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Power Connectors for
Harsh Environments
By
Peter Anderson, Cooper Interconnect
In
the ever-changing world of connectors, there is one steadfast
requirement—transmission of high voltage and current to meet the rising
demand for power. Requirements vary from the smallest nano-machines to
huge offshore drilling platforms and down to underground mines. The
combination of challenging environments and power needs can result in
the acceleration of the negative effects of corrosion, arcing, and
material deterioration. Any slight anomaly in sealing or continuity path
can lead to short service life and downtime for critical operating
equipment. The following are some solutions to connectivity problems in
these and other power applications, with innovative solutions for harsh
and hazardous environments.
Environmental considerations are important to the functionality of an
overall connector system. The efficient transmission of power with
minimal heating, however, requires optimum contact design for the
application. Contact design is dependent on the current being
transmitted and the environmental exposure when the connector set is not
mated or capped. Materials could include standard brass, copper,
beryllium copper, or steel, and plating materials are as diverse as tin,
aluminum, silver, or gold.
Applications and industries demand different interconnect solutions.
Power transmission requires a product that is safe to engage and
disengage, that will not deteriorate during its expected lifecycle, and
that offers a solution that does not let an operator make a mistake.
 In
the military/aerospace arena, the product must not only meet the
application’s environmental constraints, but it must also comply with
rigorous military standards. For ground-based military applications
requiring over 40 amps, MIL-DTL-22992 Class L cylindrical connectors are
available in a variety of configurations supporting various high-power
DC and AC current ranges.
One
example is Cooper Interconnect’s family of Class L heavy-duty power
(HDP) connectors, engineered for safe operation and performance in the
harshest environmental conditions, and supports the most popular
configurations—shell size 32 for 60 amp maximum loads, and shell size 44
for 100 amp maximum loads.
Personnel safety is a primary concern and is achieved by a combination
of recessed socket contacts that provide an arch-quenching chamber and
sequenced contact coupling where the ground and neutral contacts engage
first before the other power contacts. Likewise, when uncoupling, the
power contacts disengage first before the neutral and ground contacts,
providing electrical shock protection to the operator in the event the
cable is separated under load. Further safety is achieved by different
shell keyways and insert rotations resulting in foolproof mating to
ensure that only like electrical characteristics, voltage, current,
frequency, phase and ground are mated together—no mismatching occurs.
 Typically used
in the most extreme weather and climatic environments, the Cooper
Interconnect HDP connector is constructed from a high-strength aluminum
alloy to maximize crush resistance and minimize damage from high-impact
forces. In critical applications, such as field hospitals, command
posts, or remote construction power panels, the incorporation of
multiple heavy-duty gaskets, o-rings, and available dust caps, seals out
environmental threats like moisture, dirt, sand, and dust.
Additional applications requiring high-power connectors include 400 Hz
aircraft ground power or 60 Hz electric motors with the use of the
Safety Service System. Thought of as a “smart circuit-breaker,” this
system protects personnel and electrical equipment by blocking power to
the output terminals and connected equipment when an electrical fault is
detected. It can discriminate between power surges or excessive current
draw caused by shorts or other fault conditions. It can detect when
equipment has been accidentally disconnected or simply turned off. It
can also sense if one or two of the three phases are not conducting,
which indicate cable breakage, inadequate electrical contact between
plug and receptacle, or equipment malfunction.
  Key
features of the Safety Service System include the following:
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Monitors
and controls delivery of 400 Hz 3-phase AC power.
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Control
circuitry uses modern surface mount technology.
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Stops flow
of power to connected equipment in the event of undercurrent and
overcurrent conditions in any or all phases.
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Built-in
delay timer allows for one-person operation.
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Status
indicators visible from a distance.
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E&F
electrical interlock available.
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Available
for 120/208 or 240/480 volt systems.
 For industrial applications that need portable power connections,
Cooper’s Cam-Lok single-pole connectors are insulated in a specially
formulated elastomeric material for water-tightness and safety, and
allow for quick connect and disconnect without tools. Designed to meet
NEC code requirements, the exclusive double-cam principle provides a
positive, vibration-proof connection that is self-compensating for wear.
Additional features include color-coded insulators and safety insulated
panel receptacles. Plugs are available as vulcanized and non-vulcanized
to improve reliability and safety.
