A genset sync panel links two or more sets into one paralleled source that the site reads as a single supply during a grid loss. Tesla Power wires that panel from the commissioning scheme rather than from a generic drawing, then states the voltage and the frequency basis so two supplier quotations can be compared step by step before an order is placed. The panel settles three things at once: the load share between sets, the breaker sequence that guards the bus, and the log the controller keeps through each transfer. Build it from the paralleling scheme rather than from a catalogue page, because a catalogue page misses the step that decides the bus. Three signals decide the sync before the average does, and none of them is the largest in kW terms. Voltage removes capacity before any load is connected, and that removal sits in the protection table rather than on the plate. A parallel profile needs one figure a single set does not: the total the bus must carry when the second set starts against a load the first already holds, and the steps below follow the scheme rather than the estimate.
- Land the voltage and frequency sense on each set, because a missing sense leaves the bus unprotected and hides the step.
- Add the load share line to the running total, since that step decides the bus more often than the average day does.
- Set the protection from the scheme at the set, which sits above the site average and moves the trip point down.
- Keep the scheme beside the rated sets we export, so a supplier quotes against a drawn figure rather than an estimate.
What does a genset sync panel do on a parallel bus?
The panel decides three things at once: the load share between sets, the breaker sequence that guards the bus, and the log the controller keeps. None of the three follows from a single nameplate, because that plate describes one set at rest rather than two sets in step, and Tesla Power reads the scheme instead. A bus fed by two 1000kVA sets may carry 900kW from one and 700kW from the other after a transfer, and the second figure is the one that decides the breaker setting. A genset for a parallel bus that is sized on the single set runs at light load for most of the year.
The reason is that a diesel engine responds to a step rather than to an average. A panel tuned on the average lets one set carry the peak while the other idles, and a panel tuned on the transfer shares the step as the scheme intends. The profile resolves that argument, because it shows how the share moves and how often it returns. Most genset manufacturers quote a single set and leave the panel to the buyer, which is where two offers stop being comparable.
How is the load shared between two sets?
Share it from the scheme rather than from a catalogue page. A controller that samples the current every ten milliseconds for a working week gives the share at 672 points, and four of them decide the answer: the highest fifteen minute share, the highest one minute share, the longest run above 70% of the peak, and the lowest sustained share during a shift.
Where a recording is not possible, the site log and the production schedule carry most of the same information on the duty. Shift patterns show when the large motors run together, the maintenance book shows how often a compressor restarts, and a set in parallel operation shares the step differently. Yangzhou Tesla Power asks for both when a tender names a set without a scheme, because the two together close most of the gap a single plate leaves open.
| Sample | What it shows | Why it changes the answer |
|---|---|---|
| Highest fifteen minutes | The steady ceiling the bus holds | Sets the rating before any correction |
| Highest one minute | The step taken at transfer | Decides the breaker setting on the panel |
| Longest run above 70% | How hard the engine is worked | Drives the cooling and the service interval |
| Lowest sustained figure | How far the load falls | A run below 30% loads the exhaust |
The fourth line catches more buses than the other three together. A bus that carries 1600kW for an hour and 250kW for six leaves unburned fuel in the exhaust, and the deposit shows on the injector tips long before it shows on the hour meter.
Which signals decide the synchronising step?
Three signals decide it, and none of them is the largest in kW terms. The first is the voltage sense, because a mismatch of a few volts draws circulating current for the whole run. The second is the frequency sense, since the set that lags the bus pulls the share to itself and the panel sees the total at once. The third is the phase angle at the breaker, because the angle lasts long enough to trip the protection if the bus is closed at the wrong moment.
A 1000kVA frame at 0.8 power factor carries 800kW, so 1000kVA × 0.8 = 800kW is the figure the bus has to stay under at that factor, and two frames in parallel carry 1600kW on the same basis. A 500kVA frame started against a 1000kVA bus adds roughly 400kW of apparent demand for two seconds, which the alternator meets by dipping rather than by delivering. The 500kVA set with the ATS option carries that step on the same 0.8 factor.
