Internal fault detector and methods of using same

A fault detector for indicating the occurrence of a rapid pressure rise within a housing of an electrical device, the fault detector comprising:

• a barrel;
• an actuating mechanism in fluid communication with an interior of the housing, the actuating mechanism comprising:
• a chamber, the chamber being sealed and having an orifice communicating between an external environment of the chamber and an interior of the chamber;
• and
• an actuating member movable in response to a pressure differential between the interior of the housing and the interior of the chamber, the actuating member comprising a spring constant of 5 lbs/in or less;
• and
• a plunger within a bore of the barrel, the plunger biased forwardly in the barrel and normally retained in an armed position by the actuating member;
• wherein, when the pressure differential exceeds a positive threshold value, the actuating member is moved and thereby permits the plunger to move forwardly into a triggered position.

A fault detector for indicating the occurrence of a rapid pressure rise within a housing of an electrical device, the fault detector comprising:

• a barrel;
• an actuating mechanism in fluid communication with an interior of the housing, the actuating mechanism comprising:
• a chamber, the chamber being sealed and having an orifice communicating between an external environment of the chamber and an interior of the chamber;
• and
• an actuating member movable in response to a pressure differential between the interior of the housing and the interior of the chamber to cause the actuating member to move from an unactivated configuration to an activated configuration;
• a plunger within a bore of the barrel;
• and
• a locking member having a first position and a second position, wherein in the first position the locking member is positioned to restrain forward movement of the plunger in the barrel and to prevent a transfer of forces applied to the plunger to the actuating member and in the second position the locking member is positioned to allow forward movement of the plunger, the plunger being initially retained in the unactivated configuration by the locking member when the locking member is in the first position and the plunger being movable forwardly within the bore of the barrel when the locking member is in the second position;
• the locking member being movable from the first position to the second position in response to movement of the actuating member from the unactivated configuration to the activated configuration.

A method of activating an internal fault detector, comprising:

• allowing a rapid pressure rise to actuate a pressure sensor;
• moving a retaining pin in response to the actuation of the pressure sensor to allow a locking member to move from an unactivated configuration to an activated configuration;
• and
• allowing a plunger that is retained by the locking member when the locking member is in the first position to be forwardly displaced by the biasing force when the locking member is in the second position to provide an indication that a rapid pressure rise has occurred;
• wherein the locking member in the unactivated configuration is configured to prevent a transfer of forces applied to the plunger to the retaining pin.

A fault detector for indicating the occurrence of a rapid pressure rise within a housing of an electrical device, the fault detector comprising:

• a barrel;
• an actuating mechanism in fluid communication with an interior of the housing and configured to release an actuating member in response to a rapid pressure rise within the housing;
• a plunger within a bore of the barrel, the plunger biased forwardly in the barrel and normally retained in an armed position by the actuating member;
• and
• a static seal having a first end fixedly retained on the plunger and a second end fixedly retained on the barrel, the static seal having a central portion that permits relative movement of the plunger and the barrel when the fault detector moves from an armed to a triggered configuration while maintaining a seal between the interior of the housing and an external environment of the housing.