coil current with fluctuating supply voltage.