HELMHOLTZ COIL INSTALLATION AND CALIBRATION
3.
Precautions of use
Some precautions are required when using the equipment. Certain elements of the system are heavy
and should not be handled by one person alone. Coils and PA1 should always be carried by multiple
people. In the case of the coils, they should not be lifted by the coils themselves but instead using the
supporting structures (upright pillars in the case of the HC1/9/16). When assembling the HC2, multiple
people will be required to hold the coils in place and fit the supporting brackets at the same time.
The PA1 can generate large currents. Under no circumstances should the PA1 be opened when plugged
into mains power. Any maintenance operation in the clearance of air intake filters should be done with
the PA1 off, and the mains supply disconnected. Mains connection should be suitably grounded.
Connection of the coils to the PA1 should be secure, ensuring that the connector is pushed in and rotated
until a click can be heard, and the connector cannot be pulled out without depressing the metal tab and
rotating the connector.
The magnetic field generated by the coils, whilst not very high, may interfere with medical devices.
Any equipment susceptible to magnetic field should be kept away from the coils. Refer to the specific
coil’s operation manual to see field amplitude at given distances
.
4.
Assembly and Orientation
The HC1, HC9 and HC16 come pre-assembled. Only the HC2 requires assembly on site (in addition to
the 2m Ferronato coil). Assembly instructions for the HC2 can be found in the HC2 Operation Manual.
The coil’s orientation should be carefully considered. As part of the original setting up
of the coil
consists of zeroing the coils for the local environment, the orientation of the coil should be chosen to
reduce the amount of current used to cancel out the field. The larger coils will typically have a lower field
to current ratio, and the smallest will have a higher one.
It is therefore recommended to sit the coil so that, within the mechanical setup of the coils, the
smallest available coil generates a field in the North/South direction (approximately or whichever is the
direction of maximum field in the horizontal plane). This can be determined at the time of the site survey,
or at the time of installation. Positioning the coils in any other directions will lead to a higher current
requirement to cancel out the Earth’s field. Whilst not an is
sue in most cases, it may become a limiting
factor if attempting to generate fields at the limit of the coil’s performance (or if the field/current ratio of
the coils are low).
5.
Setup
Once a suitable site has been found, the system can be connected together. First connect the coils to
the PA1. Then connect the PA1 to the CU1 (two connections between these two elements takes place,
between the Current Control Input/Output and the Current Monitor Input/Output). If using the CU2, this