Diesel or Electric Drive for Block Machines in Iraq: Matching the Plant to the Grid

The diesel or electric drive for block machines in Iraq is settled at your own site, before the order, not by a preference for one fuel. Two measurements decide it: the hours of grid supply you actually receive in a working day, and the current the largest motor pulls in the first second after the start signal. A plant with a steady supply through a full 8 h shift runs all-electric. A plant that gets less than a shift carries a generator, sized on what the machines draw together.

How many kW does a block machine pull from the line?

Start with the nameplate, because that is the figure the factory prints and the figure the generator has to answer. The QST6-15 is listed at 34.4 kW installed. The QST1200 is listed at 57.6 kW, and the QST1800 at 104 kW. On the paver side the static presses run from 46.9 kW on the QS600 to 108.2 kW on the QS1500 bidirectional, and the QS-1200A cuber adds 34.15 kW of its own.

Those are installed capacities: every motor on the frame at full rating, the vibration motors, the hydraulic pump, the pallet feed, the skip hoist. They never run together at nameplate, and none holds nameplate through a shift. That gap is why an average is the wrong number. A QST1200 sitting under its rating still has a vibration motor reaching full speed in a fraction of a second, and the supply sees a current spike.

The rest of the plant sits on top. A mixer from the JS500 to JS1500 range, the conveyors, the batching load cells and the pallet handling draw from the same board. A mobile mixing station is listed at 65 to 100 kW for 25 to 75 m3/h of theoretical output, a load comparable to a second block machine. A plant quoting 104 kW for the machine alone can put far more than that on the transformer.

Why does a generator sized on average load trip at the first motor start?

Because a generator answers current, not energy. The vibration motor on a QST1800 runs at 3,800 to 4,500 times per minute, and reaching that speed takes a starting current several times the running current, held for the seconds the rotor accelerates. In that window the set sees a demand far above its rating, voltage sags, and every contactor on a low-voltage coil drops out at once. The line stops, and the operator reports a generator fault when the fault is a sizing error.

The hydraulic pump adds a second surge: a press at 31.5 MPa puts the pump on load at the start of every cycle, and a 15 to 25 s cycle repeats it all shift. Take the largest motor that starts while the line runs, add the load already running, and compare the total with the continuous rating of the set, not its peak label.

That gives the working rule: size on the machines that must run at the same time, and keep the press and the cuber on separate circuits. A start on one then does not drag the other down, and the electrician can isolate the cuber for service while the press keeps cycling.

What has to be measured at the site before the order is signed?

Four readings decide the arrangement, and all four come from your site rather than a catalogue. Take them across a normal working week, not a good day.

• Grid hours: how many hours of supply you receive in a working day, and whether they arrive in one block or in pieces.
• Voltage under load: the reading at the machine board while the biggest motor starts, not the reading at the transformer with the plant idle.
• Distance from the transformer: cable length and cross section, because a long run at a heavy start loses voltage in the cable before the motor ever sees it.
• Shift pattern: whether a second shift is realistic on the supply you have, or whether it would run entirely on the generator.

The curing line makes its own power choice

The QSRGY finger-car line offers two arrangements for the cars that carry pallets into the curing yard. The track-power version feeds 380 V AC to the line and steps it down to 36 V DC on the running rail, so the car collects current wherever it stands. The battery version uses a 36 V lithium pack with a BMS and an automatic charging pile.

Length and layout settle the choice. A short straight run suits the rail: no pack to change, no charging window. On a long curing line the rail runs the length of every bay, with joints, supports and a step-down point, and every metre is a cable you own and a joint that can fail. A battery car removes those runs, and the charging pile sits at one point. The QSDJ rack-curing line does the same, with a lithium-battery transfer car and an RS-485 wireless network.

Count the bays before deciding. A yard with a few bays and one shuttle is a rail job. A yard laid out around pallet count, with rows running away from the machine and the 1,400 mm stack limit of the QS-1200A, is a battery job: the rail grows with every bay, the pack does not.

What a diesel set adds to the running cost structure

A generator is not a single line on a cost sheet. It brings four categories that stay with the plant for as long as the set runs.

• Fuel handling: storage, delivery, filtering and the labour to move it to the set, plus the risk of a contaminated batch reaching the injectors.
• Service interval: the set is serviced on running hours, so every production hour also counts toward the next service, whether the grid was available or not.
• Noise and siting: the set needs a foundation, an exhaust route and a distance from the nearest building that the local authority accepts.
• Operator time: someone starts it, watches the gauges, logs the hours and switches the plant back to the grid when the supply returns.

How is the drive arrangement decided in one page?

Put the grid hours beside the shift length first. If the grid gives less than a full shift, the generator is part of the production line, so size it on the installed capacity of the machines that must run together: block machine, mixer, conveyors and, if it runs in the same window, the cuber. Not the whole plant, not the average draw, because an average never starts a motor.

Then split the board. Press and cuber on separate circuits with separate protection, so a start on one does not take the other down and a fault can be isolated without stopping the shift. Settle the curing line on its own terms: rail where the run is short, battery cars where the yard is long. Write the site readings into the order.

A plant that does this buys one set of the right size instead of two of the wrong one, and keeps the press cycling while the grid is down. A QST6-15 at 34.4 kW runs on a modest set. A QST1800 at 104 kW does not, and that difference is why you measure first.