Contents
What limits the current in a DC motor?
DC motor starters. The counter-emf aids the armature resistance to limit the current through the armature. When power is first applied to a motor, the armature does not rotate. At that instant the counter-emf is zero and the only factor limiting the armature current is the armature resistance and inductance.
Does a DC motor have inrush current?
DC motor inrush is the maximum, instantaneous input current drawn by the DC motor when first turned on and it is important to know how to limit the inrush current to prevent possible damage to the motor.
How does current limiting work on a DC motor?
When motor power comes on to close the valve the RC circuit begins to climb until it surpasses the reference voltage. When it times out it can shut off motor current. With a little thought you can further expand the circuit so that it holds itself off until you manually reset the system so as to open the valve electronically as well.
What makes a DC motor different from other types of motor?
The starting of DC motor is somewhat different from the starting of all other types of electrical motors. This difference is credited to the fact that a DC motor unlike other types of motor has a very high starting current that has the potential of damaging the internal circuit of the DC motor if not restricted to some limited value.
What is the resistance of a DC motor?
To prevent such an incidence from occurring several starting methods of DC motor has been adopted. The main principal of this being the addition of external electrical resistance R ext to the armature winding, so as to increase the effective resistance to R a + R ext, thus limiting the armature current to…
How often does a DC motor need to be operated?
As the valve reaches the end of its travel the motor will load and begin to stall. This valve will be operated at most once a day. The motor/gearbox does not have enough torque to cause damage to the valve, just enough to close it tightly.