The Posi-Lok Power Distribution System brings a new level of safety to
electrical power applications. Designed to meet Article 520-53 Section K
and Article 530-22 Section A (NEC) standards, Posi-Lok’s built-in safety
features require the user to connect or disconnect each plug in
sequence. Protective covers cannot be raised until the preceding plug is
locked into position. The disconnect sequence is reversed. Also, each
plug and receptacle is polarized to eliminate the potential of cross
phasing,
 Posi-Lok plugs feature recessed electrical contacts that are protected
by shatter-resistant insulators and impact-resistant molded sleeves. The
Cam-Lok double-cam principle provides a positive vibration-proof
connection. Just one-third of a turn assures a high-pressure contact
with minimum electrical resistance. The self-wiping action maintains
clean contact surfaces.
Posi-Lok Systems are UL listed and CSA certified in 200, 315, and 400
amps. Optional six-position panels include a double-neutral position to
solve harmonic problems in distribution systems. These systems were
designed with the user in mind. T he 315 and 400 amp panels can be
installed into a standard 19-inch rack. The 200 amp panel requires as
small as a 13.5-inch wide space.
If it is underwater power that is needed, Electro Oceanics (EO)
connectors fit the bill. Rated up to 20,000 PSI open face, this
connector can be located at the bottom of the ocean or a reservoir. Many
custom designs of this connector have been developed for high-power
applications in the underwater environment, including the submersible
pump market, which can handle loads from 20 amps up to 300 amps.
Completely encapsulated in ethylene propylene diene monomer (EPDM)
rubber, these connectors are extremely durable when dragged across the
deck of a ship or ocean floor. Designed to permit underwater plugging
and unplugging with electrical power de-energized, the EO connector can
be used when installing heavy-duty equipment that requires a
“wet-matable” connector. There are no metal surfaces on the plug side of
the connector (other than the contacts) to keep the connectors safe for
handling. Locking sleeves are also available to minimize the risk of
connectors becoming accidentally separated under load. The EO series of
connectors come as straight plug and receptacle, or straight plug and
bulkhead receptacle.
The Burton series of connectors has long been the leader in the undersea
ROV market for their safety and durability. Connectors are constructed
with 316L stainless steel bodies, high-condition copper alloy contacts
with elastomeric over-molded plugs and inserts. To keep things safe, the
Burton connectors have only socket contacts with the pins located on the
receptacle side.
When a customer came to Cooper Interconnect for a critical pump
application, the Burton connector was the solution. The challenge was in
connecting to several 5,000-volt centrifugal pumps that would be
submersed as low as 700 feet and supply city drinking water. A custom
rubber-molded metal shell connector was designed for this harsh
underwater environment. This size 48 connector was constructed of
high-quality 316L stainless steel. Inserts were keyed along with
aligning pins to ensure that connectors mated in the correct fashion.
 Oil platform and exploration equipment requirements differ widely with
respect to the diversity of applications, power, and environments.
Submersible connectors for wellheads are required to seal the external
environment from the inner workings of the well while operating at 5,000
volts. High-power connectors are required ranging from 60 to 1,135 amps
to operate a variety of equipment on the rigs.
Roughneck High Amperage Connectors offer the ultimate performance for
safety and reliability. Specially made to handle a variety of drilling
applications, Roughneck products can be quickly and safely connected to
the switchgear or the AC/DC sides of an SCR package and carry power to
mud pumps and traction motors.
 The Roughneck is simple to connect and disconnect: No tools of any kind
are required to connect or disconnect the connector to the receptacle. A
latching device locks the halves together, eliminating the possibility
of accidental disengagement, which can cause disruption of service and
electrical shock hazards. The locking device is designed to permit
insertion of a lockout/tag out device to provide additional security or
the ability to padlock. Also, the insulator extends past the ends of
both male and female contacts for complete safety. Male contacts are
equipped with Cam-Lok’s Safe Front Insulated Tip to minimize potential
shock hazard.
The Burton ESP penetrators and cable assemblies are available for
virtually every wellhead configuration, including most downhole packers.
 ESP Penetrator features include the following:
The Quik-Loc Series
of connectors can handle power needs for mining operations. Constructed
of neoprene and sturdy neoprene-covered alloy castings, Quik-Locs are
watertight and corrosion resistant. Couplers with pin-and-groove design
allow for quick connect/disconnect, and are also field-attachable
requiring no special tools. Electrical parameters include #8 AWG through
500 MCM cable, and up to 600 volts/625 amps, or 1,000 volts/500 amps.
These are just some of the innovative products and services that meet
the high-amperage connector needs in the military and industrial
markets. Products with the most stringent requirements can receive
customized attention by selecting a connector manufacturer skilled in
this area of the industry.
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