Dings Magnetic Group Stationary Electro Overhead Magnets User Manual

Installation and

Maintenance Manual

For

Dings Stationary

Electro Overhead

Magnets

Revised January 19, 2011

Table of Contents

General Information ......................................................................................................... 1

Installation Procedures

Unpacking and Handling.......................................................................................... 2

Magnet Storage ....................................................................................................... 3

Magnet Installation .................................................................................................. 4

Electrical Connections ............................................................................................. 5

Rectifier Over Current Protection ............................................................................. 6

Maintenance .................................................................................................................... 7

Electrical Troubleshooting ............................................................................................... 9

Print of Magnet .............................................................................................................. 13

Print of Rectifier ............................................................................................................. 14

Revised January 19, 2011

General Information

Magnet
Dings Model: Stationary Electro Magnet
Dings Part Number:
Dings Serial Number:
Gallons of Oil in Magnet:
Rectifier
Dings Model:
Dings Part Number:

Warnings:

This Dings magnet emits a powerful magnetic field when energized. The magnet must be
positioned within an inaccessible or guarded area so that no contact can be made with the
magnet while it is in operation.

The surface of the magnet box may reach temperatures of up to 230ºF (110ºC) while
operating. Take care not to touch magnet surface and allow sufficient cooling time before
handling.

Before performing maintenance, the magnet must be de-energized and allowed to cool for at
least 6 hours. Lock out/tag out electrical supplies to prevent unexpected movement or
magnetization during maintenance.

The magnet box is filled with transformer oil to cool the magnet during operation. Inspect oil
level and quality regularly to prevent damage to magnet components.

CAUTION: STRONG MAGNET

Strong magnetic field may have an affect on pacemakers and other electrical devices. Please
contact the device manufacturer for further information.

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Revised January 19, 2011

Unpacking and Handling

Upon receiving, check all packaged material for shortage of parts and possible damage.
Report shortages and damage to the carrier who delivered shipment. The magnet was
shipped fully assembled, ready for operation. Electrical connection is required to a suitable
source of direct current such as a rectifier.

Magnet

This Dings electromagnet was shipped using a pallet or 4” x 6” wooden beams as supports
under the two sides of the magnet. After unloading, the magnet should never be placed
directly on the ground. Rather, wood beams or some other means of support should be placed
beneath the two sides of the magnet box to raise the magnet and belt above the ground.

The magnet should always be moved using the sling assembly provided. Never use a forklift
or other device to lift the magnet from the bottom.

The magnet should be stored indoors prior to installation.

Rectifier

The rectifier is a sensitive piece of electrical equipment. It has been shipped on a separate
pallet to protect it during shipment. Take care not to drop or shake this equipment during
handling.

The rectifier may be left strapped to the pallet while being moved. If it has been removed from
the pallet, make sure it is securely fastened to forklifts or winches for moving.

The rectifier should be stored indoors prior to installation.

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Revised January 19, 2011

Recommended Storage of Overhead Magnets

1) It is essential to keep moisture out of magnet cooling oil.

2) The following precautionary procedures are recommended:

a) Store magnet indoors in a low humidity, even temperature environment if possible.

b) Keep water and any other form of moisture away from the magnet while in storage.

3) This is a procedure for indoor storage only. Outdoor storage is definitely not advised and
will null and void our warranty on the magnet assembly.

4) Rectifiers:
a) It is mandatory that the rectifier be stored indoors away from water and moisture.

b) It is recommended that the rectifier be put in a plastic, tightly sealed cover or bag to

prevent moisture from getting into the rectifier if it’s stored in an unheated building.

c) If possible, rectifier should be stored in an even temperature environment.

Revised January 19, 2011

3

INSTALLATION

An electro overhead magnet is built in 2 types: Inline and Crossbelt. An Inline type is installed
over a conveyor head pulley so that the single turnbuckle parallel to the travel direction of
material falling off the conveyor. The head pulley must be made from non-magnetic material.
A Crossbelt type is installed over a conveyor so that the single turnbuckle side of the magnet
at a right angle to the travel direction of the material on the conveyor.

Magnetic performance may be affected by magnetic material in the field. This includes such
items as I-beams, metal supports, hoppers, or splitters. These and other ferrous objects need
to be kept out of the magnetic zone.

