Ultrafast protection for complex and remote circuits and assets
Reflex is Synaptec’s range of ultrafast power system protection for complex and remote circuits and assets.
Reflex detects faults and trips in milliseconds, using passive optical sensors with no power, electronics, or communications at the protected sites. The range includes MCP for mixed overhead and cable circuits and RTP for remote transformers.
Both run on Distributed Electrical Sensing (DES): passive sensors on standard current transformers, read over a spare fibre by a DES Interrogator in the substation.
Get in touch
Aneesh Chandran
Sales Engineering lead
Prasanta Das
Regional Sales Director - India & Gulf States
Dr Oyedotun E. Oyewole
Sales Engineer
Protection for remote circuits and assets
Unit protection needs a current measurement at each end of the protected zone. Inside a substation that is routine. At a cable sealing end on a transition tower, a transformer on a remote tap, or a cable landing point, there is usually no auxiliary supply, no communications link fit for protection, and no time source. Building them costs more than the asset often justifies, so many of these sites are left with slower and less selective protection than the asset deserves.
Reflex keeps every active device in the substation. Passive Secondary Converters (PSCs) on the secondary of standard current transformers encode the current as light on a spare fibre back to a DES Interrogator. The Interrogator reads every sensor on one time base, runs differential protection across the zones you define, and trips, blocks auto-reclose, or passes Sampled Values to your own relays. Nothing at the remote site needs power, maintenance, or recalibration.
Passive sensors on a 110 kV transition tower in Romania
The Reflex range
Mixed circuit protection (MCP)
MCP tells the protection scheme whether a fault on a mixed circuit is in a cable section or on the overhead line, and blocks auto-reclose for cable faults before the breaker opens. Overhead faults reclose as normal.
Remote transformer protection (RTP)
RTP gives unit protection to a transformer far from any substation. The HV line, the transformer, and the LV line each have their own zone, measured from the substation, with the transformer zone run by your choice of 87T relay.
Key benefits
- Unit protection with no substation at the far end. Reflex applies differential protection across cable sections, lines, and transformers whose ends have no relay, power supply, or communications.
- Faulted zone identified in under 10 ms. Mixed circuit schemes in service identify the faulted zone and issue the trip or auto-reclose block in under 10 ms, before the breaker opens.
- More than 60 km from the substation. One DES Interrogator reads sensors along a single fibre, in series or in parallel, to more than 60 km from the substation.
- Nothing to maintain at the remote site. The sensors need no power, batteries, data network, or time source, and are designed for more than 30 years in service without recalibration.
- Works with the relays you have. Dry contacts, IEC 61850 GOOSE, and IEC 61850-9-2 Sampled Values connect Reflex to conventional and digital substations alike.
- Standard current transformers. The sensors connect to any industry-standard CT with a 1 A or 5 A secondary, existing or new, including split-core CTs fitted around cables already in service.
- Nothing to attack at the remote site. Only optical signals leave the substation fence. There are no IP addresses, radios, or electronics at the protected site or remote sensors.
DES Interrogator in a protection panel at Tata Power’s 110 kV Mandale substation, Mumbai
Proven in service
Reflex uses the same DES Interrogators and passive sensors that Synaptec supplies for protection and cable systems monitoring worldwide. In more than 1.5 million sensor-hours of operation, no Synaptec sensor has ever failed in service.
>1.5 million
sensor-hours of operation (October 2026)
<10 ms
to identify a faulted zone on mixed circuits in service
>60 km
from the substation to the furthest passive sensor
In service and in delivery
MCP is in service and in delivery with transmission and distribution operators in India, Europe, and the Middle East, and Synaptec has developed unit protection for multi-ended circuits and busbars with network operators in the UK and Norway.
Monitoring on the same fibre
The passive sensors and DES Interrogators in Reflex also carry Greenlight®, Synaptec’s cable systems monitoring, which measures current and temperature at joints and terminations and gives early warning of developing faults.
Reflex brochure
The Reflex brochure covers MCP and RTP, how each one works, and the service record of the Synaptec passive sensors and DES Interrogators they share, in eight pages.
Talk to us about your circuits and assets
Start with one circuit. Send us the single-line diagram and the fibre route, and we will propose a protection design with a budget price, at no cost. Your preferred contractor or Synaptec’s local partner installs the equipment, and Synaptec commissions it.
Applications
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