Alpha Technologies XM2, XM2-HV, XM2-HP - Manual (Page 31)

2.5 Protective Interface Module (PIM)
The optional (PIM) adds a second isolated
output so the Intelligent CableUPS can function
as an N+1 redundant supply system. 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 PIM has a programmable overcurrent threshold (3A-24A) and overcurrent tolerance
period that specifies the time (1-10 secs) an overcurrent condition is permitted before shutting
down.
You can use the programmable retry limit to select how many times (0-40) after a
programmable delay (5-301 seconds) the PIM will attempt to reconnect an output once it has
been shut down. When the limit is reached, the XM2 power supply automatically retries once
every 30 minutes until the fault clears. The PIM also provides N+1 redundancy in system
configurations and programmable dual outputs.
Adding the PIM to the Intelligent CableUPS provides these advantages:
• A second isolated output: The main purpose of the PIM is to limit the impact of a fault
condition in one output channel. If a fault condition occurs in an Intelligent CableUPS
(without the optional PIM installed) the entire customer network can be affected. The PIM
option affords protection to one output should a fault condition exist on the other. This
gives you flexibility to isolate Output 1A and 1B from Output 2.
• A current for critical loads: With the PIM 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 1A 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
1A, 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 (180% of rated output). The
180% 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 15A power supply, where both outputs are programmed to 10A maximum
and both outputs are supplying 9A, neither output is “in violation” but the total system at 18A
is operating at 120% 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 1A and Output 1B (if
used).
Power Supply Load Permitted Duration of Load
>150% 10 seconds
125% to 150% 10 minutes
115% to 125% 30 minutes
<115% Many months
31 017-805-B0-010 Rev. K2