Crossbelt Suspension Inline Suspension

Suspension height is critical to the performance of the magnet. This distance is measured from
the bottom of the magnet face to the surface of the material handling belt.

The magnet should be mounted at the recommended suspension height. IF MAGNET IS TOO
HIGH ABOVE BURDEN, SUFFICIENT MAGNETISM MIGHT NOT REACH INTO THE
BURDEN. TOO MUCH HEIGHT WILL CAUSE A LOSS OF SEPARATION EFFICIENCY. For
best results, crossbelt separators should be centered over the belt and parallel to the slope of
the belt conveyor.

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Revised January 19, 2011

Electrical Connections

Electro Overhead Magnets operate on direct current. The DC connections to the magnet are
made in the terminal box located on one side of the magnet. Polarity is not important. The DC
current is supplied by a rectifier. Do not ground the DC circuit or the magnet will be damaged.

Switching should be done on the input (AC) side of the rectifier. This will avoid excessive
arcing and high inductive voltages which develop when a magnet coil circuit is opened.

Wiring should be in accordance with prevailing local and national electric codes. Wire size
should be based on the nameplate wattage. As magnet coil warms, the wattage will decrease.

Voltage of magnet terminals should be within + 5% of nameplate voltage. If the unit is a self
cleaning magnet, check that the motor wiring is correct for all the power supplied. Make sure
the nuts on the motor wiring tabs are all tight. When operating properly, the magnet will run
hot. The magnet coil is immersed in a special oil which allows it to operate at an extremely
high magnetic intensity. Oil continuously circulates in and around all parts of the coil windings.
This circulation allows even heat distribution for longer coil life. This heat is transferred to the
magnet case for dissipation.

NOTE: Some models have a junction box mounted on the frame. This box is pre-wired to the
terminal box on the magnet body. Connect DC power to the junction box as described
previously.

Connect to a DC Power Source

(Polarity is non essential)
Voltage and watts appear

on magnet nameplate.

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Revised January 19, 2011

RECTIFIER INPUT OVER-CURRENT PROTECTION

All rectifiers contain a transformer. A transformer has all the same component parts as a
motor, and like a motor, exhibit a current inrush when energized. This inrush current is
dependent upon where in the sine wave the transformer was last turned off in relation to where
in the sine wave the transformer is when you energize it. Although transformer current inrush
could run up to 30 to 35 times full load current under a no load condition, it typically will be the
same as a motor at about 6 to 8 times the full load current. For this reason it is important to
use a dual element time delay type fuse, the same type of fuse you would use with a motor. If
using circuit breakers, select a breaker with a time delay, again the same type you would use
with a motor. If the time delay is not sufficient, you may experience “nuisance tripping”, a
condition where the circuit breaker trips when energizing the transformer but when you try it
again, it works fine.

Fuses

Use a dual element time delay fuse or a circuit breaker with a time delay having a rating of 175
percent of the full load current to protect the input side of the rectifier. If 175% of full load
amps does not correspond to a standard fuse size, select the next larger standard fuse size
(but not exceeding 225%).

Circuit Breakers

Use an inverse time circuit breaker with a maximum rating of 250% of the full load current. If
250% of full load amps does not correspond to a standard circuit breaker size, select the next
larger size (but not exceeding 400%).

Caution:

Always follow the latest edition of the National Electric Code and any other applicable codes
for over-current protection of 600-volt class transformers to determine the proper over-current
protection for rectifiers. One special consideration not listed in the above codes is to be careful
of the type of fuse or circuit breaker used to protect the input side of the transformer.

EXAMPLE:

Model 33 Electro Magnet
5 kW, NEMA 12 Rectifier

AC input: 460 VAC/3phase/60 Hz, 6.7 amps

Time Delay Fuses

6.7 amps x 175% = 11.73 amps 11.73 is a non-standard fuse size. The next standard fuse

size is 12 amps. 12 amps is 179% of the full load amps, but is under the 225% maximum limit.
USE A 12 AMP TIME DELAY FUSE.

Circuit Breakers

6.7 amps x 250% = 16.75 amps. 16.75 is a non-standard circuit breaker size. The next

standard circuit breaker size is 20 amps. 20 amps is 299% of full load amps, but under the
400% maximum limit. USE A 20 AMP INVERSE TIME CIRCUIT BREAKER.

