Cresnet Touchpanel Power Q&A - Crestron TPS-3000 Connection Manual

Crestron
Cresnet Touchpanel Power Q&A
Q.
We prefer to place Cresnet power supplies in our "Head End" equipment rack
for large residential systems. It has come to our attention that many of the
newer touchpanels draw considerably more Cresnet power then their
predecessors. (For instance, the TPS-15G-QM draws 75 watts of Cresnet
power.)
Considering power loss (due to resistance) in cable, and the 75 Watt
maximum output of Crestron power supplies, it appears that the maximum
distance between a power supply and a newer touchpanels will be much less
than previous.
1.
2.
3.
A.
1.
TPMC-15CH/QM-(L) and TPMC-17CH/QM-(L) panels are shipped with an
interface module called a TPMC-L-IMC. This interface is used to convert the
power from the panels power supply to two wires, allowing for extensions in
distance between the power supply and the panel. The following chart
illustrates cable-length limitations:
Recommended wire lengths between TPMC-L-IMC and TPMC touchpanel.
14awg (2.5mm)
16awg (1.5mm)
2.
3.
In some cases, it may make sense to use larger gauge wiring for Cresnet
power on long runs.
Crestron Quick Guide to Touchpanel Connections
Why does the TPMC-15/17 (CH/QM) come with its own 12.5 Volt
power supply, instead of using Cresnet power?
Is there any possibility of producing a larger power supply to deal with
the incresed Cresnet power consumption?
Does Crestron have any recommendations or guidelines regarding
power delivery over Cresnet (and other) cable?
The higher resolution, brightness, and added capabilities of the new
Crestron touchpanels have come at a price. More power is needed to
drive these devices. This is especially true for the wired "TPMC"
panels. Their embedded computer capabilities draw a great deal of
power. Their power draw makes it impractical to drive them with 24
Volt Cresnet power. A dedicated 12.5 Volt power supply was chosen
as the best way to supply power.
WIRE GAUGE
The answer is "no". The National Electrical Code prohibits running
more than 75 Watts of Cresnet power through low-voltage wiring.
Larger power supplies could present a fire hazard.
When "sizing up" an installation, pay attention to the touchpanel sizes
and their distance from the main equipment rack.
may be best to locate a power supply local to the touchpanel. In
multi-story projects, utility closet locations should be noted as a
possible site for Cresnet power supplies on that floor.
Quick Guide to Touchpanel Connections
SINGLE WIRE
30ft
20ft
DOUBLE WIRE
60ft
40ft
In many cases, it
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