Inputs, Outputs And Interface Signals; Power Inputs - Lenel OnGuard Hardware Installation Manual

1

Inputs, Outputs and Interface Signals

Hardware products operate from various power sources and communicate via a variety of I/O interfaces.
Understanding the power requirements and interface signals, their characteristics, merits and limitations will
insure successful installation and a reliable system.
1.1

Power Inputs

1.1.1 AC Power
Some OnGuard hardware products can use an AC power source.
The AC power wiring to power supplies consists of the AC LINE (L), AC NEUTRAL (N), and SAFETY
GROUND (G). These lines from the AC power source to the power input terminals must not be
interchanged.
Interchange of the AC LINE and AC NEUTRAL exposes components within the power supply to the hot
side of the input power even if the AC line switch is turned off. This presents a safety hazard.
Interchange of the AC LINE and SAFETY GROUND places the supply chassis to an AC potential equal to
the input voltage. This could result in a lethal shock hazard or equipment damage.
The interchange of the AC NEUTRAL and SAFETY GROUND may result in ground current flowing
through the power supply chassis and other ground paths, causing unreliable/improper system operation.
The AC LINE input to Hardware power supplies is appropriately fused and switched. Local safety
regulations may require an additional switch/fuse to be installed in the NEUTRAL input.
Do not apply greater than 12 VAC ± 15% to any hardware product.
1.1.2 DC Power
All OnGuard hardware products can use a DC power source.
When using a DC power supply for a hardware product, the DC power must be isolated electrically from the
AC input side and non-switching, regulated DC power. Readers require +5 or +12 VDC, and all other panels
require either 12 VDC or 12 VAC (except the LNL-1300, LNL-1300e, and LNL-8000 which require
12 VDC, only).
DC power must be supplied through a diode for reverse polarity protection, and must be filtered and
regulated for the electronics. Products intended to be powered from DC should never be powered with an
AC transformer with rectifiers.
The Multiplexer requires a regulated, low ripple (under 20 mV P/P). The power input is fused and protected
from polarity reversal, and a crowbar over-voltage circuit protects against application of wrong voltages.
Do not apply greater than 12 VDC ±15% to any hardware product.
To insure reliable operation of all components of the system, it is important that all power supplies used to
power the devices are completely isolated from the AC power source.
Hardware Installation Guide
revision 7 —
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