Alpha Technologies XM3-HP Series - Technical Manual - Manual (Page 25)

25 017-882-B0-001 Rev. C2 (10/2013)
1.0
Introduction
The optional AlphaDOC adds a second isolated output to the Power Supply. It provides programmable
current limits for two output channels and protects system components by shutting down the load
during overcurrent and short circuit conditions.
The AlphaDOC has a programmable overcurrent threshold (3A-25A) and overcurrent tolerance period
that specifies the time (20-9900ms) an overcurrent condition is permitted before shutting down.
The programmable retry limit can be programmed to select how many times (0-40) after a
programmable delay (5-301 seconds) the AlphaDOC will attempt to reconnect an output once it
has been shut down. When the limit is reached, the XM3 Power Supply automatically retries once
every 30 minutes until the fault clears.
Adding the AlphaDOC to the Power Supply provides these advantages:
A second isolated output: The main purpose of the AlphaDOC is to limit the impact of a
fault condition in one output channel. If a fault condition occurs in a Power Supply (without
the optional AlphaDOC installed) the entire customer network can be affected. The AlphaDOC
option affords protection to one output should a fault condition exist on the other. This gives
you flexibility to isolate Output 1 from Output 2.
A current for critical loads: With the AlphaDOC option, you can designate one output
as the primary connection and the other output as the secondary connection. Commonly,
critical loads are connected to Output 1 as the primary feeder. Using the overcurrent limit
settings, you can ensure the primary output always provides the necessary power. For
example, on a 15 Amp Power Supply, if a customer needs 10 Amps available on Output 1,
the overcurrent limit for Output 2 is set at 5 Amps, so regardless of Output 2, 10 Amps will
remain available for the primary Output 1.
Additional current protection: The standard Power Supply current limit protection is
provided by the fold-back characteristics of the transformer (150% of rated output). The
150% current limit may exceed the ratings of active devices in the cable network and
cause failures. You can lower the maximum current provided at each output by lowering the
overcurrent limit of each respective output. Therefore, to minimize failures due to excess
current supply, set the overcurrent limit to a value below the maximum current the active
components can tolerate.
For example, on a 18A Power Supply, where both outputs are programmed to 10A maximum
and both outputs are supplying 10A, neither output is “in violation” but the total system at 18A
is operating at 111% of its rated output. In this example, after 30 minutes, the Power Supply
will begin a “load shedding” algorithm. The first action is to disconnect Output 2. If this does not
correct the system overload, the next action is to disconnect Output 1.
Power Supply Load
918 All Other Models Permitted Duration of Load
>125% >150% 30 seconds
113% to 125% 125% to 150% 10 minutes
108% to 113% 115% to 125% 30 minutes
<108% <115% Several months
1.3 Alpha XM3-HP CableUPS Layout, continued
1.3.3 AlphaDOC (PIM)
1.0 Introduction, continued
Table 1-3, Duration of Load
The table below depicts a condition in which no DOC is installed, or no individual output is above
its trip setting.
NOTE: