The invention relates to a connector for making a connection underwater, sometimes known as a “wet-mate” or “wet-mateable” connector.
So called wet-mate connectors are used in underwater applications where it is necessary to make a connection, such as an electrical or optical connection, in an environment which is hostile to contact, for example in sea water, and which therefore requires special protection for the components that complete the connection.
One example of an application in which an electrical connection must be made in a harsh underwater environment is that of a well-head in a sub-sea oil well.
After assembly of the well-head on the sea bed it is necessary to connect control cables to sensors and other electrical equipment associated with the well-head. The engagement of a control cable with a corresponding connector on the well-head may be carried out by a diver. The two connectable parts typically comprise a receptacle part and a plug part; the latter which becomes inserted within the former. Each part comprises a substantially cylindrical body part having within it the electrical contact. The electrical contact is typically provided with a protective apparatus to shield it from the surrounding sea water, in order to preserve the integrity of the connector and therefore the electrical connection when subsequently made.
The receptacle part houses a male connecting pin, and the plug part houses the complementary female contact socket. Each of the receptacle and plug is attached by a suitable termination means to respective electrical cables. In use, the receptacle part receives the plug part and as it does so the male pin contact penetrates and makes electrical connection with the female contact socket. Various designs of such connector exist in which there may be a single male pin engaging with a single contact module, or else a plurality of male pins and respective contact modules.
In all cases measures must be taken to prevent the electrical contacts from being exposed to sea water and other harmful matter, such as oil and drilling fluid for example. Maintaining a good seal around the electrical contacts may be necessary for long periods. In order to provide protection for the electrical contacts a number of mechanisms are employed. These include one or more wiper seals arranged to wipe contaminants from the contacts as first a mechanical, and then an electrical, connection is made between the connecting parts. Another common measure is the use of a so called shuttle pin which occupies in an unconnected configuration a position within the female contact module which will subsequently be occupied by the male contact pin when electrical connection is made. In one typical arrangement the plug is generally cylindrical with an outer housing surrounding a generally cylindrical contact module in which is mounted an axially slidable resiliently biased shuttle pin. The receptacle part is also generally cylindrical and houses a cylindrical male connector pin. When the plug is inserted into the receptacle the male contact pin of the latter axially engages the shuttle pin, and as mechanical engagement is continued the male pin axially displaces the shuttle pin though the contact module until electrical connection is made between the male pin and the female contact module. Typically a wiper seal on the plug wipes the male pin as it penetrates the plug.
Since well-heads are frequently located at great depth, the connector parts need to be pressure balanced. This is usually achieved by filling chambers in the connector parts with a pressurised dielectric oil, and providing one or more expandable bladders or diaphragms to accommodate movement of the oil as mechanical and electrical engagement is made and unmade.
As well-head connections become more complex with increasing requirements for monitoring and control equipment, the space available for connectors of the kind described above becomes reduced, and thus the need for more compact connectors increases.