Integrity testing of isolation means in an uninterruptible power supply

• US 20060108875A1
• Filed: 11/15/2005
• Published: 05/25/2006
• Est. Priority Date: 11/22/2004
• Status: Active Grant

• Current Assignee: Inventio AG (Schindler Holding AG)
• Original Assignee: Inventio AG (Schindler Holding AG)
• Inventors: Grundmann, Steffen, Gremaud, Nicolas
• Granted Patent: US 7,453,169 B2
• Time in Patent Office: Days
• US Class Current: 307/70
• CPC Class Codes: G01R 31/1227 of components, parts or materials G01R31/1209, G01R31/1218, G01R31/18 take precedence; circuits therefor G01R31/14; testing vessels of electrodes G01R31/16
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

An uninterruptible power supply wherein an isolation device is automatically tested during normal operation to ensure that it is capable of effectively isolating the input from an auxiliary power supply during emergency operation. The uninterruptible power supply includes an input for coupling to a main power supply, an output for connection to an electrical load, an auxiliary power supply and a selective isolation device configured to isolate the auxiliary power supply from the input during emergency operation. First components establish a reverse polarity across the isolation device for a test period during normal operation, and second components monitor a voltage proportional to the input voltage to the isolation device and output an error signal if the monitored voltage remains or rises above a first reference value during the test period.

Claims

1. An uninterruptible power supply comprising:

a supply input adapted to be connected to a main power supply;

an output adapted to be connected to an electrical load;

an auxiliary power supply;

a selective isolation means connected between said supply input and said auxiliary power supply for isolating said auxiliary power supply from said supply input during an emergency operation;

a first means establishing a reverse polarity across said isolation means for a test period during normal operation; and

a second means monitoring a voltage proportional to an input voltage to said isolation means and outputting an error signal if the monitored voltage remains at or rises above a first reference value during the test period.

2. The uninterruptible power supply according to claim 1 wherein said auxiliary power supply is at least one rechargeable energy storage unit.

3. The uninterruptible power supply according to claim 1 wherein said first means includes a resistor and a transistor connected in series between an input to said isolation means and an electrical ground.

4. The uninterruptible power supply according to claim 1 including a choke connected between said supply input and an input to said isolation means.

5. The uninterruptible power supply according to claim 1 including a resistor connected between an input to said isolation means and an electrical ground, and wherein said first means includes a disconnection switch connected between a main power supply and said isolation means.

6. The uninterruptible power supply according to claim 1 including a transformer having a primary winding connected between an output of said isolation means and an input of said auxiliary power supply, and wherein said first means includes a secondary winding of said transformer, a resistor and a transistor connected in series between said input of said auxiliary power supply and an electrical ground.

7. The uninterruptible power supply according to claim 1 wherein said second means includes a comparator for comparing the input voltage to said isolation means with the first reference value and a controller monitoring an output signal from said comparator.

8. The uninterruptible power supply according to claim 1 wherein said second means includes a first resistor network connected between an input to said isolation means and an electrical ground to generate a first voltage proportional to the input voltage, a second resistor network connected between an output of said isolation means and the electrical ground to provide the first reference value which is proportional to a voltage at an output of said isolation means, and a controller comparing the first voltage with the first reference value.

9. The uninterruptible power supply according to claim 1 including a comparator comparing a voltage at an output of said uninterruptible power supply with a second reference value and outputting a test commence signal if the output voltage is greater than the second reference value.

10. A method for testing a selective isolation means used in an uninterruptible power supply to isolate an auxiliary power supply from an input during emergency operation, comprising the steps of:

establishing a reverse polarity across the isolation means for a test period during normal operation of the uninterruptible power supply;

monitoring a voltage proportional to an input voltage to the isolation means; and

outputting an error signal if the monitored voltage remains at or rises above a first reference value during the test period.

11. The method according to claim 10 including comparing a voltage at an output of the uninterruptible power supply with a second reference value and outputting a test commence signal if the output voltage is greater than the second reference value.