US 12,235,320 B2
Safety switching apparatus, in particular for the monitored switching on of an electrical and/or electronic load
Henry Peter, Einbeck (DE); and Felix Franke, Bad Pyrmont (DE)
Assigned to Phoenix Contact GmbH & Co. KG, Blomberg (DE)
Filed by Phoenix Contact GmbH & Co. KG, Blomberg (DE)
Filed on May 2, 2023, as Appl. No. 18/142,439.
Claims priority of application No. 102022110812.0 (DE), filed on May 3, 2022.
Prior Publication US 2023/0358807 A1, Nov. 9, 2023
Int. Cl. G01R 31/327 (2006.01); G01R 15/22 (2006.01); G01R 19/00 (2006.01); H02H 3/02 (2006.01)
CPC G01R 31/327 (2013.01) [G01R 15/22 (2013.01); G01R 19/0092 (2013.01); H02H 3/02 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A safety switching apparatus for the monitored switching on of an electrical and/or electronic load, comprising:
a first input and a second input, to each of which an activation signal can be applied;
a third input, which is designed to apply a supply voltage for supplying power to the electrical load;
a test voltage supply device;
an output, which is designed to connect the electrical load, wherein a load current path extends between the third input and the output;
first and second changeover switches each having an excitation coil, a normally closed contact, a normally open contact, and a common center terminal, wherein the first changeover switch and the second changeover switch are electrically connected to each other by means of the respective common center terminals, wherein the normally open contacts of the first and second changeover switches are arranged in series with each other in said load current path, wherein the excitation coil of the first changeover switch is arranged in a first control current path electrically connected to the first input, and the normally closed contact of the first changeover switch is arranged in a first diagnostic circuit, wherein the excitation coil of the second changeover switch is arranged in a second control current path electrically connected to the second input, and the normally closed contact of the second changeover switch is arranged in a second diagnostic circuit, wherein the first diagnostic circuit and the second diagnostic circuit are connected in parallel to the test voltage supply device;
a first diagnostic current detecting device associated with the first diagnostic circuit and adapted to provide a first control signal only when the first diagnostic circuit is closed by means of the normally closed contact of the first changeover switch;
a second diagnostic current detecting device associated with the second diagnostic circuit and adapted to provide a second control signal only when the second diagnostic circuit is closed by means of the normally closed contact of the second changeover switch;
a first controllable short-circuit device electrically connectable to the second input; and
a second controllable short-circuit device electrically connectable to the first input, wherein the first short-circuit device is adapted to short-circuit the excitation coil of the first changeover switch in response to a first activation signal applied to the second input only when the second diagnostic current detecting device provides the second control signal during a predetermined time period after the first activation signal is applied, and wherein the second short-circuit device is adapted to short-circuit the excitation coil of the second changeover switch in response to a second activation signal applied to the first input only when the first diagnostic current detection device provides the first control signal during a predetermined time period after the second activation signal is applied.