3111 N. Deer Run Road, Suite 4
Carson City, NV USA 89701
800-808-2434 / 775-884-2434
Fax 775-884-0670 / www.ametherm.com
Circuit Protection Thermistors
Ametherm’s MegaSurge™ Inrush Current Limiter is an economical and space saving way to limit
high inrush current. MegaSurge’s rugged high temperature construction allows safe operation at
high continuous currents. It is specially designed to withstand up to 50 amperes of continuous
current and 900 joules of input energy.
The MegaSurge Inrush Current Limiter is useful in:
➤
AC Motors
➤
Power Supplies
➤
Motor Drives
➤
Audio Amplifiers
➤
Battery Chargers
The MegaSurge Inrush Current Limiter absorbs high amounts of inrush current when electrical
equipment is turned on by offering a high resistance to current and quickly decreasing in
resistance once steady state current begins to flow through the thermistor. In a switching power
supply, the instantaneous surge energy is caused by the large input filter capacitors and
AC input voltage.
During the absorption of energy, the initial high resistance of the thermistor drops within
milliseconds to a negligible resistance in preparation of allowing high levels of steady state
current to flow with a minimal loss of power through the circuit. The MegaSurge Inrush Current
Limiter will absorb up to 900 joules of input energy and carry 50 amperes of steady state current.
➤
Use the maximum allowable inrush
current and Ohm’s Law to determine
the least allowable resistance at
turn on for your application.
➤
Using the formula J=
1
/
2
CV
2
,
determine how much input energy
the thermistor will absorb when the
device is turned on.
➤
Determine the maximum steady state
current that will flow through
the Inrush Current Limiter.
➤
Select the Ametherm Inrush
Current Limiter that will work for
your application.
How does the
MegaSurge
Inrush Current
Limiter work?
Specify the right
MegaSurge
Inrush Current Limiter
for your application.
Ametherm’s new Inrush Current Limiter
provides big protection.
One example of a typical circuit for limiting
inrush current.
Another example of a typical circuit for limiting
inrush current.
➤
Frequency Generators
➤
Plasma Cutting Tools
➤
MRI Machines
➤
Toroidal Transformers up to 4.0KVA
➤
Other equipment that can be improved with
inrush current protection