Digitrax PM74 Manual - Halaman 3

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power supply should also be plugged into the PM74 DC 2mm power jack. .

Plug in an active LocoNet to either PM74 RJ12 connector. The red OPS LED

will light up when connected. Any good LocoNet message seen will cause

the red PM74 OPS LED to blink OFF briefly. With no LocoNet the PM74 will

still provide Power Management, with Occupancy and Transponding detec-

tion indicated on just the status LEDS.

Press and hold down the ID button for about 3 seconds until the ID and OPS

LEDs blink alternately, then release the ID button.

From your system now send a SW command. This SW# will become the

Base address. This sets the value of DS1 Occupancy and Zone reports to this

DS number. The following DS2-DS4 use the next three consecutive num-

bers. The ID and OPS LEDs will stop blinking, showing the PM74 has set the

unit's Base address of DS1 to the number of the SW command you just sent.

This provides initial verification that your PM74 working on LocoNet.

You are now ready to customize your track wiring as detailed in the

next sections.

2.0 Best Practice DS Short Circuit protection:

To wire a PM74 DS for Short Circuit Power management, follow the Figure 1

wiring example of the DS1 track section. Note: the DCC power source provided

by the Booster must be configured for overall short circuit protection of any track,

wires and devices connected to its output by feeders FA and FB.

Figure 1 shows the recommended connection example to operate DS1 of the

example PM74 for intelligent short-circuit Power Management. This is the

factory default setting for all 4 DS connections, providing track short-circuit

protection to both DS RA/RB rails.

This DS1 track wiring is configured with two track feeds from PM74 termi-

nals 1AC and 1BC which power both DS1 RA and RB rails, as defined between

double gap pairs GL and G1. The PM74 monitors any fault current that may

occur on either rails and feeders connected to DS1. This provides best

sensitivity and fault detection reliability.

Always test the fault response of all the rails and feeder wiring to a

short-circuit during installation. The e.g. DS1 relay will click repeatedly

while a fault of sufficient current is detected in that PM74 DS1 section.

Test occupancy detection with 10K ohms or less placed across the rails of

DS1, e.g. a box car with a resistor wheel set. The status led L1 will light

GREEN to indicate that DS1 rails are logically "occupied" and this occupancy

information is reported to LocoNet.

If a transponding decoder is placed in DS1 the L1 led will blink to indicate

that DS1 is occupied and a transponder has been detected. The decoder

address and DS location is reported onto LocoNet.

Boosters have internal fault detection; current levels, state and timing logic

that may interact with any downstream fault protection devices. The PM74

has a fault current trip point at about 4amps in each DS, and are configured

to operate faster than compatible boosters. This means if the PM74 reacts

before the Booster shuts down the fault track voltage disturbance will be

limited to the faulted DS protected by the PM74. While a fault current flows

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