Safety power disconnection for power distribution over power conductors to power consuming devices
Safety power disconnection for remote power distribution in power distribution systems is disclosed. The power distribution system includes one or more power distribution circuits each configured to remotely distribute power from a power source over current carrying power conductors to remote units to provide power for remote unit operations. A remote unit is configured to decouple power from the power conductors thereby disconnecting the load of the remote unit from the power distribution system. A current measurement circuit in the power distribution system measures current flowing on the power conductors and provides a current measurement to the controller circuit. The controller circuit is configured to disconnect the power source from the power conductors for safety reasons in response to detecting a current from the power source in excess of a threshold current level indicating a load.
1. A power distribution system comprising:
a power distribution circuit comprising:
a distribution power input configured to receive current distributed by a power source;
a distribution power output configured to distribute the received current over a power conductor coupled to an assigned remote unit among a plurality of remote units;
a distribution switch circuit coupled between the distribution power input and the distribution power output, the distribution switch circuit comprising a distribution switch control input configured to receive a distribution power connection control signal indicating a distribution power connection mode;
the distribution switch circuit configured to be closed to couple the distribution power input to the distribution power output in response to the distribution power connection mode indicating a distribution power connect state; and
the distribution switch circuit further configured to be opened to decouple the distribution power input from the distribution power output in response to the distribution power connection mode indicating a distribution power disconnect state; and
a current measurement circuit coupled to the distribution power output and comprising a current measurement output;
the current measurement circuit configured to measure a current at the distribution power output and generate a current measurement on the current measurement output based on the measured current at the distribution power output; and
a controller circuit comprising:
a current measurement input communicatively coupled to a current measurement output of the current measurement circuit of the power distribution circuit; and
the controller circuit configured to:
generate the distribution power connection control signal indicating the distribution power connection mode to the distribution switch control input of the power distribution circuit indicating the distribution power connect state;
determine if the measured current on a current measurement input among the one or more current measurement inputs of the power distribution circuit exceeds a predefined threshold current level when the distribution switch circuit is closed to couple the distribution power input to the distribution power output;
in response to the measured current of the power distribution circuit exceeding the predefined threshold current level, communicate the distribution power connection control signal indicating the distribution power connection mode to the distribution switch control input of the power distribution circuit indicating the distribution power disconnect state; and
communicate a remote power connection signal comprising a change in voltage levels indicating a remote power disconnect state to cause the assigned remote unit to decouple current from the power conductor of the power distribution circuit.
2. The power distribution system of claim 1 , in response to the measured current of the power distribution circuit not exceeding the predefined threshold current level, communicate the distribution power connection control signal comprising the distribution power connection mode to the distribution switch control input of the power distribution circuit indicating the distribution power connect state.
3. The power distribution system of claim 1 , wherein the controller circuit is further configured to communicate the remote power connection signal comprising a remote power connection mode indicating the remote power disconnect state before determining if the measured current on the current measurement input exceeds the predefined threshold current level.
4. The power distribution system of claim 1 , wherein the controller circuit is further configured to communicate the remote power connection signal comprising a remote power connection mode indicating a remote power connect state over a distribution management communications output coupled to the assigned remote unit to the power distribution circuit to cause the assigned remote unit to couple to the power conductor of the power distribution circuit.
5. The power distribution system of claim 4 , wherein the controller circuit is configured to communicate the remote power connection signal comprising the remote power connection mode indicating the remote power connect state after a predefined time has elapsed after communicating the remote power connection signal comprising the remote power connection mode indicating the remote power disconnect state.
6. The power distribution system of claim 5 , wherein the remote power connection signal indicating the remote power connect state comprises a change in voltage level that increases the voltage level.
7. The power distribution system of claim 1 , wherein the predefined threshold current level is less than 200 milliAmps (mA).
8. The power distribution system of claim 1 , wherein the predefined threshold current level is less than 100 milliAmps (mA).
9. The power distribution system of claim 1 , wherein the controller circuit is further configured to periodically generate a watchdog signal; and
further comprising a watchdog controller configured to:
receive the watchdog signal; and
in response to not receiving the watchdog signal within a predefined time period, cause the distribution power connection control signal to indicate the distribution power disconnect state.
10. A power distribution system comprising:
a power distribution circuit comprising:
a distribution power input configured to receive current distributed by a power source;
a distribution power output configured to distribute the received current over a power conductor coupled to an assigned remote unit among a plurality of remote units;
a distribution switch circuit coupled between the distribution power input and the distribution power output, the distribution switch circuit comprising a distribution switch control input configured to receive a distribution power connection control signal indicating a distribution power connection mode;
the distribution switch circuit configured to be closed to couple the distribution power input to the distribution power output in response to the distribution power connection mode indicating a distribution power connect state; and
the distribution switch circuit further configured to be opened to decouple the distribution power input from the distribution power output in response to the distribution power connection mode indicating a distribution power disconnect state; and
a current measurement circuit coupled to the distribution power output and comprising a current measurement output;
the current measurement circuit configured to measure a current at the distribution power output and generate a current measurement on the current measurement output based on the measured current at the distribution power output; and
a controller circuit comprising:
a current measurement input communicatively coupled to a current measurement output of the power distribution circuit; and
the controller circuit configured to:
generate the distribution power connection control signal indicating the distribution power connection mode to the distribution switch control input of the power distribution circuit indicating the distribution power connect state;
determine if the measured current on a current measurement input among the one or more current measurement inputs of the power distribution circuit exceeds a predefined threshold current level when the distribution switch circuit is closed to couple the distribution power input to the distribution power output;
in response to the measured current of the power distribution circuit exceeding the predefined threshold current level, communicate the distribution power connection control signal indicating the distribution power connection mode to the distribution switch control input of the power distribution circuit indicating the distribution power disconnect state;
lower a voltage level on the distribution power output from a first voltage level to a second voltage level distributing the received current over the power conductor coupled to the assigned remote unit; and
raise the voltage level on the distribution power output from the second voltage level to the first voltage level distributing the received current over the power conductor coupled to the assigned remote unit.