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20
Installation Guidelines
3.2
Wiring and Protection Devices
For safety reasons, all T800 subracks must be fitted with a protection device (fuse or cir-
cuit breaker) positioned after the output of the T809-10 power supply. The T809-10 out-
puts a high current when overloaded – up to 48A for an output short circuit.
3.2.1
Protection Device Positioning
The location of the DC output protection device depends on whether or not the remote
sense feature is used – refer to Sections 3.2.1.1 (When Remote Sense Is Not Used) and
3.2.1.2 (When Remote Sense Is Used).
3.2.1.1
When Remote Sense Is
When the remote sense is not used, the DC output protection device should be located
as close as possible to the output of the power supply, as shown in the diagram:
Power supply
3.2.1.2
When Remote Sense
When installing a protection device with the remote sense connected:
• Connect the sensing wires to the
device. Failure to do this will cause the power supply to shut down if the
protection device opens the circuit. This happens because the power supply
senses 0V across the remote sense terminals and the output voltage then
increases to compensate for the apparent reduction.
• Connect the sensing wires as close as possible to the load terminals to
ensure the remote sense feature functions effectively.
As a consequence of applying these procedures, the protection device will be located
close to the load, as shown in the diagram below (Figure 3.2).
November 2004
Not
Used
Protection
device
+V
–V
Heavy gauge wire
Figure 3.1 Protection device without remote sense
Is
Used
Load
(e.g. transmitter)
+
–
power supply side
Copyright © 2004 Tait Electronics Ltd
MBZ-00001-01
of any protection
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