type of power supply used on a device affects the way power is
wired to the device.
A half-wave device has ground referenced power circuitry. This
means that all half-wave devices share a common ground.
The power circuitry of a full wave device is not ground
referenced. Full wave devices must use dedicated transformers.
Carefully identify the type of power supply used in a device, as
failing to do so can damage the device and the transformer.
Identifying the Type of Supply
It is essential to identify the type of power supply before wiring
power to a device. There are two types of power supplies: halfwave and full wave (full wave is also known as bridge rectified).
Identifying the type of power supply can prevent many
The type of power supply a device uses can be easily
determined by the labeling of the power port. If the power port
is labeled “24~ GND”, then the device uses a half-wave
rectifier. If the port is labeled “24~ 24~”, then the device uses
full wave rectification.
A half-wave rectified signal draws current only from the positive
half of the AC signal. Because of this, devices that use halfwave rectification are ground referenced.
Half-wave devices can be wired from the same transformer,
providing that wire polarity is observed. Crossing wires between
panels can quickly damage both devices and transformers.
Also known as bridge rectified, a full wave rectified signal draws
current from both the positive and negative voltage cycles. Full
wave devices have floating power supplies and are not
referenced to ground.
Full wave devices cannot be wired to the same transformer to
which a half-wave device is connected. Wiring devices in this
manner will create a ground loop and will damage both the
device and the transformer.
Full wave devices must use a dedicated transformer. Do not
wire other devices to the same transformer. Doing so will
damage both the device and the transformer.
Do not ground the transformer of a full wave device.