Safety switching device for setting a safety-related device to a safe state

• US 20120299578A1
• Filed: 07/23/2012
• Published: 11/29/2012
• Est. Priority Date: 08/02/2005
• Status: Active Grant

• Current Assignee: Phoenix Contact GmbH & Company KG
• Original Assignee: Phoenix Contact GmbH & Company KG
• Inventors: Korrek, Andre
• Granted Patent: US 9,239,572 B2
• Time in Patent Office: Days
• US Class Current: 324/76.15
• CPC Class Codes: G05B 9/02 electric
• CPC Class Codes: H01H 47/002 Monitoring or fail-safe circuits
• CPC Class Codes: H01H 51/005 Inversing contactors H01H50/323 takes precedence
• CPC Class Codes: H01H 9/542 Contacts shunted by static switch means
• CPC Class Codes: H02P 23/24 Controlling the direction, e.g. clockwise or counterclockwise
• CPC Class Codes: H03M 1/12 Analogue/digital converters H03M1/001 – H03M1/10 take precedence
• CPC Class Codes: H03M 1/207 using a digital interpolation circuit

Abstract

A safety switching device, with which a safety-related device, can be set into a safe state. The safety switching device has a microprocessor or microcontroller, which can set an electric drive to be protected into a safe state both if an emergency circuit breaker, protective door switch, and/or two-hand switch is activated and also if there is faulty operation of the safety-related device or electric drive. For this purpose, the microprocessor is implemented such that it can determine from at least one analog signal to be measured whether a predetermined parameter lies outside a predetermined operating range. In addition, the microprocessor can be a component of a safety device which is constructed for multiple-channel control of a safety-related electric drive. In this way, the safety switching device can respond to several safety functions independent of each other in order to set an electric drive into a safe state.

Claims

1. A measurement device (10) for measuring a periodic analog signal, whose amplitude can lie outside a predetermined operating range, comprising:

a determining device (20, 30, 40, 50) for determining the time period during which the amplitude of the of the analog signal to be measured lies outside the predetermined operating range, and

an evaluation device (60), which calculates the maximum amplitude of the analog signal to be measured from the determined time period and the signal shape of the analog signal to be measured.

2. The measurement device (610) according to claim 1, characterized in that the determining device has a sampling device (620) for sampling the analog signal to be measured at a sampling rate and a device (640, 650) for detecting and counting successive sampled values which are greater than or equal to a predetermined threshold in terms of magnitude, and in that the evaluation device (660) is constructed for calculating the maximum amplitude of the analog signal as a function of the number of counted sampled values, the sampling rate, and the signal frequency of the analog signal to be measured.

3. The measurement device according to claim 1, characterized in that the analog signal is a sinusoidal signal with a predetermined signal frequency and that the evaluation device (660) calculates the maximum amplitude value using the equation

8. A device protected against overcurrents, comprising:

a measurement device (610) according to claim 1; and

a disconnect device, which deactivates the protected device as a response to the calculated maximum amplitude value.

4. A measurement device for measuring a periodic analog signal, which can lie outside a predetermined operating range, the device comprising:

a sampling device (620) for sampling the analog signal at a sampling rate;

a device (640, 650) for detecting and counting successive sampled values that are greater than or equal to a predetermined threshold in terms of magnitude;

a memory device (670) that stores the maximum amplitude value lying outside the predetermined operating range for several reference signals and the associated number of counted sampled values that are greater than or equal to a predetermined threshold in terms of magnitude; and

an evaluation device (660), which reads the associated maximum amplitude value from the memory device as a response to the number of sampled values determined by the detecting and counting device (640, 650).

5. The measurement device according to claim 4, characterized by an AD converter (630) for converting the sampled values into corresponding digital values.

6. The measurement device according to claim 4, characterized in that the sampling rate is adjustable.

7. The measurement device according to claim 4, characterized in that the threshold coincides with or is lower than the limiting value of the predetermined operating range.

9. A method for measuring a periodic analog signal, whose amplitude can lie outside a predetermined operating range, the method comprising:

determining the time period during which the amplitude of the analog signal to be measured lies outside the predetermined operating range; and

calculating the maximum amplitude of the analog signal to be measured as a function of the determined time period and the signal shape of the analog signal to be measured.

10. The method according to claim 9, characterized in that determining the time period comprises:

sampling the analog signal to be measured at a sampling rate;

counting successive sampled values that are greater than or equal to a predetermined threshold in terms of magnitude; and

calculating the maximum amplitude of the analog signal as a function of the number of counted sampled values, the sampling rate, and the signal frequency of the analog signal to be measured.

11. A method for measuring a periodic analog signal, which can lie outside a predetermined operating range of a measurement device that is used, the method comprising:

determining and storing, for several reference signals, the maximum amplitude lying outside the predetermined operating range and the associated number of sampled values that are greater than or equal to a threshold in terms of magnitude;

sampling an analog signal to be measured at a sampling rate;

counting the successive sampled values that are greater than or equal to the predetermined threshold in terms of magnitude; and

reading out the maximum amplitude value belonging to the number of counted sampled values.

12. The method according to claim 11, characterized in that the sampled values are converted into digital values and successive digital values that are greater than or equal to a predetermined digital threshold are counted.