Section 3
INSTALLATION
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 11910040). The power supply
cables should be connected directly to the dc current terminals marked + and -. Recommended current
cable for the 5451 is stranded copper of 16mm² cross section (4 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 5451 Interlocks
The Model 5451 has six thermostats, Elmwood 3450G Part Number 3450G611-1 L50C 89/16. They are
located on the coil cooling plates and wired in series. User connections are made directly to the thermostat
terminals.
Cooling
The Model 5451 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
thermal thermostats will open when any coil cooling plate temperature exceeds approximately 50°C . Clean,
cool (16°C -20°C) water at 2 l/min and 1 bar (15 psid) should be used to cool the 5451 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.
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 5451 Electromagnet alone a suitable chiller is the Bay Voltex
Model: MC-50 Chiller. For the 5451 and 858-70A/30V Power Supply the required Chiller is Bay Voltex
Model: MC-100. 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 25A and below the Model 5451 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 and air cooling is not suitable when high field stability is required.
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