Fault detection in relay drive circuits

• US 5,210,756 A
• Filed: 09/26/1990
• Issued: 05/11/1993
• Est. Priority Date: 09/26/1990
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Kummer, Karl T., Duong, Hieu T., McLaughlin, Paul F., Bristow, Robert W.
• Primary Examiner(s): Beausoliel, Jr., Robert W.
• Assistant Examiner(s): CHUNG, PHUNG M
• Application Number:
  US07/588,387
• Time in Patent Office: 958 Days
• Field of Search: 371/8.1, 371/8.2, 371/9.1, 371/36, 371/68.1, 371/68.2, 371/68.3, 371/25.1, 371/20.1, 370/112
• US Class Current: 714/4.2
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• CPC Class Codes: G06F 11/2221 to test input/output devices or peripheral units

Abstract

A system has at least one output device, the output device having a first set of output terminals connected to a corresponding field device. Each output device has a corresponding redundant output device having a corresponding first set of output terminals connected to the same corresponding field device as the corresponding output device. The output device and the redundant output device each have a second set of output terminals corresponding to the first set of output terminals, the second set of output terminals being connected to an apparatus for controlling the information outputted from the first set of output terminals. The apparatus comprises a plurality of switching elements, having a set of first and second contact points. Each of the second set of output terminals of the output device being connected to a corresponding first contact point, and the second set of output terminals of the redundant output device being connected to the corresponding second contact point. An activating element activates the plurality of switching elements in response to a control signal from the output device and the redundant output device such that the information outputted from the output device or the redundant output device is prevented from being coupled to the field device.

Claims

1. In a system having at least one output device (21A), the output device having n output terminals, where n=1 to N, for outputting information, and wherein each output device has a corresponding redundant output device (21B), the corresponding redundant output device having corresponding n'"'"' output terminals, where n'"'"'=1'"'"' to N'"'"' for outputting information, the n and n'"'"' output terminals each being operatively connected to a corresponding m field device (250), where m=1 to N, through an apparatus, such that only the information outputted from one of the corresponding n and n'"'"' output terminals is coupled to the corresponding field device m, said apparatus comprising:

a) at least one fist current source means (211A) for outputting a current, each first current source means being connected to the corresponding output terminal (n) of the output device (21A), the current outputted from each first current source means containing the information outputted from each corresponding output terminal (n) of the output device (21A);

b) at least one second current source means (211B) for outputting a current, each second current source means being connected to the corresponding output terminal (n'"'"') of the corresponding redundant output device (21B), the current outputted from each second current source means containing the information outputted from each corresponding output terminal (n'"'"') of the redundant output device (21B);

c) at least one first diode (212A), each first diode connected to the corresponding first current source means (211A) and to corresponding first connector terminals (11A), and further wherein each connection between the first diode and the corresponding first current source means are each connected to corresponding second connector terminals (12A);

d) at least one second diode (212B), each second diode connected to the corresponding second current source means (211B) and to corresponding first redundant connector terminals (11B), and further wherein each connection between the second diode and the corresponding second current source means are each connected to corresponding second redundant connector terminals (12B), and further wherein each first redundant connector terminal (11B) is connected to the corresponding first connector terminal (11A), and further connected to the corresponding field device (250-1, 250-2, . . . , 250-8), thereby providing a path for coupling information from the output terminals (n) of the output device and the output terminals (n'"'"') of the redundant output device to the corresponding field devices;

e) at least one switching means (253) for switching, the number of switching means being from 1 to n, each switching means having corresponding n first contact points (256) and n second contact points (257), each second connector terminals (12A, 22A, . . . 82A), being connected to corresponding first contact points (256-1, 256-2, . . . , 256-8), and each second redundant connector terminals (12B, 22B, . . . 82B) being connected to corresponding second contact points (257-1, 257-2, . . . 257-8); and

f) activating means (254), operatively connected to the output device (21A) and the redundant output device (21B), for activating each switching means in response to control signals, control signal A and control signal B, CONTA and CONTB, respectively, from the output device and the redundant output device, such that the information outputted from the output terminals of the output device or the information outputted from the output terminals of the redundant output device is caused to be bypassed by the switching means resulting in the unbypassed information being coupled to the corresponding field device.

2. An apparatus, according to claim 1, wherein said apparatus further comprises:

a) driver means, interposed between said activating means and said output device (21A) and said redundant output device (21B), for driving control signals to said activating means; and

b) receiver means, interposed between said activating means and said output device (21A) and said redundant output device (21B), to output the control signals received by said driver means.

3. An apparatus, according to claim 2, wherein said apparatus further comprises:

voting circuit means, operatively connected to said receiver means, for voting, to output a result signal indicating all the inputs have changed state, the result signal being coupled to the output device and the redundant output device.

4. An apparatus according to claim 3, wherein said switching means comprises:

a) a plurality of single-pole double-throw relay contact sets.

5. An apparatus according to claim 4, wherein said activating means comprises:

a) at least one relay coil, each relay coil controlling the operation of a plurality of relay contact sets.

6. In a system having at least one output device, the output device having a first set of output terminals for outputting information, wherein each of said first set of output terminals is operatively connected to a corresponding field device, and wherein each output device has a corresponding redundant output device, the redundant output device having a corresponding first set of output terminals for outputting information, each of said first set of output terminals of the redundant output device being operatively connected to the corresponding first set of output terminals of the corresponding output device, the output device and the redundant output device each having a second set of output terminals corresponding to the first set of output terminals, the second set of output terminals of the output device and the redundant output device being connected to an apparatus for controlling the information outputted from the first set of output terminals such that only the information outputted from the output device or the information outputted from the redundant output device is coupled to the corresponding field device, the apparatus including a plurality of switching elements each having a first contact point and second contact point, and an activating element for activating the switching element, a method for verifying the operability of said apparatus comprising the steps of:

a) transmitting a first control signal from said redundant output device thereby preventing said activating element to cause the switching element to switch;

b) transmitting a second control signal from said output device to cause the second control signal to stimulate the activating element nowithstanding the stimulation by the first control signal; and

c) observing at least one resultant signal returned from the activating element to the redundant output device to compare to an expectant result thereby verifying the operability of the activating element.