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Revised January 19, 2011

ITEM

QUANTITY

BRAND & GRADE

INTERVAL

Magnet

Transformer

Type

Cooling Oil

Gallons

Fina Diekan 410 or

equivalent

Check for volume

every 3 months.

Replace oil every 2-3

years**

MAINTENANCE

LUBRICATION SCHEDULE FOR

OVERHEAD ELECTRO MAGNET

**Note: The oil should be laboratory tested every 12 months for moisture, contaminants, and
dielectric strength.

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Revised January 19, 2011

Periodic inspection and maintenance are required. Check magnet body for oil leaks. Check
pressure relief valve (breather) on top of magnet. It should be free of dirt and obstructions. Oil
seepage from breather is no cause for alarm. It may result from overfilling.

OIL CHANGE OR REFILL
CAUTION: Allow oil to cool completely before servicing.

Oil level should appear at oil level plug hole when magnet is level. Oil should remain clear and
free of contaminants. Sludge in oil will greatly reduce service life. If oil is turbid or cloudy,
replace it. Do not mix new oil with old oil.

USE ONLY THE SPECIFIC COOLING OIL designated on the caution nameplate located on
the side of the magnet. Read this nameplate. The electromagnet contains special high
temperature cooling oil. The use of any different oil can be a fire hazard.

This magnet was originally filled at the Dings factory with the type of oil marked on the caution
nameplate. This oil is safe for use at the high temperature at which this magnet normally
operates. Do not add any amount of any other oil or liquid.

To drain oil, remove drain plug in side of magnet body near bottom. Remove fill plug in top
surface of magnet body. Drain and flush magnet clean using new oil (don’t use old oil or
cleaning solvent).

To refill, replace plug in drain hole. Remove oil level plug in side of magnet body near top.
Place magnet in level position. Fill with oil to oil level plug hole. Reinstall oil level plug and
reinstall oil fill plug. Note - seal plugs with Permatex No. 2 non-hardening. (Do not use
silicone as it is not compatible with the oil and leaks will develop).
GENERAL - Periodically check hex head set screws and bearing bolts for tightness, tighten if
loose.

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Revised January 19, 2011

ELECTRICAL TROUBLESHOOTING

Before starting, first follow this preliminary checklist:

1. Check all fuses and/or circuit breakers. For fuses, use a dual element time delay fuse

with a maximum of 175% of the full load current to protect the input side of the rectifier.
If 175% of full load amps does not correspond to a standard fuse size, select the next
larger standard fuse size (but do not exceed 225%). For circuit breakers, use a n
inverse time circuit breaker with a maximum of 250% of full load current. If 250% does
not correspond to a standard circuit breaker size, select the next larger standard circuit
breaker size (but do not exceed 400% for 100 amps or less).

2. Check all wiring for loose or broken connections.

3. Visually inspect all internal rectifier components.

4. If equipped with a starter, check all overloads (bi-metallic components) to see if any

have tripped. Wait several minutes before resetting.

5. If equipped with a starter, check to see if correct heaters for selected voltage are

installed and that load does not exceed nameplate rating.

6. Do not ground the DC circuit supplying the magnet or damage will occur.

WARNING
The following procedures should be performed by a qualified electrician. Extreme caution
should be used as live electrical equipment will be tested. Before starting the testing
procedure, turn off and lock-out any surrounding equipment that may pose a danger during
testing. If the magnet is of the self-cleaning type, turn off and lock-out the power to the self­cleaning belt motor. The following instructions are for standard 230 VAC or 460 VAC, 3 phase,
60 Hz rectifiers. For special input voltages, consult factory.

STEP 1

Disconnect the DC cable leads to the magnet AT THE RECTIFIER TERMINAL BLOCK inside
the rectifier cabinet. Turn on the power to the rectifier. Measure the AC input voltage to the
rectifier at the terminal block.

1st Reading Phase 1 to Phase 2 Volts:
2nd Reading Phase 2 to Phase 3 Volts:
3rd Reading Phase 3 to Phase 1 Volts:

If all three voltage readings are within the following tolerances, the power supplying the rectifier
is OK. Go to Step 2.

230 VAC + 5% for 230 VAC input rated rectifiers.
460 VAC + 5% for 460 VAC input rated rectifiers.

If one or more of the voltage readings are out of tolerance, the power supplied to the rectifier is
incorrect and must be corrected.

