Can I get some help to clear up the difference in a power-limited circuit and a non power-limited circuit? I understand that a transformer is limited by the fact that it will only supply a limited amount of power by it's design. But where do you draw the line at unlimited? I understand that limited and unlimited wires need to be separated but what is what? 120 vac I understand to be unlimited but isn't it limited by a circuit breaker?
I have this definition from the National Fire Academy but am not clear on what it means:
https://www.usfa.fema.gov/downloads/pdf/coffee-break/cb-2007-12.pdf
Power-Limited Fire Alarm (PLFA) Circuits.
A power-limited fire alarm
circuit is one that is inherently unable to exceed maximum voltages, or
is equipped with a power-limiting source (transformer or battery) and a
circuit breaker. Generally, these operate in the 24-volt direct current range,
although they may employ higher voltages.
Nonpower-Limited Fire Alarm (NPLFA) Circuits.
Nonpower-limited fire
alarm circuits cannot operate at more than 600 volts, and there is no other
power or current limitation for these systems. Usually these are used in 120-
volt alternating current (AC) systems which have been rendered generally
obsolete by the advent of low-voltage, direct current (DC) systems.
Any help?
I have this definition from the National Fire Academy but am not clear on what it means:
https://www.usfa.fema.gov/downloads/pdf/coffee-break/cb-2007-12.pdf
Power-Limited Fire Alarm (PLFA) Circuits.
A power-limited fire alarm
circuit is one that is inherently unable to exceed maximum voltages, or
is equipped with a power-limiting source (transformer or battery) and a
circuit breaker. Generally, these operate in the 24-volt direct current range,
although they may employ higher voltages.
Nonpower-Limited Fire Alarm (NPLFA) Circuits.
Nonpower-limited fire
alarm circuits cannot operate at more than 600 volts, and there is no other
power or current limitation for these systems. Usually these are used in 120-
volt alternating current (AC) systems which have been rendered generally
obsolete by the advent of low-voltage, direct current (DC) systems.
Any help?