If paralleling gear is not proven, the risk is failed synchronisation, units fighting over load, reverse-power trips and a site outage just when you add new capacity. Your expansion stalls while engineers chase control faults on a live plant.
USP&E as Your Guide for Paralleling Evidence
A beautiful solo load-bank pass on one used diesel genset does not prove a four-set or eight-set house will share load. Synchronizing used diesel fleets means matching voltage, frequency, phase angle, and then holding stable load-share under step changes, motor starts, and fuel-quality surprises. Buyers who treat paralleling as an afterthought discover hunting governors, reactive circulating currents, and nuisance trips exactly when production or hospital loads need MW most.
Audit Your Synchronisers and Load-Share Controls
Start with an inventory of your paralleling gear: synchronisers, load-share modules, governors, automatic voltage regulators, breakers and protection relays. Record make, model, firmware and settings for each genset, because mixed generations of controls often explain why units will not share load evenly.
Test each synchroniser on a dead bus and a live bus, recording voltage, frequency and phase angle at breaker closure. Then run your units together at several load steps and log how kW and kVAr divide between them. Uneven sharing points to governor droop, AVR settings or control wiring that needs attention.
Keep the test records with dates, technician names and instrument details, so your evidence holds up when others review it.
Check Protection Before You Add Capacity
Paralleled sets need reverse-power, loss-of-excitation, over-current and differential protection set correctly for the combined system. Review your relay settings against a current fault study, because adding units raises fault levels and can make old settings unsafe.
Natural gas engines and gas turbine generators added later bring their own controls and protection. Plan how they will communicate with your diesel gear, whether through a common plant controller or hard-wired signals, and test the interface before it carries real load.
Fix faults found in testing before the new capacity arrives. It is far cheaper to correct a governor or relay setting on an idle bus than during a site outage.
Plan the Path From Diesel to Gas Turbines
Many sites move from diesel gensets toward gas as fuel supply allows. Used or new gas turbines and a remanufactured GE Frame 6B are common steps, each with its own synchronising and load-sharing needs. Proven paralleling gear on your diesel fleet makes those steps smoother.
Used gas turbines only beat diesel when gas (or approved dual-fuel pathways) is real at the fence — pressure, quality, interruptibility, and commercial term themes — not when a slide deck invents a pipeline. Dual-fuel hedges may appear on dual-fuel generators while GT shortlists mature on natural-gas turbines.
Keep your diesel units as standby once gas is running. Their proven paralleling gear makes them a reliable backup.
Proof from recent work
Mining · Tanzania
Perseus Mining, Nyanzaga Gold Project
USP&E supplied 28 Cummins KTA50 containerised gensets for the Nyanzaga Gold Project in Tanzania.
Mining · Mali
Barrick Gold, Loulo-Gounkoto
USP&E refurbished the 104 MW power station, rebuilding more than 80 MW of Caterpillar CM32 engines and adding new zero-hour capacity.
Read the case study ›Data centres · USA
Major US hyperscale developers
USP&E refurbished 7 GE Frame 6Bs to zero hours in-house for major US hyperscale developers.
Your path from first call to reliable power
Your 3-step plan: 1. Share your genset list, control details and expansion plan. 2. Get a paralleling audit and path-to-gas options with EPC and O&M. 3. Test, fix, parallel new capacity and hand over the evidence pack.
- Schedule paralleling-gear audits for used diesels; record sync steps, load-share, and which units fail retention criteria.
- Rewrite start order, paralleling acceptance, training, and O&M for the mixed fleet with named roles.
Common questions
Why test paralleling gear on used diesel gensets?
USP&E tests paralleling gear because old synchronisers, governors and load-share controls often fail when units must run together or join new capacity. Untested gear leads to failed synchronisation, uneven load sharing, reverse-power trips and outages just when your expansion starts.
What does a synchroniser test show?
USP&E records voltage, frequency and phase angle at breaker closure on both dead and live buses. The test shows whether each genset closes cleanly onto the bus, and repeated results give you evidence that your synchronisers are safe for paralleled operation.
How do you check load sharing between gensets?
USP&E runs your units together at several load steps and logs how kW and kVAr divide between them. Uneven sharing points to governor droop, AVR settings or control wiring faults, which are then corrected and retested before new capacity is added.
What belongs in a paralleling evidence pack?
USP&E includes the controls inventory, synchroniser test records, load-sharing logs, governor and AVR settings, relay settings checked against a fault study, interface tests with new capacity and dated technician records. That pack shows your gensets are ready to parallel safely.
Why owners choose USP&E
USP&E is a full-service engineering, EPC and O&M company, not a broker. One team designs, builds and runs your plant, so nothing falls between contracts.
Is your fleet putting uptime at risk?
Tell us your load, fuel and timeline. A USP&E engineer will come back with options for Used Diesel Gensets projects, not a sales pitch.