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Revised January 19, 2011

STEP 2

Turn off and lock-out the power to the rectifier. Disconnect the three leads from the
transformer to the diode assembly inside the rectifier cabinet. Turn on the power to the
rectifier. Measure the AC voltage at the output of the transformer inside the rectifier cabinet.

1st Reading Phase 1 to Phase 2 Volts:
2nd Reading Phase 2 to Phase 3 Volts:
3rd Reading Phase 3 to Phase 1 Volts:

If all three voltage readings are 85 VAC + 5% for 115 VDC output rated rectifiers or 170 VAC +
5% for 230 VDC output rated rectifiers, the transformer is OK. Go to Step 3. If one or more of
the voltage readings are out of tolerance, replace the transformer or the entire rectifier.

STEP 3

Turn off and lock-out the power to the rectifier. Reconnect the three leads from the
transformer to the diode assembly at the transformer output lugs inside the rectifier cabinet.
Disconnect the two rectifier output leads to the magnet at the terminal block inside the rectifier
cabinet marked “+” and “-”. Turn on the power to the rectifier. Measure the DC output voltage
of the rectifier at the terminal block inside the rectifier cabinet marked “+” and “-”.

VOLTS:

If the reading is 115 VDC + 5% for 115 VDC output rated rectifiers or 230 VDC + 5% for 230
VDC output rated rectifiers, the rectifier is OK. Go to Step 4. If the voltage reading is out of
tolerance, replace the diode assembly.

STEP 4

Turn off and lock-out the power to the rectifier. Reconnect the two rectifier output leads to the
magnet at the terminal block inside the rectifier cabinet. Turn on the power to the rectifier.
Measure the DC voltage at the magnet box terminals on the magnet, not at the secondary
terminal box on the magnet if so equipped.

VOLTS:

If the reading is 115 VDC + 5% for 115 VDC output rated rectifiers or 230 VDC + 5% for 230
VDC output rated rectifiers, the leads and terminal blocks between the rectifier and the magnet
box terminals are OK. Go to Step 5. If the voltage reading is out of tolerance, replace or
repair the leads between the rectifier and the magnet, as leads may be damaged, loose or
undersized. Use caution not to rotate the studs in the magnet box terminals or the internal
connections may be damaged.

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Revised January 19, 2011

STEP 5

Turn off and lock-out the power to the rectifier. Disconnect the two leads from the rectifier to
the magnet at the magnet box terminals, using caution not to rotate the studs in the feed
through terminals as the internal connections may be damaged. The magnet must be cold for
the following tests. Using the watts and the volts from the nameplate on the magnet, square
the nameplate DC volts (115 VDC or 230 VDC) and divide by the nameplate watts to get the
target ohm reading. Measure the ohms between the two magnet box terminals.

VOLTS:

NOTE: There is no polarity for the magnet terminal posts. Either lead can be connected to
either terminal.

If the ohm reading is within + 10% of the target ohm reading, go to Step 6. If the ohm reading
is out of tolerance or infinity, consult the factory, supplying all of the above readings that were
taken.

STEP 6

Measure the ohm reading between one of the magnet box terminals and the magnet housing,
(The preferred measuring instrument is a megger.)

OHMS:

If the reading is one megohm (1,000,000 ohms) or larger, the magnet is OK. If the megger
ohm reading is out of tolerance, consult the factory, supplying all of the above readings that
were taken.

If it has been determined that the rectifier and the magnetic separator are electrically sound
and the performance of the separator is still in doubt, contact the factory for further assistance.
There are many factors which can affect the ability of a separator to attract metal.

SIGNIFICANCE OF ELECTRICAL READINGS:

Low DC Volts Magnet will be weak

Low Ohms (resistance) Possible shorted turns in coils

High Ohms Possible poor connection or open coil circuit

Low DC Amps Possible poor connection or open coil circuit

High DC Amps Possible shorted turns in coils

Megger Reading Less One or more coils are grounded, poor insulation or
Than 1 Megohm transformer oil is contaminated with water

11

Revised January 19, 2011

Send readings to Dings Company for evaluation and recommendations:

Phone: [phone]

Fax: [phone]

E Mail: [e-mail]

When changing the diode assembly, it is highly recommended that the surge suppressor be
changed as well.

12

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Revised January 19, 2011