Diesel or Electric Drive for a Block Machine in Syria: Load and Fuel Logistics

Diesel or electric drive for a block machine in Syria comes down to two things: how the load is built and how the fuel reaches the site. A moulding machine draws 22.9 kW at the small end and 104 kW on a QST1800, and the vibration motors, the hydraulic pump station, the cuber and the mixer group add their own share on top of that figure. A grid connection and a diesel set are not equals. One is sized on transformer capacity and cable cross-section, the other on starting margin and stored fuel. Decide the drive after you have measured the load, not before.

What loads sit behind one block machine?

Load is the sum of five groups, and only one of them is the pressing motor. Vibration motors shake the mould at 3,800 to 4,500 times per minute, the hydraulic pump station holds 31.5 MPa, the cuber runs its own drive, the batching and mixing group feeds the mix, and the conveying, curing and packing group runs all day at low load but never stops.

The plate figure is a running sum, not a starting figure: every motor starts above its rated current and the vibration motors start and stop in every cycle. Size the incoming supply on the worst simultaneous start, then check the voltage drop at the far end of the cable run and not at the transformer terminals.

• Installed capacity runs from 22.9 kW on a QT4-15 to 104 kW on a QST1800, with 57.6 kW on a QST1200 and 69.1 kW on a QST1500 between them.
• Vibration force is 280 kN on the QST1800 and 220 kN on the QST1500, which is why the vibration motors dominate the instantaneous load.
• Stacker power is 3.7 kW, and a low-position cuber system carries 34.15 kW at 15 to 18 seconds per layer.
• A twin-shaft mixer adds 25.5 kW to 75 kW, and a pallet feeder cycles every 13 seconds at 3 kW.

What does the starting surge do to the supply?

A direct-on-line start pulls a burst of current that lasts under a second but decides the fuse, the cable and the transformer size. Two effects matter: the voltage at the machine terminals dips during the start, and if the dip is deep enough the contactors drop out and the cycle stops halfway, leaving a half-filled mould under the tamper. The hydraulic pump station peaks when the pressurised stroke begins, so the pump start and the vibration start must not land on the same instant.

Sequencing is the fix and it costs nothing. Start the mixer first and let it reach full speed, bring the vibration group on after that, and hold the hydraulic pump start until the vibration cycle is past its peak. A pallet feeder cycling every 13 seconds and a cuber at 15 to 18 seconds per layer are light but frequent loads, so they belong on their own circuit.

Running on the grid: transformer, cables and protection

A grid connection sizes the transformer and the incoming feeder on the installed capacity of the whole plant, not on the moulding machine alone. A 104 kW machine with its mixer, conveyor and cuber group behind it is a different order of supply than a 44.9 kW machine on a small yard, and the difference is paid at the transformer and in the copper.

Conductor cross-section follows the route length and the starting current, so the same load needs a heavier cable at the far end of a long yard. Earthing and earth-leakage protection belong to the same package: machine frame, control cabinet, curing-area steelwork and conveyor structures go to one common earth, and each feeder trips on a fault current, not on the starting surge.

On a direct drive machine two acceptance points belong on the punch list: vibration frequency holding 3,800 to 4,500 times per minute, and rated pressure holding 31.5 MPa through the press stroke. A machine that reaches the first and sags on the second makes blocks of uneven height, so a supply fault ends up reading as a mechanical one.

Sizing a generator set against installed power

A diesel set is sized with margin above the installed capacity of the plant, and that margin is the starting load, not generosity. The set carries the running load plus the simultaneous start of the largest group while holding frequency and voltage inside the band the PLC tolerates. Motors are inductive, so the plant power factor decides how much of the set rating is available for useful work.

Service is the part that gets underestimated. A set running every shift needs a maintenance rhythm on the shift card, and a standby set needs a load test at intervals so it is known to start under load. Fuel is stored dry and clean: a proper tank, a bund and a filter.

• Add the running load of the machine, its mixer and its conveying group, then confirm the set absorbs the simultaneous start of the vibration motors and the pump.
• The pump holds 31.5 MPa through the press stroke, the heaviest sustained mechanical load in the cycle and the point where the engine feels the load as a drop in speed.
• Fuel storage has to match the hours you run per shift, and the set needs daily checks on fuel level, water separator, oil and battery.
• Spares on site decide availability: fuel filters, an air filter and one injector nozzle set do more for uptime than a larger tank.

How do you mix grid supply with a standby set?

A plant that runs on the grid with a generator behind it needs transfer and interlock, not two cables landing in the same panel. The arrangement is a changeover device with a mechanical and an electrical interlock so grid and generator can never close together, plus a phase-order check and an earth-fault check before the set feeds the plant.

The switching order matters more than the hardware. Stop the feed to the machine, confirm the drive is at zero, bring the set to rated speed and voltage, close the generator breaker, then restart in the normal order with the mixer first and vibration after. Written on a card at the panel, that order keeps a half-emptied mould out of the cycle.

The interlock also protects people. One lockable isolation point per feeder and a visible break before the panel let an electrician work on the 3 kW pallet feeder or the 34.15 kW cuber circuit while the hand is inside the frame.

What we need to propose your electrical configuration

Four items settle the electrical question: the power form at your site, whether a grid connection, a generator set or both, the output you want per shift, the block and paver sizes you intend to sell, and the drive you already own if you are adding a line to an existing plant. Send those and we return a configuration with the transformer and the incoming feeder sized, the circuits and protection listed, and the acceptance points named.

A moulding machine is one block of the load, not the whole of it. The mixer group, the cuber, the pallet feeder and the curing conveyors sit behind it, and the drive decision is made on all of them together. Tell us the power form at your site and the output you are aiming for, and we will size the electrical configuration against your cycle.