GMW 3470 User manual

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GMW
USER’S MANUAL
MODEL: 3470
45MM ELECTROMAGNET
Date Sold: _______________
Serial number: ___________
PROPRIETARY
THIS DOCUMENT CONTAINS CONFIDENTIAL INFORMATION
PROPRIETARY TO GMW ASSOCIATES. IT MUST NOT BE REPRODUCED
OR DISCLOSED TO OTHERS OR USED IN ANY WAY EXCECPT FOR THE
INSTALLATION, OPERATION OR MAINTENANCE OF GMW ASSOCIATES
PRODUCTS.
This manual is for the model 3470 electromagnet with serial numbers 206 and above.
For the model 3470 electromagnet with serial numbers 196 to 205 see manual M3470d
For the model 3470 electromagnet with serial numbers 195 and below see manual M3470c
File No: M3470h.407 Revision Date: July, 2009
_________________________________________________________
_
________________________
_
GMW
955 Industrial Road, San Carlos, CA 94070 Tel: [phone] Fax: [phone]
Email: [email protected] Web site: http://www.gmw.com
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TABLE OF CONTENTS
SPECIFICATIONS Section 1
Table 1 Model 3470 General Specifications
Table 2 Model 3470 Electrical and Water Connections
WARNINGS [ Refer to this section before operation of Electromagnet ] Section 2
INSTALLATION Section 3
Unpacking Instructions
Mounting Position
Pole Selection and Installation
Electrical Circuit
Interlocks
Cooling
OPERATION Section 4
General
Calibration
Field Control Operation
MAINTENANCE Section 5
STANDARD OPTIONS Section 6
Probe Holder
CUSTOM OPTIONS Section 7
EXCITATION CURVES Section 8
TEST DATA Section 9
DRAWINGS Section 10
Elmwood 3450 Thermostats
Drawing 11801470-G 3470 Electromagnet, General Assembly (Serial numbers 206 and above)
Drawing 11900010 3470/PT6010 Electromagnet Electrical Assembly
Drawing 13900130 3470/PT6010 Electromagnet Electrical Wiring
Continued
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DRAWINGS
Drawing 11900020 3470/BOP50-8 Electromagnet Electrical Assembly
Drawing 13900140 3470/BOP50-8 Electromagnet Electrical Wiring
Drawing 13900000 3470/BOP50-8 Electromagnet Electrical Wiring
Drawing 11900000 Electromagnet Assembly to Vertical Mount
Drawing 17900300 Electromagnet Vertical Mount Bracket
Drawing 18900040 Electromagnet Tool Kit
Drawing 17801500 Pole Cylindrical/Tapered (40/20mm)
Drawing 17802760 Square Pole Cap (45mm)
Drawing 18900391 Shipping Crate Assembly
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Section 1
SPECIFICATIONS
Table 1. Model 3470 Specifications
Pole Diameter: 45mm (1.75 inch)
Pole Gap: 0 - 75mm (0 to 3 inch)
Standard Pole Face: 40mm (1.57 inch) cylindrical end.
20mm ( 0.79 inch) tapered end.
Coils (series connection)
coil resistance (20°C) 7.3 Ohm
max resistance (hot)* 8.8 Ohm
max power (air) 3.5A/31V (0.11kW)
max power (water) 5A/44V (0.22kW)
Self Inductance
Water Cooling (18°C) 1 liters/m (0.26 US gpm) 0.3 bar (5 psid)
Overtemperature Interlock Elmwood 3450G thermostat part number
3450G 611-1 L50C 89/16 mounted on each coil
and wired in series. Contact rating 120Vac,0.5A.
Closed below 50°C.
Dimensions Drawing 11801470
377mm W x 233mm D x 217mm H
14.8 inch W x 9.2 inch D x 8.6 inch H
Weight 27 kg (60 lb)
*CAUTION - The value of maximum coil resistance given should not be exceeded.
At this resistance the coils are at maximum safe temperature for continuous operation.
1-1
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Section 1
SPECIFICATIONS
Table 2. Model 3470 Electrical and Water Connections
DC Current (refer to Drawing 11801470)
Right hand coil terminal 2 Positive
Left hand coil terminal 1 Negative
Ground
An M4 screw (Item 20 on drawing 11801470) is provided on the magnet yoke to enable the magnet to
be grounded according to local safety regulations. It is normally appropriate to connect the magnet
frame to the power supply ground.
Interlocks (refer to Drawing 11801470).
