Generator Requirement for a Block Factory in Iraq: Load List and Start Sequence
20 October 2026 · 6 min read
Quick answer
Size the set from a load list, not from a rule of thumb. Add the running load of the machines that draw current together, then find the largest motor that starts while the line is running and cover that step. A QST1200 host is listed at 57.6 kW, a QST1000 at 48.9 kW, and a QS-1200A cuber adds 34.15 kW, so the host is never the whole load.
The generator requirement for a block factory in Iraq is decided by a load list, not by a rule of thumb carried over from another plant. Two buyers can order the same host machine and end up with different sets, because what the generator carries is the line as it is wired on that site: which motors run together, which start under load, and what must keep running when the supply drops in July.
The list is built from the machines, then checked against the way the crew starts the plant. A set chosen from a catalogue page is usually either larger than the job or unable to survive the first restart after a blockage.
Where the load on a block line actually sits
Start with the nameplate of every machine. A QST1200 host is listed at 57.6 kW installed capacity and a QST1000 at 48.9 kW, and both are 17 t machines, so the difference sits in the drives. A QS-1200A cuber adds 34.15 kW on its own and stands on 12,000 × 3,000 mm of floor at about 18,000 kg. The host is not the load.
Add what turns mix into a saleable block: batching and the mixer, the pallet feeder, the stacker, the conveyor drives, the compressor, and the dust and lighting circuits. A line configured for 250,000 pcs per 8-hour shift carries more of these than one at 30,000, and automation changes the list more than tonnage does.
Why the sum of nameplate values is not the generator size
Adding 57.6 kW, 48.9 kW and 34.15 kW produces a number no set has to deliver. Nameplate values are the worst case of every drive at the same instant, and a block line never puts them there together: the vibration motors work for seconds inside a 15 to 25 second cycle, the hydraulic pump holds 31.5 MPa in short pushes, and the conveyors move between pallets. Size on what draws current at the same time, plus the largest motor that starts while the rest runs.
The opposite mistake costs more. Buying on the running load alone ignores starting, and a vibration motor or a hydraulic pump pulls several times its running current for a moment. A set sized that way drops the line at every restart after a jam. The margin is set by the last motor to start.
In what order should the motors be started?
The process fixes the order, and the set is sized on the hardest step in it. Compressor and dust collection first, because they are steady and quiet. Then the conveyors and the batching belt, running empty, so a jam shows before material is on them. Then the mixer, then the hydraulic pump on the host, and the vibration motors last, because they are the shock load and only earn current with a mould full of mix beneath them.
One operator should run that sequence from one panel, with the steps numbered on a plate beside it. When the order lives only in the head of the longest serving man, a night crew starts the vibration motors against a cold hydraulic system and asks the set for a step it was never sized for. The interlock should refuse to start vibration before the pump is at pressure.
What belongs on the essential bus?
Split the board. The essential bus carries what must keep running for the plant to keep making blocks: batching, the mixer, the host, the pallet feed and the curing transfer. Packing, the workshop, yard lighting, the office and the water pumps go on the general bus and die with the grid. That split lets a smaller set carry the productive core instead of the whole site.
The split protects quality as well. A mixer that stops halfway through a wet batch loses the batch, and a host that stops with a full mould leaves a block to break out. On the essential bus the mixer and the host stop together or not at all. The cuber is a judgement call: 34.15 kW is a real load, and a stack on the discharge can be cleared by hand in the morning.
Why must the line never be fed from two sources?
A changeover that lets the board take the grid and the set at the same time is the most expensive fault on the panel. The two sources do not stay in step, and the first parts to fail are the sensitive ones, usually the PLC and the drive boards. The interlock has to be mechanical as well as electrical: break before make, a key that travels with the person working on the incoming side, and a label on both ends of every cable.
Test it as a procedure, not as a habit. Once a month, with the line stopped, transfer to the set, confirm the grid side is dead at the terminals, then transfer back. Write the result and the name of the person who did it. An interlock never tested is a drawing, and the man who trusts a drawing closes a breaker onto a live generator.
How do you refuel without stopping production?
Fuel autonomy is a decision about how long the plant runs without the grid, and it belongs in hours rather than in tank size. A plant on one shift with a supply that usually holds needs a bridge: a tank that covers a shift plus the restart. A plant whose supply goes for a day needs the tank and the refuelling routine written into production planning.
Refuelling while the line runs means a day tank inside a bund, filled from the main tank by a pump, with the fill point outside the generator room and a level gauge visible from the door. Nobody carries a can past a hot exhaust. Keep a spill kit at the fill point and a dipstick log.
The weekly no-load test is the cheapest insurance on the site. Start the set, run it off load for a fixed period, watch coolant temperature, oil pressure, exhaust colour and battery charging, then load it for a few minutes on the essential bus. Record the date, the running hours, the readings and every fault in one book kept in the generator room. A set that has not run for a month fails on the day the grid goes, and the log is the only proof that anyone looked.
What should go into a generator enquiry?
Give the supplier four things. The running load of the line you are actually building, not the sum of the nameplates. The start sequence, with the largest motor that starts against a running line named. The ambient temperature the set breathes in July, in the shade of its canopy, because that sets the derating. And the fuel autonomy you need in hours, with the duty stated: continuous off grid, standby for an unreliable supply.
Leave the electrical design to the supplier and your own engineer. Voltage, frequency, cable sizes, earthing and protection are settled against the local supply and the machine manuals, and a number copied from a catalogue page is how a plant ends up with a set that cannot be connected. Ask for the load list back with each start step marked.
Three numbers travel with the enquiry: the running load of the line, the largest motor that starts while the line runs, and the hours of autonomy you need. Everything else in the quotation follows from those three.
Frequently asked questions
How is a generator sized for a block factory in Iraq?
From a load list, not from a rule of thumb. Add the running load of the machines that draw current together, find the largest motor that starts while the line is running, and cover that step plus the steady load. A QST1200 host alone is listed at 57.6 kW and a QS-1200A cuber at 34.15 kW, before batching and packing are counted.
Can one generator carry a whole block line?
It can, and most buyers are better served by splitting the board. The essential bus with batching, the mixer, the host and the curing transfer keeps blocks coming; packing, the workshop, yard lighting and the office can wait. A smaller set on an essential bus runs closer to its comfortable band than a large set idling on a whole-site bus.
Why does the start order matter more than the total kW?
Because the set does not see a total, it sees a sequence. Vibration motors and the hydraulic pump draw several times their running current at the moment of start, and the largest single step decides whether the line holds. Start the vibration motors last, under a full mould, with the pump already holding 31.5 MPa.
Should the cuber run on the generator or on the grid?
Either works if the decision is taken before the panel is built. At 34.15 kW the cuber is a real load, and a stack left standing on the discharge can be cleared by hand in the morning, so many plants keep cubing on the general bus. Putting it on the essential bus means the set carries it during the largest motor step.
How often should a standby generator be tested?
Once a week off load, plus a short loaded run on the essential bus. Record the date, the running hours, coolant temperature, oil pressure and every fault in one book kept in the generator room. The log is the only proof that the set was checked, and it is what a maintenance engineer reads before trusting the plant through a grid outage.
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