Inductive Voltage Spikes - Stanford Research Systems SIM954 Operation And Service Manual

3.3 Inductive Loads

3.3.2 Inductive Voltage Spikes

SIM954 300 MHz Dual Inverting Driver Amplifier
Every (non-saturated) inductor stores an amount of energy equal
2
to E I L 2 in its magnetic field when it is excited by a current I.
If the current loop is suddenly opened (e.g. by opening the circuit
between the curren source and the inductor), this energy will lead to
a rapid buildup of voltage across the inductor due to self induction
and Lenz's rule. This inductive voltage spike can exceed the safe
operating limits of the amplifier's 15 V power supply rails and lead
to destruction of the amplifier.
Inductive loads should only be plugged in or removed from the amplifier
while the power supply is turned o .
If the amplifier is being used as a coil driver, a suitable external
voltage protection device (power zener diode, transient voltage sup-
pressor, etc.) should be used.
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