Placing a resistor after fuses serves several important purposes in electrical circuits:
Current Limiting
Resistors are mainly used to regulate the current flowing through a circuit.
A resistor can as well be used after a fuse to reduce the current flowing in a circuit so as to minimize the amount of current that reaches other delicate components in the circuit.
This is important in order to protect against over current which can arise periodically or during fault conditions.
Voltage Regulation
Resistors can also allow a voltage drop hence making sure that each component gets the right voltage.
This is especially so because different devices function well under different voltage levels.
When a component gets an excessive voltage, it may be destroyed or it may not perform its required function correctly.
Protection against Voltage Spikes
They can be used to ground some of the voltage to safe levels so as not to damage some of the delicate parts of the circuit.
If the fuse is labeled as a result of an overload the resistor can in the same way reduce the effects of any variation in voltage on the resistor and possibly downstream components.
Inrush Current Control
In a circuit, where high inrush currents are anticipated (such as at the start-up of a circuit) resistors can control this inrush current.
This function is especially important in the power supply circuits and chargers because abnormally high voltage may lead to damaging of other elements.
Fusible Resistors
Fusible resistors are the resistors that are also used as fuses, sometimes called fusible resistors.
These components can regulate the current flow in normal circumstances and will burn and break the circuit in case the current passes a certain level; hence, they act as both a protective and a switching device.
Therefore, adding a resistor after fuses improve the protection of circuits since current is limited and the voltage drop is managed, decreases the effects of voltage transients and surge currents.