The temperature interlock wiring connections are made directly onto the temperature thermostats (Item
11 on drawing 11801470).
Water(refer to Drawing 11801470).
Outlet ¼ inch OD Tube
Inlet ¼ inch OD Tube
CAUTION - Ensure that the high current connections are tight. Loose connections may lead to
oxidation and overheating. The field stability may be degraded and the current terminations damaged.
1-2
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Section 2
WARNINGS
REFER TO WARNINGS BELOW BEFORE OPERATING ELECTROMAGNET
1Personnel Safety
In operation the magnet fringing field is in excess of 0.5mT (5G). This can cause malfunctioning
of heart pacemakers and other medical implants. We recommend that the fringing field should be
mapped and warning signs be placed outside the 0.5mT (5G) contour. Entry to this region should
be restricted to qualified personnel.
2Clamp Bolts
Before operation always ensure that both clamp bolts (item 6 on drawing 11801470) are firmly
tightened. Ensure that the poles are arranged so that that pole gap is approximately centered
between the coils.
3Ferromagnetic Objects
During operation the magnet exerts strong magnetic attraction towards ferromagnetic objects in the
near vicinity of its pole gap or coils. Loose objects can be accelerated to sufficient velocity to
cause severe personnel injury or damage to the coils or precision pole faces if struck. Keep
ferromagnetic tools clear!
4Arcing
This magnet stores considerable energy in its field during operation. Do not disconnect any current
lead while under load or the magnetic field energy will be discharged across the interruption
causing hazardous arcing.
5Coil Hot Resistance
Do not exceed the maximum coil hot resistance given in the specifications or coil overheating and
possible damage may occur.
6Interlocks
These should always be connected if the magnet is operated unattended, to avoid the possibility of
coil overheating caused by excessive power dissipation or inadequate cooling.
7Watches, Credit Cards, and Magnetic Disks
Do not move magnetically sensitive items into the close vicinity of the magnet. Even some anti-
magnetic watches can be damaged when placed in close proximity to the pole gaps during
operation. Credit cards, and magnetic disks are affected by magnetic fields as low as 0.5mT (5G).
Depending on the previous operating field and the pole gap, the remanent field in the gap can be in
excess of 50G (5mT) with the magnet power supply off or disconnected.
2-1
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Section 3
INSTALLATION
Caution: This is a heavy system. All movement, lifting and installation of the 3470 Electromagnet
must be under the supervision of an experienced person to prevent the possibility of serious injury or
damage to the Electromagnet and associated equipment.
Unpacking Instructions and Damage Inspection
To unpack the electromagnet please use the following procedure (Refer to Drawing 18800450).
1. First remove all of the "Posidrive Screws" located at the lower edge of all the side panels of the
"Crate Top Cover".
2. Gently rock the "Crate Top Cover" to work it loose from the shipping crate base.
3. Grip the side panels of the Crate Top Cover. Lift "Crate Top Cover" high enough to clear top of
electromagnet, move cover to a clear area.
4. Inspect the magnet to ensure that no damage has occurred to the magnet in shipment. If damage is
evident report the damage in detail to the shipper for claim and simultaneously notify GMW in
case assessment of the damage must be made. If no damage is found proceed with magnet
unpacking and installation.
5. Remove the M8 Hex Head Coach Bolts that secure the magnet to the shipping crate base.
6. The magnet is now prepared for final installation. Follow the appropriate procedure for direct or
base mounting listed below.
Direct Mounting
1. Move magnet to final location and bolt magnet down through the four mounting holes provided in
the magnet angle bracket (refer drawing 11801470)
Pole Selection and Installation (Refer to drawing 11801470).
Using the field uniformity and induction curves determine the most desirable pole; cylindrical or
tapered. In general:
If a uniform field is required use a cylindrical pole end.
If a high field is required use a tapered pole end.
Pole removal (refer to drawing 11801470).
1. Turn off the power supply.
2. Loosen the two pole clamping bolts (item 6 on drawing 11801470).
3. Slide the pole out of the magnet yoke.
3-1
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Section 3
INSTALLATION
Pole fitting (refer to drawing 11801470).
1. Ensure the poles and pole sleeves are clean and free from debris.
2. Reverse the pole removal sequence above.
Electrical Circuit
Never connect or remove cables from the magnet with the power supply connected. The stored energy
in the magnet can cause arcing resulting in severe injury to personnel or equipment damage.
