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Temporary Power Restoration Products
At Bridgeport Magnetics Group, we help utility companies and linemen achieve fast temporary power restoration. Our PowerBack and Trident toroidal autotransformers deliver reliable balanced 120/240V service in minutes, with superior portability, efficiency, and rugged reliability for emergency outage response.
Temporary Power Restoration at the Meter in Minutes
Bridgeport Magnetics’ temporary power restoration autotransformers (PowerBack and Trident) regenerate a missing hot leg or neutral directly at the meter socket – restoring full balanced 120/240V or 120/208V service within minutes while permanent repairs are scheduled.
Designed by linemen, for linemen in collaboration with utilities, every PowerBack and Trident unit is manufactured in Shelton, Connecticut with a fast 1–2 week lead time. Built with high-efficiency toroidal cores, they include voltage and amperage monitoring plus redundant 2× trip overcurrent protection for safe, confident deployment in the field.
Our Customers
PowerBack & Trident Models
Compare ratings, enclosures, and features across the lineup.
| Trident | Powerback-Lite 15KVA | Powerback-Lite 20KVA | Powerback 15kVA | Powerback 20kVA | Powerback 30kVA | Powerback 50kVA | |
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| High Efficiency Toroidal Auto Transformer | 20kVA (2x10kVA) | 15kVA | 20kVA | 15kVA | 20kVA | 30kVA | 50kVA |
| Recommended Service | 100A (oneAuto) 200A (twoAuto) | 150A | 200A | 150A | 200A | 320A | 400A |
| Circuit Breaker | 2x50A | 125A | 160A | 125A | 160A | 250A | 400A |
| (Dual Protections) Shunt Trip Temp. degC | NA | 105 | 105 | 105 | 105 | 105 | 105 |
| Corded Meter Adapter Included | 200A | 200A | 200A | 200A | 200A | 320A | No meter adapter - Cam-Lok kit, 10 ft 1/0 & 3/0 leads, 9-pc Flood-Seal/tinned whips. |
| Input/Output Voltmeters | Yes | Yes | Yes | Yes | Yes | Yes | NA |
| Integrated GFI with Defeat Switch | Optional | Optional | Optional | Optional | Optional | Optional | NA |
| GPS Tracking | Optional | Optional | Optional | Optional | Optional | Optional | Optional |
| Enclosure Type | Resin Case | Resin Case | Resin Case | NEMA 4 Stainless | NEMA 4 Stainless | NEMA 4 Stainless | NEMA 4 Stainless |
| Grounding | No Grounding Required | No Grounding Required | No Grounding Required | YES | YES | YES | YES |
| Dimensions (inches) | NA | 29 x 22 x 13 | 29 x 22 x 13 | 29 x 22 x 13 | 29 x 22 x 13 | 29 x 22 x 13 | 46 x 35 x 20 |
| Wheels (Diameter x Width) | NA | 10.5" x 3" | 10.5" x 3" | 10.5" x 3" | 10.5" x 3" | 10.5" x 3" | 12" x 4.5" |
| Weight (lbs.) | 45 / Auto | 91 | 110 | 120 | 140 | 220 | 290 |
A toroidal core makes Power-Back dramatically lighter than conventional E-I lamination units, so a single lineman can position it at the meter pan without a hoist or a second set of hands.
Two independent trip paths: transformer
winding temperature and overcurrent. If either limit is reached,
PowerBack disconnects itself. Leave it on-site with confidence.
Puncture proof / airless tires for rough deployments –
driveways, gravel, mud, and storm debris.
Connect at the meter in one turn. The Power-Back meter adapter installs fast and includes a neutral – so you restore service in minutes instead of running temporary above-ground conductors.
Every Power-Back is Manufactured in Shelton, Connecticut, with a 1–2 week lead time. No import delays.
When a Single Leg Fails, Don't Leave Customers in the Dark
An open hot leg or neutral – caused by a storm, damaged underground cable, or equipment fault – can drop a customer’s service even when the upstream transformer is intact. Locating and repairing the fault often takes days.
Temporary power restoration autotransformers (also known as add-a-phase or service-saver devices) solve this by connecting between the meter socket and the meter to quickly regenerate the missing leg and restore full balanced 120/240V or 120/208V service.
PowerBack and Trident systems restore load current on an open hot leg up to their rated capacity and full service on an open neutral up to their neutral current rating – giving your crews the flexibility to schedule permanent repairs on their own timeline instead of working under emergency pressure.
When wheeling a cart isnt an option - rough terrain, flooded ground, easements, backyards - the Trident goes where a wheeled unit can't.
The first handheld modular toroidal restoration unit at <50lb weight – purpose-built with line crews and Unions with strict weight restrictions
~45 lb per transformer plus a 9 lb control unit. Built for easements, backyards, gravel, and flooded ground – restore service where wheeling is impossible.
A new weatherproof enclosure protects the unit through restoration in any conditions.
Connect at the meter in one turn. The Power-Back meter adapter installs fast and includes a neutral – so you restore service in minutes instead of running temporary above-ground conductors.
