Buying an electric motor of 90 kW and above is a very different process from picking a product from a catalogue and waiting for the courier. Motors in the 250, 280, 315 and 355 frame classes - with weights ranging from half a tonne to two tonnes - require special transport, crane-assisted unloading, a reinforced-concrete foundation and a planned commissioning operation. In this power class, a single poorly planned step gives rise to on-site delays that cost more than the motor itself. As HEM Motor, we have been manufacturing electric motors in Turkiye since 1979, and as one of the few suppliers able to deliver large-frame motors from stock, in this article we will help you plan the purchase of a 90 kW-plus motor step by step, from the moment of ordering to the first loaded run.

High-power electric motor above 90 kW ready for dispatch in the factory stock area

The Stock Reality in the 250-355 Frame Class: Why Can't Every Supplier Keep These Motors on the Shelf?

For small and medium-power motors (0.37-75 kW) you will find dozens of sellers on the market; however, once you go above 90 kW the picture changes. In this class, which starts at the 250M frame and extends to the 355L frame, each motor carries a high stock cost, occupies a large storage volume, and demand is sparser than for small motors. For this reason many sellers import these frames from abroad to order, and the lead time can stretch to 8-16 weeks.

Which Powers Correspond to Which Frame?

For 4-pole (1500 rpm) motors the rough match is as follows: the 280 frame for 90-110 kW, the 315 frame for 132-160 kW, the 315L-355 frame for 200-250 kW, and the 355 frame for 250-355 kW. While the same power may fit one frame smaller on 2-pole (3000 rpm) motors, on 6- and 8-pole low-speed motors you have to go one frame larger for the same power. When making your purchasing plan, take into account not only kW but also how the speed changes the frame; because the transport and foundation of a 355-frame motor demand entirely different preparation compared with a 280 frame.

The Impact of Stock Delivery on the Project

When you are setting up a cement mill, a stone-crushing line or a large pump station, the motor is usually on the critical path: the mechanical assembly finishes but the line does not turn until the motor arrives. The difference between a 132 kW 4-pole motor waiting in stock and an imported motor with a 12-week lead time is the opening date of the project itself. Large frames regularly feature in HEM Motor's three-phase electric motors production programme, and thanks to the in-country stock structure many power-speed combinations can be dispatched without waiting. Confirming which frames are ready before ordering, with a single phone call, forms the basis of your entire lead-time plan.

The Lead-Time Plan: The Correct Sequence from Order to Shipment

In high-power motor supply, a sound lead-time plan is built backwards from three dates: the commissioning date, the mechanical-assembly date and the date the motor enters the site. At least one week before the motor enters the site, the foundation concrete must have been poured and cured, the crane or forklift must be reserved for that day, and the electrical-panel side must be ready for cabling. Conveying the correct information in full to your supplier at the quotation stage is the first link in this chain; you can find the details of which information should be given in our article on the information to provide when requesting an electric motor quote, so we will not repeat it here. For large motors, let us additionally stress only this: the suitability of the delivery address for crane access and the load-bearing capacity of the ground at the unloading point are matters that should be discussed at the quotation stage.

Transport: Weight, Vehicle Selection and Insurance

A 355-frame motor, with its weight approaching 2,000 kg, cannot enter the standard courier network. In this class, transport is carried out by securing the motor on a pallet, supporting it with steel or wooden blocks, and carrying it in a closed-box or tarpaulin-covered vehicle.

Vehicle and Route Planning

What is decisive in vehicle selection is not only the weight of the motor but the unloading capability at the destination. A crane-mounted (hiab) truck is the most practical solution for most deliveries in the 90-200 kW band, because it removes the need to organise a separate crane on site. For larger frames, shipment is made with a standard truck and unloading is carried out with a mobile crane on site. On the route side, check in advance the door widths within the factory site, the heights of bridges and underpasses, and the approach distance of the vehicle to the unloading point; a vehicle being unable to approach within 10 metres of the unloading point means moving up a crane-capacity class, which multiplies the cost.

Why Should Transport Insurance Not Be a Matter for Negotiation?

