Lock-Out, Tag-Out System Using Safety Network

A power control circuit for a power control cabinet comprising an arc-flash resistant housing and holding:

• a first and second contactor each providing a coil switching independent contacts, the contacts of the first contactor in series with contacts of the second contactor, each series-connected contact receiving at a first terminal electrical power from the second releasable electrical connector from a power source and providing switched power from a second terminal to the second releasable electrical connector for operation of a motor;
• a voltage sensor detecting voltage at the second terminal;
• a safety network interface element providing control signals to the coils of the first and second contactors and communicating with the voltage sensor to receive input signals from the voltage sensor, the safety network interface element providing redundant communication on a serial network with remote lock-out switches to provide an SIL-3 reliable communication to receive data of the control signals and to transmit data of the input signals on the serial network
• wherein the safety network interface element and the remote lock-out, switches communicate peer-to-peer without an intervening safety controller.

A lock-out, tag-out station comprising:

• (a) contacts having a shared operator, the operator adapted to receive a padlock when the operator is in a deactivation position, the padlock blocking actuation of the operator,
• (b) a display indicating deactivation of at least one associated motor circuit;
• and
• (c) a first safety network interface element connected to the contacts and the display to transmit a contact state and receive a display state using redundant data on a serial network configured to provide SIL-3 reliable communication to system isolation equipment on a peer-to-peer basis with a second safety network interface element without an intervening programmable logic controller.

A lock-out, tag-out system for a motor control center of the type providing for multiple bucket-receiving openings and holding conductors for communicating with motor circuitry, the lock-out, tag-out system providing a bucket comprising

• an arc-flash resistant housing fitting within the motor control center and holding:
• a first contactor providing a coil switching contacts receiving at first terminals electrical power from a power source and providing switched power at second terminals;
• a voltage sensor detecting voltage at the second terminals;
• a safe-off motor drive having power terminals connected to the second terminals, the power terminals providing internal power for the safe-off motor drive, the safe-off motor drive further including a switch element disconnecting internal power from power semiconductors used to synthesize motor drive voltages;
• a safety network interface element:
• (a) providing a control signal to the coil of the first contactor;
• (b) communicating with the voltage sensor to receive input signals from the voltage sensor;
• (c) providing a control signal to the switch element;
• the safety network interface element providing redundant communication on a serial network with remote lock-out switches to provide an SIL-3 reliable communication to receive data of the control signals and to transmit data of the input signals on the serial network
• wherein the safety network interface element and the remote lock-out, switches communicate peer-to-peer without an intervening safety controller.

A lock-out, tag-out system for a power control cabinet, the lock-out, tag-out system comprising:

• (1) at least one lock-out, tag-out station providing:
• (a) at least two contacts having a shared operator for receiving a padlock when the operator is in a deactivation position, the padlock blocking actuation of the operator,
• (b) a display indicating deactivation of at least one associated motor circuit;
• and
• (c) a first safety network interface element connected to the contacts and the display to transmit a contact state and receive a display state using redundant data on a serial network configured to provide SIL-3 reliable communication;
• (2) power control circuit positionable in the power control cabinet, the power control circuit providing:
• (a) at least one of a pneumatic valve or hydraulic valve system used to remove hydraulic and pneumatic power from a machine;
• (b) a second safety network interface element communicating on the serial network to receive the contact state to control the at least one of a pneumatic valve or hydraulic valve system and transmit display state derived from the pressure sensor detecting removal of pneumatic or hydraulic energy from the at least one of a pneumatic valve or hydraulic valve system;
• wherein the first and second safety network interface communicate peer-to-peer without an intervening safety controller.