Oil Ring Main Units...
Depending on our customers' needs, Jocastro can supply fully automated oil equipment using a combination of linear motor driven actuators, auxiliary relays and a range of tele-control options including a wide variety of Remote Terminal Units (RTUs) and communication protocols. All designed to satisfy Utilities' latest system supervisory and control requirements.
Various Remote Control and signalling options are available including non-intrusive fitting options, which allow the fitting of the actuators and associated equipment with the unit still live, thus maintaining the integrity of the supply.
Remote tripping of fuse switch
Remote opening and closing of ring switches
Remote position indication
Earth Fault indication.
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FRMU Fused Ring Main Unit
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FRMUE Fused Ring Main Unit Extensible
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EFS Extensible Fuse Switch
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EOS Extensible Oil Switch
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DEOS Double Extensible Oil Switch
Trident Fused Oil Ring Main Unit up to 15.5kV
with automation and remote control options





Lucy Switchgear has over 100 years of experience within the power distribution industry. Its Trident range of oil insulated ring main units (RMUs) has been developed over a number of years and is a leading performer in the global market. For use in both rural and industrial settings, it can be positioned in the most extreme conditions: ambient temperatures from -10°C to 55°C, humidity of up to 100%, corrosive regions, oil fields and other hostile environments.
Corrosion Protection
The main body of the unit is fabricated from 4mm steel which
is shot blasted, zinc sprayed and then coated with an epoxy
powder paint finish for durable outdoor and indoor use.
Maintenance
The Trident range of ring main units requires very low levels
of maintenance. Under normal conditions a routine inspection
is required at an interval of once every seven years.
Key Features
- Ratings up to 15.5kV
- Long service life
- Low maintenance
- Outdoor
- Isolation in oil
- Interlocked for safe operation
- Padlocking facilities
- Fully extensible
- Robust sheet steel housing
Operation
Mechanism
The operating mechanisms are of the independent manual
spring type for both main and earth switches ensuring
that speed of operation is independent of the operator.
Ring Switches
Ring switches are fault make, load break three position
type ‘ON’, ‘OFF’ and ‘EARTH ON’.
Fuse Switch
The fused TEE OFF is of the fault make, fault break, three
position type ‘ON’, ‘OFF’ and ‘TRANSFORMER EARTH ON’.
The fuse switch has a double isolation feature for additional
operational safety.
Safety
The unit has been designed to ensure maximum operator
safety. Live parts are contained within an earth sheet steel
enclosure. Cable termination boxes are located away from
the operator – to the side and the rear, to ensure operator
safety at all times. A single line diagram and mechanical
indicators exist on the front of each unit to aid user safety
and interlocks on all switch positions prevent incorrect
operation. In addition padlocking facilities are provided
for all positions and can be equipped with neon voltage
indicators (live cable indication), interlocked cable test
facility on tee-off and Castell interlocking.
Automation
The Trident range of oil ring main units can be fully
equipped with automation features to address customers’
requirements for remote monitoring and control.
A variety of automation options are available:
- Retrofitable motorised actuator, available as a
single LH or RH or double ring switch configuration.
Status indicators for the ring switches are also available.
The non-intrusive nature of the retrofit assembly negates
the need to shut down the unit whilst the installation
takes place. - The tee-off fuse switch can be fitted with a shut trip
for remote tripping and auxiliary contacts for
remote indication. - A purposely designed Remote Terminal Unit (RTU)
mounting bracket can accommodate our Gemini-
RTU on either the right or the left hand side of
the Trident RMU. - Earth fault passage indicators complete the picture
by providing crucial information on the location of
earth faults in a MV network split ring.
Our Gemini range of automation products and systems
ensure an integrated solution, so that the Trident RMU
can be monitored and controlled by most utility
NMS/SCADA systems.
In essence, our automation solution is a factory built automation package that can be ready for immediate installation with minimal on-site works.
Accessories
Lucy Switchgear has developed a number of accessories
that can be added to a Trident RMU providing flexible
solutions for our customers.
- Remote tripping
- Ring switch actuators
- RTU mounting bracket
- Earth fault indicators
- Test plug devices
- Busbar connection
- Cabling
- End cap kit