The most common transport damage on high-power motors is impacts to the shaft end, crushing of the fan cowl, and frame cracks caused by tipping over. Some of this damage is not visible from the outside; a micro-deformation in the bearing housing only reveals itself when the motor heats up under load. For this reason, transport insurance covering the full shipment value should be a standard, not an option, in a large-motor purchase. Always ask whether the insurance policy includes the unloading operation in addition to the invoice value of the motor; some policies are valid while on the vehicle but lapse the moment it is taken onto the crane sling.

Checks to Make on Receipt

When the vehicle arrives on site, photograph the motor before unloading, check the tip-over and shock labels on the packaging, and note any visible damage on the delivery note. Turn the shaft end by hand: if you feel catching, a rubbing noise or stiffness throughout the rotation, call your supplier before commissioning the motor. This five-minute check eliminates all the liability disputes that could arise later.

A large-frame electric motor being lowered onto the foundation base with a crane

Unloading on Site: Crane and Forklift Operation

Motors in the 90-160 kW range (approximately 600-1,100 kg) can be unloaded with a suitable-capacity forklift; however, the forks must never touch the motor frame or shaft directly, and the motor should be carried while on the pallet. Above 200 kW, a mobile crane is in practice the only safe option.

The golden rule in crane lifting is this: the motor is lifted only from the lifting eyebolts on the frame. Check that the eyebolts are fully seated in the frame and that the sling takes the load at the angle specified by the manufacturer, not at a right angle to the eyebolt axis. On single-eyebolt motors, an unbalanced lift can cause a crack at the base of the eyebolt. The terminal box, fan cowl and shaft end must never be used as a lifting or resting point. During unloading, bring the motor towards the foundation centimetre by centimetre; a released motor striking the foundation leaves marks on the bearing balls that emerge under load.

Foundation and Base Preparation: The Invisible Detail That Determines the Motor's Life

A significant part of vibration problems on high-power motors stems not from the motor but from the foundation. For a sound installation, the following three conditions are sought:

1. Mass and rigidity: The reinforced-concrete foundation should be of sufficient solid weight relative to the total of the motor seated on it and the driven equipment, and should be poured separately from the floor concrete so as not to create a vibration bridge.

2. Flatness: The surfaces on which the motor feet seat must be machined in the same plane. If one of the feet is left unsupported, the frame warps when the bolt is tightened; this is called soft foot and it seriously shortens bearing life on large frames. If there is a gap, it is closed with calibrated shims.

3. Anchoring: The anchor bolts should be placed with a template before the concrete is poured, or set afterwards with chemical anchors. The bolt diameter and embedment depth are selected according to the motor weight and the starting torque; on 315-355 frame motors, leave this calculation to the design engineer.

Coupling alignment on large motors must be done with a dial gauge or a laser alignment device. Alignment done by eye and with a ruler is outside the acceptable tolerance above 90 kW; misalignment wears out the bearings of both the motor and the driven machine together.

Phased Commissioning: Split the First Run into Three Stages

Stage 1 - Electrical preparation: Before commissioning, measure the winding insulation resistance with a megger and record the value; this measurement is the first page of the motor's life logbook. If starting will be done with star-delta, a soft starter or a drive, verify the compatibility of the parameters with the motor nameplate values.

Stage 2 - No-load running: Run the motor uncoupled (separated from the load). Verify the direction of rotation, measure the no-load current across the three phases and check for imbalance, and monitor sound and temperature from the bearing zones. A 30-60 minute no-load run reveals any hidden transport-induced damage.

Stage 3 - Phased loading under load: Connect the coupling and, if possible, increase the load gradually. In the first hours, watch the bearing temperatures settle; if the temperature rises and stabilises at a value it is normal, if it climbs continuously, stop and check the alignment. Taking a vibration measurement within the first 48 hours and keeping it as a reference value forms the basis of the predictive maintenance of the years to come.