The magnet has two coils which are connected in series. (Refer to drawing 11801470). The power
supply cables should be connected directly to the dc current terminals marked + and -. Recommended
current cable for the 3470 is stranded copper of 1.5 mm² cross section (16 AWG).
Because the magnet stores a significant amount of energy in its magnetic field, special care should be
taken to insure that the current terminations are secure and cannot work loose in operation. Local
heating at the terminations can cause rapid oxidation leading to a high contact resistance and high
power dissipation at the terminals. If left unattended this can cause enough local heating to damage the
terminals and the coils.
The 3470 Interlocks
The Model 3470 has two thermostats, Elmwood 3450G Part Number 3450G611-1 L50C 89/16. They
are located on the outer coil cooling plate and wired in series. The thermostats are normally closed,
opening when the coil cooling plate temperature exceeds 50°C +/3°C.
Cooling
The Model 3470 can be operated to an average coil temperature of 70°C. Assuming an ambient
laboratory temperature of 20°C and a temperature coefficient of resistivity for copper of 0.0039/°C,
the hot resistance of the coil should not exceed 20% more than the ambient temperature "cold"
resistance. The coil thermostat will open when either coil cooling plate temperature exceeds
approximately 50°C . Clean, cool (16°C - 20°C) water at 1 l/min at 0.3 bar (5 psid) should be used to
cool the 3470 magnet.
The cooling copper tubes are electrically isolated from the coils to avoid electrochemical corrosion.
A 50 micron filter should be placed before the input to the magnet to trap particulates and avoid
unreliable operation of the water flow switch interlock if fitted.
For continuous operation of the magnet it may be appropriate to use a recirculating chiller to reduce
water and drainage costs. The chiller capacity will depend on whether cooling is required for the
magnet alone or magnet and power supply. For the Model 3470 Electromagnet alone a suitable chiller
is the Bay Voltex model: RRS-090.
3-2
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Section 3
INSTALLATION
Cooling - continued
For recirculating cooling systems use distilled or deionized water with a biocide to prevent bacterial
growth and corrosion. Do not use corrosion inhibitors in high quality electrical systems since the
water conductivity is increased which can result in increased leakage currents and electrochemical
corrosion.
At currents of approximately 3.50A and below the Model 3470 can be operated safely without water
cooling. However the coil temperature will vary with the power dissipation. This results in
dimensional changes of the magnet yoke and air cooling is not suitable when high field stability is
required.
Freon, oil, ethylene glycol or other cooling mediums can be used. The flow required will be
approximately inversely proportional to their specific heats. An experimental determination of the
flow and pressure required will be necessary.
Avoid cooling the magnet below the dew point of the ambient air. Condensation may cause electrical
shorts and corrosion.
During operation the resistance can be checked using a voltmeter across each coil. The voltage will
rise to a constant value once thermal equilibrium has been reached. If it is desired to save water, the
flow can be reduced until the hot resistance is approached. NOTE: This adjustment must be made
slowly enough to allow for the thermal inertia of the coils.
3-3
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Section 4
OPERATION
General
The magnet operates as a conventional electromagnet.
1. Adjust the poles to the desired gap with the poles approximately symmetrical about the center
magnet line.
2. Adjust the cooling water flow to about 1 liters/min (0.26 USgpm) for the 3470. For operation at
less than maximum power the water flow may be correspondingly reduced. Note that the inlet
water temperature will determine the actual flow rate required. The above specified flow rates
were determined with a water inlet temperature of approximately 18°C.
3. Turn on the power supply and increase the current until the desired field is reached.
Calibration
The induction curves may be used to estimate the field in the air gap to within four or five percent.
More accurate field determination may be obtained by deriving experimentally a calibration curve for
the particular pole and air gap combination being used. Magnetic hysteresis in the yoke and poles can
cause an error of 30 to 70G (3 to 7mT) with an arbitrary application of such a calibration curve. This
effect may be reduced to less than one percent by following a prescribed 'current setting schedule'
designed to make the magnet 'forget' its prior magnetic history. The schedule should of course be used
both in establishing the calibration curve and in its subsequent use. A possible schedule would be:
From zero current, increase to maximum current and reduce again to zero current. Increase again to
maximum current and reduce to the current to give the desired field setting. Approaching the desired
field from a higher setting will typically produce better field uniformity. This is because the field
changes at the pole edges will normally lag the field change at the center thereby helping to
compensate the radial decrease in field.
