A scrap magnet turns a Kobelco into a material handler. It lifts plate, rebar, turnings and shredded feed faster than any grapple, and it does it with one electromagnetic coil instead of pins, cylinders and a rotation motor. The price of that simplicity is electrical: a coil drawing several kilowatts from a 24-volt system pulls well over a hundred amperes continuously, switched on and off hundreds of times a shift, through cables that flex along the boom every cycle. Guangzhou Shenyue Machinery Technology Co., Ltd. quotes the parts behind these installations every week, and most breakdowns trace to the supply side, not to the magnet itself.
What a magnet asks of the machine
An electromagnet is a large resistive load with real inductance behind it. The coil fixes the current; the machine's job is to deliver that current without unacceptable voltage drop. Every volt lost in the cable is a volt not across the coil, and lifting force falls with it. A four-kilowatt coil on a 24-volt system draws roughly 170 amperes the entire time the magnet is energized, so wiring, connectors and switching must be sized for that as continuous duty, not as a brief starting load. The battery helps on pickup, but it cannot carry the shift: a rig that lifts strongly for an hour and then fades has an undersized charging side.
Generator, alternators or battery bank
Three supply arrangements are used. A dedicated engine-driven generator, frame mounted and sized for the magnet alone. A pair of high-output alternators charging a dedicated battery bank that buffers the load, the common retrofit. Or, on smaller magnets, one heavy alternator with the standard batteries doing most of the work.
The alternator families we hold most often for this work are A3TN5188RQ / VAME017614 and VA32G6800100, quoted with the machine model and serial because the same engine family changed ratings between builds. Each line is marked genuine, OEM or aftermarket on the quotation.
The contactor and the arc it must survive
Somebody has to break 170 amperes of inductive current every time the operator drops the load, and that is the contactor's whole life. Interrupting an inductive load draws an arc, and an underrated contactor fails in one of two directions: the contacts weld closed and the magnet will not drop, or they burn away and the magnet will not lift. A proper unit is rated for the current with arc suppression built in, and it is a wear item.
The control side is light: a cab switch, a latching arrangement so the load cannot be energized accidentally, and a fuse sized to protect the feed. The fuse box relay group, such as YN24S00012P2, is the class we quote for that side.
Cabling: where magnet installations actually fail
The cable run is the failure point of almost every magnet rig. It carries full current at low voltage, so it must be generously sized, of welding-grade flexible construction, and routed with a slack loop at the stick head so full stick travel never loads the connector. Every clamp point is a chafe point, and plate edges cut insulation in a scrap yard.
Inspect the insulation with a megger on a schedule, not after an incident. A ground fault in a magnet cable drops the load without warning, which is why nobody walks or works under a suspended magnet, ever. Replacement cable sets and boom-route connectors are commonly quoted items, because magnet hardware varies by maker and rating, and the nameplate on the coil is the authority.
Duty cycle and operating practice
A magnet coil heats as it works, and a hot coil lifts less. Letting the coil cool between heavy cycles and keeping the terminal box sealed are the two habits that stretch coil and cable life. Pick, do not rake: dragging the magnet through scrap side-loads the cable connector at the bracket and shuffles the coil inside its case.
What to send for a quote
Send the machine model and serial, the magnet plate, the supply arrangement you have or want, and photographs of the cable route. We supply from three thousand part types on the shelf with over one hundred thousand part numbers available to order through original supply channels, every line marked genuine, OEM or aftermarket. Alternators, relays and chassis cable harnesses such as LC13E01186P1 sit in the electrical parts range, and the wiring harness and fuse guide covers connector identification for the control side. Buyers running mixed-brand scrap fleets usually source the non-Kobelco electrical items through our export brand partner site corbayparts.com, and machine-level data is published at kobelco.co.jp. The demolition and scrap site guide covers the structural side of the same work, and quotes start at the contact page.
Guangzhou Shenyue Machinery Technology Co., Ltd. is an independent supplier of Kobelco parts, not affiliated with Kobelco Construction Machinery Co., Ltd. Genuine parts are supplied through original channels alongside quality OEM and aftermarket alternatives at distributor-level prices.
Frequently Asked Questions
Can I run a scrap magnet from the standard Kobelco alternator?
Only a small one, briefly. A four-kilowatt coil draws about 170 amperes continuously, far beyond a standard single alternator, so the battery carries the difference until it discharges and lifting force fades. Real installations use a dedicated generator or a pair of high-output alternators with a battery bank.
Why does my magnet drop loads without warning?
Almost always a ground fault or a break in the cable near the stick head, where the cable flexes every cycle and takes cuts from plate edges. Megger the cable before blaming the magnet, and remember that a fault of this kind drops the load instantly, so nobody works under a suspended magnet.
What makes a magnet weaker through the day?
Coil heating. Resistance rises with temperature, current falls, and lifting force drops with it. It is normal within the maker's duty cycle; if the fade is fast, check that the supply is holding voltage under load rather than discharging through a tired battery bank.
Do you supply magnet contactors and cable sets?
Yes, commonly quoted items. Because magnet hardware varies by maker and coil rating, the plate numbers and the printed cable size are the authority. Guangzhou Shenyue Machinery Technology Co., Ltd. quotes the contactor, cable and connectors alongside the alternator side, each marked genuine, OEM or aftermarket.