Every Trident is Manufactured in Shelton, Connecticut, with a 1–2 week lead time. No import delays.
Back online in days, not weeks.
PowerBack and Trident temporary power restoration autotransformers – developed hand-in-hand with utility line crews, engineered and built in Shelton, Connecticut.
Frequently Asked Questions
What is a temporary power restoration autotransformer?
A temporary power restoration autotransformer is a secondary device – also called a service saver, add-a-phase, add-a-leg, phase restoration unit, auto cart, or Servisavor-style unit – that regenerates a missing hot leg or missing neutral on single-phase 120/240V or 120/208V service. Two of the three conductors still have to be good. PowerBack (wheeled), PowerBack Lite, and Trident (carry-in) restore at the meter. The 50 kVA PowerBack restores a multi-meter cabinet or pedestal on the incoming secondary. Customers stay online while the underground repair is scheduled.
How does PowerBack connect to the service?
Most PowerBack, PowerBack Lite, and Trident units connect at the meter. Isolate the faulted conductor, remove the meter, land the single-turn adapter (ring-type or ringless; CL320 on the 30 kVA), set the meter back on, and energize. Neutral is in the adapter. No temporary overhead.
The 50 kVA PowerBack does not use a meter adapter. It lands on the cabinet or pedestal secondary with a Cam-Lok kit: 10 ft 1/0 and 3/0 leads, then a 5 ft Flood-Seal or tinned whip.
What's the difference between PowerBack and Trident?
Same electrical job: restore a missing hot or a missing neutral. PowerBack is the wheeled service saver for sites a cart can reach (Lite at 91–110 lbs, stainless 15–30 kVA, 50 kVA for multi-home cabinets). Trident is the 45 lb one-person carry-in service saver for stairs, alleys, gates, and finished yards. Designed by linemen, for linemen.
Can PowerBack restore an open neutral as well as an open hot leg?
Yes. PowerBack and Trident restore a missing hot or a missing neutral. Two conductors must still be good. They cannot restore a hot and the neutral at the same time on the same service. Size the unit to the ticket: 15 kVA / 150A, 20 kVA / 200A, 30 kVA / 320A, 50 kVA / 400A multi-home, or Trident 100A / 200A by module count.
Do the units include monitoring and safety protection?
Yes. Protection is built for a unit that may sit for days, not only for the minute you close the breaker.
PowerBack and PowerBack Lite (wheeled) use dual-trip protection – two independent paths to the same breaker:
- Path 1 – overcurrent. A model-rated breaker opens on high current (short or severe overload): 125A on 15 kVA, 160A on 20 kVA, 250A on 30 kVA, 400A on 50 kVA.
- Path 2 – winding temperature. A 105°C sensor at the transformer – not on the cabinet wall – shunt-trips that same breaker if the core and copper overheat while current is still under the breaker rating. A breaker alone does not see slow heat from load, blocked airflow, ambient temperature, or solar export.
If either path fires, PowerBack disconnects itself. 15–30 kVA models also have a digital input/output voltmeter so the crew reads 120V hot-to-neutral and 240V hot-to-hot before they leave. Optional GFI (defeat switch) and optional GPS.
Trident uses per-module protection instead of the 105°C shunt trip. Each 10 kVA autotransformer has its own 50A breaker. If only one module is installed and the house needs more than that module can carry, Trident shuts off – protecting the transformer and the home. Built-in voltage and current monitoring is the second trip path. Confirm the reading at the control unit before you leave.
Are these built in the USA, and what's the lead time?
Yes – every PowerBack and Trident temporary power restoration autotransformer is designed, wound, and assembled in Shelton, Connecticut. This domestic manufacturing provides reliable 1–2 week lead times with no import delays, helping utilities maintain strong fleet readiness.
Who uses temporary power restoration autotransformers?
Temporary power restoration autotransformers are primarily used by electric utilities, line crews, and contractors during storm recovery, underground cable faults, planned maintenance, and emergency outages. They are especially valuable for residential, multi-family, and light commercial services where fast restoration improves SAIDI/SAIFI metrics and customer satisfaction.
How long can a temporary power restoration unit stay connected?
Temporary power restoration can be installed days to a few weeks – until the permanent repair is scheduled and completed. That is the job. Confirm voltage before you leave. Dual-trip on PowerBack, and per-module overcurrent on Trident, watch the unit while it sits. Remove it when the cable or connector is fixed.
Can these units be used on a home with rooftop solar?
Yes, on 120/240V or 120/208V single-phase service, if two conductors are still good and the install follows your utility’s procedure.
Best practice is to isolate or disconnect the solar equipment before you leave the unit on-site. A service saver does not block reverse power. Once voltage is restored at the meter, the inverter may stay online or reconnect. Export then adds current through the unit and extra heat in the windings.
If the array stays connected: treat export as added load, size the unit up if needed, and confirm voltage and current before you leave. Do not assume the inverter is off just because one utility conductor is open. If the unit trips, do not reset and walk away – check whether the array is exporting. PowerBack dual-trip (breaker + 105°C winding shunt trip) is the extra layer on a solar house that may sit for days.