- A voltage mismatch draws circulating current for the whole run.
- A frequency lag pulls the share to the slower set.
- A wrong phase angle at close trips the protection.
The dip recovers as the excitation responds, and the question is whether the bus tolerates it. The commissioning sheet sets out the tolerance for common loads, and Chinese genset suppliers usually quote a dip figure only when a buyer asks for one.
How does the breaker sequence protect the bus?
The sequence removes capacity before any load is connected, and the removal is stated in the protection table rather than on the plate. A bus rated to clear a fault in 0.1 second loses roughly 3% of its margin for every 10 ℃ above the reference, so a 1000kVA bus loses about 6% of its margin between 40 ℃ and 45 ℃. The site then plans against the corrected value rather than the plate figure.
The alternator compounds it. Air density falls with height, and a naturally aspirated engine loses about 4% of its rating per 1000m, while a turbocharged engine loses rather less because the compressor compensates for part of the drop. Tesla Power Equipment states both bases on the offer, because a correction applied in sequence gives a different answer from one added on top. The figure belongs on the offer sheet beside the rating, where a buyer can read it against the site conditions.
What does the controller log during a transfer?
The controller keeps one record a single set does not: the share at the moment the second set closes. A bus that carries the site for two hours needs a log and a trip margin sized on two hours, and a bus that carries it for three days needs both sized on three. The rating class follows the same reasoning, because a standby class allows a limited number of hours a year and no continuous overload.
The hours figure decides more than the log. A site that expects 40 hours a year reaches the calendar limit of a warranty schedule long before the hour cap, and a site that expects 2000 hours closes the cap inside a season. Tesla Power writes the expected hours into the offer beside the class, so the two lines are read together rather than as a rating and a note, which keeps a genset in a parallel bus honest about its duty.
Where does paralleling go wrong on export sites?
The first error is a scheme copied from an earlier project in a cooler country. The equipment matches, the ambient does not, and the correction is left off the figure on a set for a data centre as readily as on a set for a mine site. The second is a proposal written from a standard sheet, which quotes a reference figure without the site basis and therefore reads higher than the site can use on the day the load steps. Both errors are invisible in a price comparison, and both change the class rather than the frame.
The third is a panel that stops at the main board and ignores the loads a tenant adds two years after handover. A chiller fitted later changes the share, and the offer is then read as a promise rather than as a figure with a basis. Suppliers who ask for the scheme before quoting close that gap, and the ones who quote from a catalogue leave it open, which is why a standby set should be quoted against a drawn scheme.
A tender that names the rating, the ambient, the altitude and the expected hours gives every bidder the same starting point. That is the difference between four offers that can be compared and four prices that cannot, and the difference shows at the transfer rather than at the invoice.
Which records prove the set was commissioned in parallel?
Three records carry the proof. The site recording, with the date and the instrument named, shows what the load actually did. The commissioning sheet shows the share the bus carried at handover and the ambient at the time. The annual load test shows the share a year later, and the two together show whether the profile has drifted.
The value of the third record appears slowly. A site that adds load over five years reaches the bus limit quietly, and the first sign is a trip on the largest motor rather than a rising bill. A load test at 80% of the rating for two hours each year catches the drift while the answer is still a setting rather than a new frame, which is the practice our own test bay follows for every export order.
How should a buyer compare two offers on the same bus?
Compare the basis before the price. Two offers on the same bus should state the same four figures: the rating, the class, the ambient and the altitude. Where one offer states a figure without a basis, the comparison stops there, because a higher number on a lower basis is not a larger machine. The 2018 ISO 8528-1 rating bands are the ones both offers have to name, and the the ISO 8528-5 transient limits add the step behaviour a parallel bus follows.
