Static transfer switch

• US 9,537,348 B2
• Filed: 03/14/2013
• Issued: 01/03/2017
• Est. Priority Date: 09/14/2012
• Status: Active Grant

• Current Assignee: Vetriv S.R.L.
• Original Assignee: Chloride SRL (Emerson Electric Company)
• Inventors: Bertuzzi, Giancarlo, Cinti, Ugo, Galuppi, Graziano
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Warmflash, Michael
• Application Number:
  US13/804,424
• Publication Number:
  US 20140097689A1
• Time in Patent Office: 1,391 Days
• Field of Search: 307/64, 307/115, 307/125
• US Class Current: 1/1
• CPC Class Codes: H02J 9/04 in which the distribution system is disconnected from the normal source and connected to a standby source
• CPC Class Codes: H03K 17/18 Modifications for indicating state of switch
• CPC Class Codes: H03K 17/725 for ac voltages or currents H03K17/722, H03K17/735 take precedence
• CPC Class Codes: H03K 17/735 Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors H03K17/722 takes precedence; logic circuits H03K19/00; code converters H03M5/00, H03M7/00

Abstract

A static transfer switch is used for switching an output load from a first power source to a second power source. A first switching unit has a first pair of silicon controlled rectifiers (SCR). A second switching unit has a second pair of SCRs arranged in an anti-parallel configuration. The control circuit determines whether at least one of the SCRs is activated in accordance with the voltage between the gate and the cathode of the at least one SCR. If the voltage between the gate in the cathode is at least 150 mV, the control circuit indicates that the at least one of the SCR is activated.

Claims

1. A static transfer switch to transfer an output load from a first power source to a second power source, the static transfer switch comprising:

a first switching unit having a first silicon controlled rectifier (SCR);

a second switching unit having a second SCR; and

a control circuit configured to determine whether at least one of the first SCR or the second SCR is inactive, wherein the at least one of the first SCR or the second SCR is inactive when voltage between a gate and a cathode of the at least one SCR falls below 150 mV and a direct current between an anode and a cathode of the at least one SCR falls below a holding current, and the control circuit is further configured so that when the voltage between the gate and the cathode of the at least one SCR is greater than 150 mV or the direct current between the anode and the cathode of the at least one SCR remains above the holding current, the at least one SCR is active.

2. The static transfer switch of claim 1 wherein the first SCR communicates with a first firing circuit and the second SCR communicates with a second firing circuit.

3. The static transfer switch of claim 1 wherein the control circuit outputs a status signal in accordance with activation of the at least one of the first or the second SCR.

4. A static transfer switch to transfer an output load from a first power source to a second power source, the static transfer switch comprising:

a first switching unit having a first pair of silicon controlled rectifiers (SCRs) arranged in an anti-parallel relationship;

a second switching unit having a second pair of SCRs arranged in an anti-parallel relationship; and

a control circuit configured to determine whether at least one of the SCRs is inactive when a voltage level between a gate and a cathode of the at least one of the SCRs falls below 150 mV and a direct current between an anode and a cathode of the at least one SCR falls below a holding current, and the control circuit is further configured so that when the voltage between the gate and the cathode of the at least one SCR is greater than 150 mV or the direct current between the anode and the cathode of the at least one SCR remains above the holding current, the at least one SCR is active.

5. The static transfer switch of claim 4 further comprising a control circuit communicating with the at least one of the SCRs, the control circuit determining whether the at least one of the SCRs is active and generating an output signal in accordance with activation of the at least one of the SCRs.

6. The static transfer switch of claim 5 wherein the control circuit outputs a control signal to activate at least one of the SCRs.

7. A static transfer switch, comprising:

a first switching unit having a first silicon controlled rectifier (SCR) and a second SCR arranged in an anti-parallel relationship;

a second switching unit having a third SCR and a fourth SCR arranged in an anti-parallel relationship; and

a control circuit, the control circuit configured to maintain one of the first SCR or second SCR in an active state, wherein the control circuit activates one of the third SCR or fourth SCR, causing the one of the first SCR or second SCR to transition to a not active state via a reverse voltage, after which the other of the third SCR or fourth SCR may be active,

wherein the control circuit is configured to determine whether the one of the first SCR or second SCR and the one of the third SCR or fourth SCR is inactive when the voltage between a gate and a cathode of the respective SCR falls below at least 150 mV and a direct current between an anode and a cathode of the one of the first SCR or second SCR and the one of the third SCR or fourth SCR falls below a holding current, and the control circuit is further configured so that when the voltage between the gate and the cathode is greater than 15 mV or the direct current between the anode and the cathode of the one of the first SCR or second SCR and the one of the third SCR or fourth SCR remains above the holding current, the SCR is determined to be active.

8. The static transfer switch of claim 7 wherein the first switching unit is configured to communicate with a first firing circuit and the second switching unit communicates with a third firing circuit.

9. The static transfer switch of claim 7 wherein the first switching unit communicates with a second firing circuit and the second switching unit communicates with a fourth firing circuit, wherein the first, second, third, and fourth SCRs communicate with a respective first, second, third, and fourth firing circuit.