New Holland CX720 Repair Manual page 189

The feeder angle sensor (1) and optional header stubble height potentiometers (not shown) require further adjustment
to provide proper HHC operation as follows:
A. Enter the InfoView™ monitor Diagnostic screen for the potentiometer.
B. Adjust the potentiometer so that the indicated voltage on the screen stays within a range of 2.5 - 7.5 V throughout
the normal operating motion of the potentiometer. In practice, this is most easily accomplished by raising the
feeder fully, and adjust the potentiometers so that the diagnostic screen indicates less than 7.5 V.
ELECTROMAGNETIC DEVICES
In general, they use the magnetic field created by flowing current to move metal parts within the components.
RELAYS
The relay is an electromagnetic switch that uses a small amount of current to switch a larger amount on and off.
When the operator closes a switch, current flows through the relay's control circuit. In this circuit there are windings
surrounding an iron core which is fixed in place.
Current turns the iron core into an electromagnet. The core then attracts an arm which has a contact point on it. When
the point on the arm contacts the stationary point, current flows through the power circuit.
Relays are basically electrically operated switches. They are used to switch a circuit on/off in similar way to a manual
switch.
Two circuits are connected to the relay:
A work circuit, which is switched on/off by the relay, and provides the supply for the equipment to be operated,
•
i.e., bulbs, solenoids, etc.;
A control circuit, switched on/off by manual switches, used to operate the relay.
•
The part of the relay which is connected to the control circuit consists of the winding of an electro-magnet. When
the control circuit is switched off, the contacts are kept apart by a return spring. When the control circuit is switched
on, a current flows through the coil and a magnetic force is produced. This force, which is stronger than the spring
pressure, pulls the contacts of the relay together, causing the work circuit to operate.
A switch-relay system has two main advantages over a simple switch:
DISTRIBUTION SYSTEMS - ELECTRICAL POWER SYSTEM
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