Greater precision in setting up the calibration curve will be achieved with the use of a digital
teslameter and by making a numerical table. This table used with an interpolation routine will
eliminate the error associated with reading a graph.
In any event, three points need to be remembered:
1. A calibration curve or table is only as good as the precision employed in generating it.
2. The field is defined only at the point it is measured. It will generally be different at a different point
in the air gap. For example, the induction curves refer to the field on the pole axis and at the center of
the air gap (median plane).
4-1
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Section 4
OPERATION
Calibration - continued
3. The field is most directly a function of the current in the magnet coils. Voltage across the coils is
not a good measure of field since the electrical resistance of the coils depends on the temperature
(about 0.4% per degree Celsius).
Field Control Operation
The necessity to use calibration curves can be avoided by using a field controller to sense the
magnetic field and provide a corresponding power supply control signal through the power supply
programming inputs. Contact GMW for suitable instrumentation.
4-2
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Section 5
MAINTENANCE
Periodically check that the poles are clean, properly lubricated and free of grit and dirt, which may
cause binding. Be very careful not to damage the relatively soft pole surface since this may degrade
the magnetic field uniformity in the gap.
Note that the surface treatments used provide good corrosion protection but in order to maintain the
inherent mechanical precision of the magnet, heavy build-up of plating materials is deliberately
avoided. As a result, high humidity or otherwise seriously corrosive atmospheres can cause
corrosion. Periodically apply an appropriate corrosion protection, particularly when the magnet is
stored for an extended period.
Check the cooling water circuit to ensure the water is clean and free of debris and bacterial growth.
Ensure the in-line water filter (if fitted) is clean.
5-1
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Section 6
STANDARD OPTIONS
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Section 7
CUSTOM OPTIONS
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GMW ASSOCIATES
LABORATORY ELECTROMAGNET UNIFORMITY PLOT
Model 3470 Pole Face 20 mm Engr Toomas Rett
Serial No 46 Pole Gap 10 mm Date 20 June, 1995
Hole Dia 4mm
Magnet Current
3.5 Amps
US Army Redstone Arsenal
C7916
Plot Y = 0.0 mm, Z = 0.0 mm
X - Magnet Field X + Magnet Field Magnet Field Average
mm Tesla mm Tesla Tesla
00.78216 00.78214 0.78215 0.000
-1 0.78270 10.78396 0.78333 0.002
-2 0.78520 20.78714 0.78617 0.005
-3 0.78840 30.78972 0.78906 0.009
-4 0.79030 40.79010 0.79020 0.010
-5 0.79022 50.78776 0.78899 0.009
-6 0.78750 60.78324 0.78537 0.004
-7 0.78252 70.77334 0.77793 -0.005
-8 0.77224 80.75658 0.76441 -0.023
-9 0.75588 90.73654 0.74621 -0.046
-10 0.73058 10 0.70608 0.71833 -0.082
00.78214 00.78184 0.78199
Doc no: SC7916U1.057
Uniformity Plot
-0.100
-0.080
-0.060
-0.040
-0.020
0.000
0.020
0.040
012345678910
X AXIS (mm)
Field Deviation
∆B / B
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GMW ASSOCIATES
LABORATORY ELECTROMAGNET UNIFORMITY PLOT
Model 3470 Pole Face 20 mm Engr Toomas Rett
Serial No 46 Pole Gap 10 mm Date 20 June, 1995
Hole Dia 4mm
Magnet Current
3.5 Amps
US Army Redstone Arsenal
C7916
Plot Y = 0.0 mm, Z = 0.0 mm
X - Magnet Field X + Magnet Field Magnet Field Average
mm Tesla mm Tesla Tesla
00.78216 00.78214 0.78215 0.000
-1 0.78270 10.78396 0.78333 0.002
-2 0.78520 20.78714 0.78617 0.005
-3 0.78840 30.78972 0.78906 0.009
-4 0.79030 40.79010 0.79020 0.010
-5 0.79022 50.78776 0.78899 0.009
-6 0.78750 60.78324 0.78537 0.004
-7 0.78252 70.77334 0.77793 -0.005
-8 0.77224 80.75658 0.76441 -0.023
-9 0.75588 90.73654 0.74621 -0.046
-10 0.73058 10 0.70608 0.71833 -0.082
00.78214 00.78184 0.78199
Doc no: SC7916U2.057
Field Vs. Position
0.66000
0.68000
0.70000
0.72000
0.74000
0.76000
0.78000
0.80000
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
X Position (mm)
Field in Tesla
Hole
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