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Installation and
Maintenance Manual
For
Dings Self-Cleaning
Electro Overhead
Magnets
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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 ............................................................................................. 11
Self Cleaning Belt Replacement Procedure .................................................................. 15
Revised May 19, 2014
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General Information
Magnet
Dings Model:
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 moving
parts while the magnet 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 and affect on pacemakers and other electrical devices. Please
contact the device manufacturer for further information.
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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. If a material deflector was supplied, it was
shipped separately and must be bolted on before operation. Electrical connection is required
to a suitable source of direct current such as a rectifier.
Magnet
This Dings self-cleaning electromagnet was shipped using 4” x 6” wooden beams as supports
under the two sides of the magnet. This is done to protect the belt and the magnet surface
from damage during shipment. 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 four lifting lugs 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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Recommended Storage of Overhead Magnets
1) On a self-cleaner, remove tension from drive belts and conveyor belts.
2) It is essential to keep moisture out of magnet cooling oil.
3) 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.
4) 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.
5) Self-Cleaning Belt:
All belting should be stored in a cool, dry room, free from sunlight, steam pipes, oil, water,
moisture, and corrosive fumes.
6) Reducers:
PERIODICALLY INSPECT STORED OR INACTIVE DRIVES AND SPRAY OR ADD RUST
INHIBITOR EVERY SIX MONTHS, OR MORE OFTEN IF NECESSARY. INDOOR DRY
STORAGE IS RECOMMENDED.
7) Motor:
(One year or less.) Units should be stored indoors, in a clean, dry location. Winding should
be protected from excessive moisture absorption.
8) Bearings:
Rotate bearings every three months.
9) 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 May 19, 2014
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INSTALLATION
A Self-Cleaning electro overhead magnet is built in 2 types: Inline and Crossbelt. An Inline
type is installed over a conveyor head pulley so that the cleaning belt runs parallel to the travel
direction of material falling off the conveyor. The head pulley must be made from nonmagnetic material. A Crossbelt type is installed over a conveyor so that the cleaning belt runs
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. Refer to page 10 for maximum conveyor incline.
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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 self-cleaning 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. After electrical connections have been completed, connect AC power to
the motor thru a motor starter. Be sure line voltage and frequency agree with voltage and
frequency shown on motor nameplate. Check the cleaning belt for correct travel direction.
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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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Page 9
MAINTENANCE
LUBRICATION SCHEDULE FOR
OVERHEAD ELECTRO MAGNET
ITEM QUANTITY BRAND & GRADE INTERVAL
Magnet
Gearmotor
Magnet
Bearings
Transformer
Type Cooling
Oil
**Note: The oil should be laboratory tested every 12 months for moisture, contaminants, and
dielectric strength.
1.8 Quarts
As Needed
See cover
page
Synthetic ISO VG220
Lithium Base NLG 1 Grade
2EP or Equivalent
Fina Diekan 410 or
Equivalent
7
2500 Hours
Monthly
Check for volume every
3 months. Replace oil
every 2-3 years**
Revised May 19, 2014
Page 10
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).
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DRIVE ASSEMBLY
GEARMOTOR - Inspect motor at regular intervals. Keep motor clean and the ventilation
openings clear of dust or other debris. See attached Nord Gear manuals for specific
information.
BEARINGS
LUBRICATION - If conditions are clean, lubricate every 2 to 6 months. If dirty, lubricate every
2 weeks or on a schedule consistent with other equipment in the same environment. Lubricate
with lithium based grease conforming to NLGI Grade 2.
GENERAL - Periodically check hex head set screws and bearing bolts for tightness, tighten if
loose.
SELF-CLEANING BELT
BELT - Periodically inspect for signs of wear and the vulcanized bond of the cleats. If belt
replacement instructions are needed, contact factory.
FASTENERS - Periodically check for wear, especially on the underside. If fastener
replacement instructions are needed, contact factory.
TRACKING - If belt needs to be retracked, refer to belt tracking section below.
ZERO SPEED SWITCH (Optional)
Periodic inspection of the shaft seal is recommended. Bearings of the permanently lubricated
type.
PULLEY/SHAFT ASSEMBLIES
All crown curved pulley compression hubs are properly tightened to the manufacturers’
recommended torque at the factory. Shortly after initial start-up, the hub bolts should be
retightened to the following torques:
Shaft Diameter Torque
1 15/16” 180 in. lbs.
2 3/16” 180 in. lbs.
2 7/16” 180 in. lbs.
2 15/16” 360 in. lbs
Check every 2 to 6 months and retighten as needed.
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BELT TRACKING/TENSION
LOOKING AT THE TAKE-UP END OF THE MAGNET
4 PULLEY DESIGN: 2 PULLEY DESIGN:
TO MOVE BELT LEFT, TO MOVE BELT LEFT,
TIGHTEN THE LEFT TAKE-UP TIGHTEN THE RIGHT TAKE-UP
TO MOVE BELT RIGHT, TO MOVE BELT TO RIGHT,
TIGHTEN THE RIGHT TAKE-UP TIGHTEN THE LEFT TAKE-UP
Belt track and tension should be checked at least every three hours for the first two days of
operation. Once every three days after that.
If the separator is to be installed on an angle (inclined crossbelt) we recommend that the belt
be tracked with the magnet level, then suspend it at its intended position. The maximum
recommended angle of tilt for a crossbelt separator is 20 degrees on a standard design, 15
degrees on a severe duty (CR) design. If the belt is running off towards the lower side, tighten
the take-up on the high side or the side that the belt is traveling away from.
If the belt is still proving difficult to track, check the following:
Are the bearings bolted down tightly to the frame?
Have any moved or shifted?
Are the top two idler pulleys and the drive pulley at right angles to the frame?
Is the magnet self-cleaning frame twisted or bent in any way?
Has the self-cleaning belt been stretched so that one side is longer than the
other?
Have the ends of the belt been cut square to the edge of the belt prior to the
splice being installed?
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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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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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Page 15
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
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Page 16
Send readings to Dings Company for evaluation and recommendations:
Phone: 414-672-7830
Fax: 414-672-5354
E Mail: magnets@dingsco.com
When changing the diode assembly, it is highly recommended that the surge
suppressor be changed as well.
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PROCEDURE TO REPLACE DINGS HINGED SPLICE BELTS ON
OVERHEAD MAGNETIC SEPARATORS
1. After the removal of the original or damaged belt, both take-ups should be taken in as
far as they can go.
2. The new replacement belt should d be laid out flat underneath the separator, cleats
facing down.
3. Draw both ends of the belt together so that the splice hinge pin can be installed.
4. Place the first retaining collar over one end of the hinge pin (leave approximately 3/8”
gap between the collar and the splice end loop).
5. Loosely set all three screws evenly around the hinge pin so all knurled points are in
contact with the hinge pin. Then finish tightening all three screws securely.
6. Place the second retaining collar over the opposite end of the hinge pin (leave
approximately 3/8” gap between the collar and the splice end loop).
7. Loosely set all three screws evenly around the hinge pin so all knurled points are in
contact with the hinge pin. Then finish tightening all three screws securely.
8. The final step is to properly track the new belt and adjust the take-ups as required in
order to keep the belt centered on the pulleys. The proper amount of belt sag must be
maintained in order for the belt to track properly. The proper amount of sag is equal to
2% of the distance between the pulley centers. If the belt is too loose, you may have a
problem keeping the belt centered on the pulleys. If the belt is too tight, it will put
excessive strain on the splice.
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Revised May 19, 2014
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