Relay unit, control method for relay unit

Patent metadata

Field	Value
Publication number	US-9997316-B2
Application number	US-201514881858-A
Country	US
Kind code	B2
Filing date	Oct 13, 2015
Priority date	Feb 2, 2015
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

The reliability of testing a normally closed contact in a relay unit may involve the following. While the load is de-energized, sending a test signal to a normally closed contact (b 1 , b 2 ) and detecting the state of the returning test signal sent. Resending a test signal when a detection result does not satisfy a predetermined criteria, and re-detecting the state of the returning test signal resent. The state of the returning test signal resent may be assessed as normal when the re-detection result satisfies the predetermined criteria.

First claim

The invention claimed is:

1. A relay unit comprising:
a switching circuit comprising at least one normally open contact and at least one normally closed contact; and
a controller electrically coupled to the switching circuit via a first terminal and a second terminal and configured with a program for controlling the switching circuit; wherein
the switching circuit is in a state of de-energizing a load when the normally open contact is open and the normally closed contact is closed, and the switching circuit is in a state of energizing the load when the normally open contact is closed and the normally closed contact is open;
while the load is de-energized, the controller sends a test signal to the normally closed contact via the first terminal and detects a return state of the test signal via the second terminal;
when the return state does not satisfy a predetermined criteria, the controller resends the test signal to the normally closed contact via the first terminal and re-detects a second return state of the test signal via the second terminal; and
the controller assess the second return state of the test signal as normal when the second return state of the test signal satisfies the predetermined criteria.

2. The relay unit according to claim 1 , wherein the controller assesses the second return state of the test signal as abnormal when the second return state of the test signal does not satisfy the predetermined criteria.

3. The relay unit according to claim 1 , wherein the test signal is a pulse signal, and the predetermined criteria is satisfied when a period of the returning test signal is between a lower limit threshold and an upper limit threshold, inclusive.

4. The relay unit according to claim 1 , wherein the test signal is a pulse signal, and the predetermined criteria is satisfied when a number of pulses of the returning test signal within a fixed interval is between a lower limit threshold and an upper limit threshold, inclusive.

5. The relay unit according to claim 1 , wherein the test signal is a pulse signal, and the predetermined criteria is satisfied when a period of the returning test signal is between a lower limit threshold and an upper limit threshold, inclusive, and a number of pulses of the returning test signal within the fixed interval is between a second lower limit threshold and second upper limit threshold, inclusive.

6. The relay unit according to claim 1 , wherein when the controller assesses the state of the returning test signal as normal, the controller closes the normally open contact and opens the normally closed contact to energize the load.

7. The relay unit according to claim 1 , wherein when the return state does not satisfy the predetermined criteria, the controller carries out re-detection after performing a switching operation that opens the normally closed contact momentarily and then closes the normally closed contact.

8. The relay unit according to claim 7 , wherein the controller carries out re-detection after repeating the switching operation a predetermined number of times.

9. The relay unit according to claim 7 , wherein the controller carries out re-detection after repeating the switching operation a predetermined number of times, and assesses the second return state as normal and halts the switching operation at the point the second return state satisfies the predetermined criteria.

10. The relay unit according to claim 1 , wherein in a condition in which the return state does not satisfy a predetermined criteria the controller carries out re-detection after a predetermined amount of time has passed.

11. The relay unit according to claim 1 , wherein the switching unit comprises a plurality of the normally closed contacts, and the controller carries out the detection and the re-detection of the signals returning from the plurality of normally closed contacts individually.

12. The relay unit according to claim 1 , wherein the switching unit comprises a plurality of the normally closed contacts connected in series, and the controller carries out the detection and the re-detection with an identical test signal sent to the plurality of normally closed contacts connected in series.

13. The relay unit according to claim 12 , wherein when the return state does not satisfy the predetermined criteria, the controller carries out the re-detection after opening one normally closed contact momentarily and then closing the normally closed contact, and subsequently opening another normally closed contact momentarily and then closing the other normally closed contact.

14. The relay unit according to claim 1 , wherein the switching unit comprises a plurality of the normally closed contacts, and the controller carries out the re-detection from one normally closed contact on the basis of the return state from the one normally closed contact and another normally closed contact.

15. The relay unit according to claim 2 , wherein when the controller assesses that the return state of the test signal is abnormal, the controller opens the normally open contact and closes the normally closed contact to maintain the load in a de-energized state.

16. The relay unit according to claim 2 , wherein the controller comprises a notification unit for providing an external notification when the controller assesses that the return state of the test signal is abnormal.

17. A control method for a relay unit equipped with a switching circuit, the switching circuit comprising:
at least one normally open contact and at least one normally closed contact; and
a controller electrically coupled to the switching circuit via a first terminal and a second terminal and configured with a program for controlling the switching circuit; wherein
the switching circuit is in a state of de-energizing a load when the normally open contact is open and the normally closed contact is closed, and the switching circuit is in a state of energizing the load when the normally open contact is closed and the normally closed contact is open;
the control method comprising:
sending, while the load is de-energized, a test signal to the normally closed contact;
detecting a return state of the test signal;
resending, when the return state does not satisfy a predetermined criteria, the test signal;
re-detecting a second return state of the test signal; and
assessing the second return state of the test signal as normal when the second return state satisfies the predetermined criteria.

18. The control method according to claim 17 , further comprising assessing the second return state of the test signal as abnormal in when the second return state does not satisfy the predetermined criteria.

19. The control method according to claim 17 , wherein the test signal is a pulse signal, and the predetermined criteria is satisfied when a period of the test signal is between a lower limit threshold and an upper limit threshold, inclusive.

20. The control method according to claim 17 , wherein the test signal is a pulse signal, and the predetermined criteria is satisfied when a number of pulses within a fixed interval of the test signal is between a lower limit threshold and an upper limit threshold, inclusive.

Assignees

• Omron Tateisi Electronics Co

Inventors

• Fukumoto Tetsuya
• Higuchi Toshiyuki
• Murakami Kohei
• Yayama Keishi
• Fujii Satoshi

Classifications

• H01H2300/052

  Controlling, signalling or testing correct functioning of a switch · CPC title

• H01H47/002 Primary

  Monitoring or fail-safe circuits · CPC title

• H01H47/22

  for supplying energising current for relay coil · CPC title

• H01H2047/003

  Detecting welded contacts and applying weld break pulses to coil · CPC title