Block Machine Voltage for Middle East Countries

Block machine voltage for middle east countries belongs on the first line of the specification, not in the installation notes, because the machine is built around a supply rather than adapted to one later. Our block machines and our packaging equipment leave the works wired for 380 V three-phase at 50 Hz with a protective earth. The baler datasheet states it plainly: 380 V / 3 ph / 50 Hz + PE, at 2 kW.

The mistake we see most often is a buyer who confirms the voltage of the town supply instead of the voltage on his own transformer terminals, and never checks what will still be there when the press pulls its peak. All three can differ by enough to change the order. Here is what each gap does to the machine, and what to send us so nothing is rebuilt on site.

The supply our machines are built around

Two reference points come from our data sheets. The translation baler is listed at 380 V / 3 ph / 50 Hz + PE with 2 kW installed. The top rotary baler is listed at AC 380 V / 50 Hz, 3.1 kW, about 5 kVA overall, on 380 V 3P + N + PE, with a DC 24 V control circuit. The block machines follow the same convention.

That convention is not a preference. It fixes four things at once: the winding of every motor on the machine, the coil voltage of every contactor, the primary tap of the control transformer, and the setting of every overload relay. Change the supply and one of those four is wrong, and which one fails first depends on how far your site sits from 380 V.

What a 415 V or 440 V site does to a 380 V panel

A 415 V or 440 V supply rarely burns a 380 V machine on the first day. It runs the panel slightly hot and slightly early, and the insulation sees a higher peak voltage every cycle. Motor current drops a little at the same load, so an overload relay set for 380 V no longer protects the winding the way it was set to.

The control side shows the arithmetic plainly. With the control transformer primary tapped at 380 V and the site at 440 V, every secondary voltage rises by the same ratio, 440 divided by 380, about 16 percent. A rail built to sit at 24 V DC now sits near 28 V, and the PLC input card, the sensors and the touch screen were not bought for that.

There are two ways out. A step-down transformer ahead of the panel holds the machine at 380 V and keeps the warranty intact, at the cost of a transformer, its losses and its footprint. Or the machine is re-rated at the works with 440 V motor windings, 440 V contactor coils and a transformer tapped for 440 V. The second is cheaper in steel and longer in lead time.

What does 60 Hz do to the motor and the pump?

Frequency is the harder half. Shaft speed follows supply frequency, so 60 Hz against 50 Hz is a rise of one fifth, 20 percent. A four-pole motor that turns at 1,500 rpm on 50 Hz turns at 1,800 rpm on 60 Hz. The winding also loses torque margin, since 380 V over 60 Hz is fewer volts per hertz.

The hydraulic pump is positive displacement, so flow follows shaft speed: twenty percent more speed is twenty percent more oil per minute. The press closes faster than the cycle was timed for, the pressure ramp reaches the 31.5 MPa setting sooner, and the relief valve works harder. Cycle time shortens against the quoted 15 to 25 seconds, which looks like free output until the mould cannot vent air that fast and the block leaves with chipped corners.

The vibration side follows the same physics. Our block machines run at 3,800 to 4,500 vibrations per minute, and that figure is set by the vibrator motor speed. On 60 Hz those motors turn 20 percent faster, so the eccentric weights must be re-set or the machine runs outside its designed band and starts loosening its own mould bolts. A 60 Hz machine runs on different eccentric settings, not on another socket.

Sizing the generator from 34.4 kW to 104 kW

Where a plant runs on its own set, the generator is sized from installed capacity, not average draw. Across our block machines the installed capacity runs from 34.4 kW to 104 kW, with 44.9 kW, 48.9 kW, 57.6 kW and 69.1 kW in between, and the stacker adds 3.0 kW or 3.7 kW by model. The baler adds 2 kW. These are running figures.

Two corrections matter. The first is kVA against kW. The top rotary baler draws 3.1 kW but is rated about 5 kVA overall, and the kVA figure is what a generator has to carry. The second is starting current, several times running current for the seconds a motor takes to come up. A set sized exactly at installed kW dips on every start.

The cost is specific. The cycle aborts mid press, the block in the mould is scrap, and the pallet has to be cleared by hand before the machine will start again. Headroom on the generator, a steady governor and an automatic voltage regulator cost less than a week of scrap.

Why does the machine at the end of the feeder trip first?

Voltage drop along a feeder is current times length times conductor resistance. At 104 kW on a 380 V three-phase feeder the running current is about 158 A, which is 104,000 divided by the square root of three times 380, and that current passes through every metre of cable from the transformer.

The machine at the far end therefore sees less voltage than the one beside the panel. Its motors draw more current for the same torque, its overload relays sit nearer their trip point, and on a start it dips furthest. When a plant calls to say one machine trips while the rest are fine, the first question is the distance to the transformer.

Phase rotation, neutral and earth close the list. A three-phase motor runs backwards on two swapped phases, and on a block machine the pump then turns the wrong way, builds no pressure and can damage itself in seconds, so rotation is checked with the motor uncoupled before the first start. The neutral is not optional on equipment specified as 3P + N + PE, because the control circuit and the DC supply come off a single-phase tap. The earth is the only path that matters when a winding fails.

Which five numbers should reach us before production starts?

Send these five and the machine is built for your site. Leave them until installation and the fix is a transformer, a re-wind or a new panel, each of which costs more after the machine has shipped than before it was built.

• Site voltage, measured at the terminals where the machine will be connected, not the nominal figure on the utility bill.
• Supply frequency, 50 Hz or 60 Hz, confirmed from the utility or from the generator nameplate.
• Number of phases, and whether a neutral is available at the connection point.
• Generator kVA, and the largest single motor it has to start, if the plant runs on its own set.
• Distance in metres from the transformer or the generator to the machine position, measured along the cable route.