10
CHAPTER 2:
Magnet System Design, Installation, and Operation
Model 648 Electromagnet Power Supply
2.3 Magnet
Construction
The magnet consists of two water-cooled coils surrounding adjustable iron poles,
which are fitted into an iron frame. The frame supports the poles and coils, and
improves the magnet’s efficiency. The iron poles are fitted with adjusting
mechanisms so that the air gap width can be set. Lock mechanisms are provided to
hold the poles in place after adjustment is made. The poles faces have pole caps
attached, which provide the desired magnetic focus. The size and shape of the pole
caps are chosen according to the size of the sample being tested and the magnetic
field requirement.
2.4 Connecting
the Magnet
Connecting the magnet to the power supply requires three separate circuits: the
cooling water hoses, the main high current power lines, and the safety switches.
These may include any combination of temperature and flow switches. These
connections are shown in FIGURE 2-2.
2.4.1 Water Hose
Connection
Water-cooling is essential for these magnets. The power dissipated can raise the
temperature of the coils to the point where they will be destroyed. In addition, the
samples being tested may exhibit changes in their magnetic performance with
changes in temperature causing errors in the collected data. Typical water
connection is shown in FIGURE 2-2. The magnets may be supplied with hose barbs or
standard hose fittings. The coils are connected in parallel so that the water
temperature rise is the same for both. Every effort should be made to insure that the
flow rate in both coils is the same. The minimum flow required is usually specified by
the magnet vendor.
Typical magnet water hook-up
Reenforced hose
Optional water filter
Optional water valve
Tee
Optional flow switch
Magnet coil
Hose barb fitting
Hose clamp
Reenforced hose
Hose clamp
Hose barb fitting
Magnet water connection
FIGURE 2-2