From Site Entry to Assembly: Temporary Storage and On-Site Handling

A large motor often arrives on site before the foundation is ready, or the assembly is planned for a few days later. If this waiting period is not managed correctly, it becomes the source of the first damage the motor suffers. Keep the motor on its packaging, on a flat and dry floor, covered over; if it will wait in the open, protection that prevents rainwater from entering the terminal box and the fan cowl is essential. During handling within the site, never drag the motor with a chain or rope; every relocation must be made on a pallet, with a forklift or pallet truck. For waits exceeding a week, turning the shaft by hand every few days prevents the bearings from remaining loaded at the same contact point. This simple discipline forestalls the "the motor came out of storage but it is making a noise" surprise on commissioning day.

Choosing the Starting Method: At High Power, Consider the Grid Too

On motors above 90 kW, direct-on-line starting means drawing 6-8 times the nominal current from the grid; this both strains the transformer and cable cross-sections and creates a voltage dip in other equipment on the same busbar. In this power class, star-delta is the minimum solution, a soft starter is the comfortable solution, and a frequency drive is the correct solution in applications requiring both soft starting and speed control. The critical point in terms of purchasing is this: the starting method must be settled together with the motor order; because for star-delta starting the motor needs a 6-terminal connection, and a motor that will run with a drive needs a suitable insulation structure. Discuss the starting torque requirement of the driven load (the difference between machines that start loaded, such as crushers, and fans that start unloaded) with your supplier at the order stage; the wrong choice of starting method makes even the right motor appear to fail on site.

Commissioning-Day Checklist

For the first run day of the large motor, all of the following items should be ready on site: the foundation concrete cured and the anchors torqued; the coupling alignment report taken; the insulation resistance measured and recorded; the protection-relay settings set according to the motor nameplate; the starting equipment (star-delta timing, soft-starter ramp or drive parameters) configured; the emergency stop tested; the device for bearing temperature and vibration measurement ready. If you share this list with your supplier at the order stage, support for any missing items can be planned together with the shipment. The first measurements taken during commissioning (no-load current, loaded current, bearing temperatures, vibration values) are the first page of the motor's health record; enter these values on the position card, because a deviation that emerges years later can only be caught early by comparing it against the first-day reference.

If You Are Buying More Than One Large Motor

If you are setting up a new plant and buying more than one high-power motor in the same project, consolidating the shipments into a single plan reduces both the transport operation and the crane cost considerably. We addressed the strategies to follow in multi-item purchases in our article on reducing costs in wholesale electric motor purchasing. In addition, at high powers the effect of the energy-efficiency class on operating expense is many times greater than for small motors; for this reason, above 90 kW we strongly recommend that you evaluate the high-efficiency electric motors product group.

Frequently Asked Questions

What is the typical delivery time for motors above 90 kW?

For frame-speed combinations held in stock, shipment within the same day or a few days is possible. For out-of-stock special configurations (special shaft, different voltage, special paint, etc.) the time lengthens depending on the production plan. For motors arriving through the import channel, an 8-16 week lead time is usual. For the motors on your project's critical path, obtaining stock confirmation before ordering is the safest route; HEM Motor shares large-frame stock status instantly by phone.

Who organises the crane to unload the motor?

In standard practice, unloading from the vehicle is the buyer's responsibility; however, this is a matter that should be clarified in the contract. At the order stage, define the delivery method in writing (delivery on the vehicle, or including lowering onto the foundation) and ask whether the transport insurance covers the moment of unloading. On deliveries requiring a crane, matching the vehicle's arrival time with the crane reservation to the same half-day prevents waiting charges.

Can I run the motor on a temporary chassis without a foundation?

No-load running can be done on a rigid steel chassis for short-term testing; however, for continuous operation under load a foundation of suitable mass with assured flatness is essential. On large motors run loaded on a temporary chassis, vibration-induced bearing and shaft damage may be assessed as outside the warranty scope. Waiting a few days for the foundation to cure is always cheaper than chasing a fault that will take months.

Get a Quote

For your electric motor needs above 90 kW, convey the frame, speed and mounting type; let us settle the stock status, lead time and transport plan the same day. HEM Motor, a manufacturer since 1979, is with you on high-power motors with stock delivery and commissioning support. You can reach us by telephone at +90 (532) 345 49 86 or through our contact us page.