Methods and systems for detecting manhole events

1. A system for use with a connection extending between different first and second underground vaults, the connection comprising a wall and a terminus opening into the first underground vault, the wall defining an annulus, a cable extending through the annulus and outwardly therefrom beyond the terminus, a flow comprising one or more gases flowing through the annulus alongside the cable, the system comprising:

a flow restrictor comprising a restriction device and a through-channel, the restriction device being configured to be installed in the annulus alongside the cable and to restrict the flow through the annulus, the through-channel being configured to allow a concentrated flow of the one or more gases to flow therethrough;

a perturbation detector configured to detect a value of a property of the concentrated flow and to transmit a signal encoding information based on the value; and

a system controller configured to receive the signal, use the signal to determine whether a fire is occurring or has occurred, and alert a user when the system controller determines that the fire is occurring or has occurred.

2. The system of claim 1 , wherein the property is a concentration of at least one of the one or more gases.

3. The system of claim 2 , wherein the perturbation detector is positioned at or near the terminus and the concentration of the at least one gas is measured in-line with the concentrated flow.

4. The system of claim 2 , wherein the perturbation detector is positioned remotely with respect to the terminus and the concentration of the at least one gas is measured remotely.

5. The system of claim 1 , wherein the property is a temperature of at least one of the one or more gases.

6. The system of claim 1 , wherein the perturbation detector is configured to detect a magnitude of a current flowing through the cable and the signal encodes current information based on the magnitude.

7. The system of claim 6 , wherein the perturbation detector comprises a first sensor configured to detect the magnitude of the current flowing through the cable and a second sensor configured to detect the value of the property.

8. The system of claim 1 , wherein the property is a flow vector of the concentrated flow.

9. The system of claim 8 , wherein the flow vector comprises at least one of a direction and a flow rate.

10. The system of claim 1 for use with the concentrated flow comprising particulates, wherein the property is a concentration of the particulates.

11. The system of claim 10 , wherein the perturbation detector is positioned at or near the terminus and the concentration of the particulates is measured in-line with the concentrated flow.

12. The system of claim 10 , wherein the perturbation detector is positioned remotely with respect to the terminus and the concentration of the particulates is measured remotely.

13. The system of claim 10 , wherein the concentration of the particulates is detected by the perturbation detector using at least one of deposition or filtration.

14. A method comprising:

obtaining, by a system controller, an estimated temperature of a cable within an annulus of a connection to an underground vault, the connection having a terminus and a flow restrictor installed at or near the terminus, the flow restrictor comprising an open-ended through-channel interconnecting the annulus of the connection with the underground vault;

obtaining, by the system controller, a channel temperature inside the open-ended through-channel;

determining, by the system controller, an exothermic event is likely occurring when the channel temperature is greater than the estimated temperature by more than a threshold amount; and

alerting, by the system controller, a user when the system controller determines the exothermic event is likely occurring.

15. The method of claim 14 , further comprising:

installing the flow restrictor at or near the terminus with the open-ended through-channel interconnecting the annulus of the connection with the underground vault.

16. A method for use with an annulus of a connection interconnecting first and second underground vaults, the connection having a first terminus and a first flow restrictor installed at or near the first terminus, the first flow restrictor comprising a first open-ended through-channel interconnecting the annulus of the connection with the first underground vault, the connection having a second terminus and a second flow restrictor installed at or near the second terminus, the second flow restrictor comprising a second open-ended through-channel interconnecting the annulus with the second underground vault, the method comprising:

obtaining, by a system controller, a first flow direction of one or more gases flowing inside the first open-ended through-channel;

obtaining, by the system controller, a second flow direction of one or more gases flowing inside the second open-ended through-channel;

determining, by the system controller, a gas-creating-event is occurring in the annulus of the connection when the first flow direction is toward the first underground vault and the second flow direction is toward the second underground vault; and

alerting, by the system controller, a user when the system controller determines the gas-creating-event is occurring in the annulus of the connection.

17. The method of claim 16 , further comprising:

obtaining, by the system controller, an estimated temperature of a cable within the annulus of the connection;

obtaining, by the system controller, a first channel temperature inside the first open-ended through-channel;

determining, by the system controller, the gas-creating-event is an exothermic event when the first channel temperature is greater than the estimated temperature by more than a threshold amount; and

informing, by the system controller, the user that the exothermic event is occurring when the system controller determines the gas-creating-event is the exothermic event.

18. The method of claim 16 , further comprising:

installing the first flow restrictor at or near the first terminus with the first open-ended through-channel interconnecting the annulus of the connection with the first underground vault; and

installing the second flow restrictor installed at or near the second terminus with the second open-ended through-channel interconnecting the annulus with the second underground vault.