A scheme for a data hall adds a fifth figure, which is the step the uninterruptible supply applies when it hands over. A scheme for a mine site adds a different fifth figure, which is the restart group after a power cut. Both belong on the enquiry, and both change the class rather than the frame, which is why a supplier should answer the four items inside the quotation.
Ask for the corrected figure in writing, and ask which document the supplier will issue with the set. A supplier who answers with a schedule can be compared with a second supplier; one who answers with a number can only be compared on price. Tesla Power answers the four items inside the quotation, and the reply arrives as a schedule for that reason.
What does the panel look like on a container build?
A container build carries the same panel as an open frame, and the enclosure changes the correction rather than the load. The intake sits lower, the air is warmer inside the box, and the louvre free area sets the volume that reaches the radiator. The 1250kVA parallel build carries its derating chart beside the plate for that reason, because a genset sync panel for export duty shares the same enclosure logic as a single set.
The container adds one more figure to the scheme, which is the ambient inside the box rather than outside it. A site at 40 ℃ outside may see 47 ℃ at the intake, and the correction follows the higher figure. a set for a site with a container build needs that number on the enquiry, because the answer changes by about 2% per degree at that point, and the practice came from a coastal site where the box ran 8 ℃ above the yard for most of August.
Our own test bay measures the intake figure with the doors closed, which is the condition the set meets in service rather than the condition it meets on a bench, and the Yangzhou production works records that figure for every order. We record the figure with the load bank at 80% of the rating and the ambient noted beside it, and the record travels with the set so the buyer can read it against the site.
Which paperwork proves the protection was set?
The offer sheet carries the corrected figure, the data sheet carries the basis, and the nameplate carries the class. Three documents, and a buyer who reads only the third sees a number without a reason. conformity assessment for the sync panel then checks that the plate matches the file rather than the quotation, which is the step a customs inspection performs first.
Ask for the correction as a line on the offer rather than as a paragraph in a covering letter, because a line survives a change of salesperson and a paragraph does not. Tesla Power Equipment prints the ambient and the altitude beside the rating for that reason, and the practice has settled more than one disagreement at handover when two offers were read against the same scheme.
The plate itself carries the class, the frequency and the power factor, and each field is checked at the port against the file. A plate that omits the class leaves the rating open, which is the gap a customs inspection finds first. Send the scheme and the site sheet to our export quotation desk, and the reply comes back as a schedule with the correction already applied and the quotation built on the drawn figure.
Frequently asked questions about a genset sync panel
A working week covers most buses, because it captures the weekday peak, the weekend trough and at least one restart cycle. A single day misses the shift pattern that produces the peak. Where a week is impossible, record the two hours around the largest restart and the two hours after a transfer, which still catches the step the bus is sized on.
It should, and 20% covers most steady buses. The margin is a decision rather than a rule, because a set that runs at 45% for years meets its own failure mode. Take the margin from the scheme: a bus with a large motor start needs more than a bus with a resistive load, and the margin should sit in the recorded figure rather than on the plate.
It is the share of a connected group that runs at the same moment, and it is applied group by group rather than to the whole bus. Lighting runs at about 0.9, socket outlets at 0.4 and welding sets at 0.3 on a busy shift. A total built without factors overstates the load by a wide margin and oversizes the frame that follows.
It does, because the alternator is rated in kVA and the load is often quoted in kW. A 800kW load at 0.8 power factor needs 1000kVA, and the same load at 0.95 needs less capacity on the same alternator. The factor is measured rather than assumed on a bus with drives, and it is written into the offer beside the rating.
They can, and the arrangement gives redundancy that a single frame cannot. The cost sits in the switchgear and in the load sharing controller, and the maintenance work doubles. Two sets also change the step behaviour, because the second frame starts against a load the first already carries, which is the trade a buyer should weigh before quoting.
The current recorded at the rating point during the commissioning run, taken with the ambient noted beside it. A figure without the ambient cannot be compared with the factory test. Tesla Power issues that record with the set, and it is the document a warranty question is read against when the load has drifted two years after handover.