Alpha Technologies FlexNet MPS48-12M - Technical Manual - Manual (Page 12)

12 021-514-B2-001, Rev. A
2.0 Theory of Operation
The FlexNet MPS48-12M multipurpose power supply provides fi ltered output power for a typical
48Vdc telecom bus in switched streetlight applications. During nighttime hours, the power supply
powers the load and charges the batteries. During daytime hours, the MPS48-12C powers the load
from a string of four 12Ah deep cycle batteries.
Metal oxide varistor (MOV) technology provides line voltage surge suppression in the event of line
cross or power spikes. An electromagnetic fi lter conditions line voltage, enabling the power supply to
operate in compliance with FCC Class A standards. The AC-to-DC front end converter feeds power
to the primary winding of a high-frequency isolation transformer. The resulting 48Vdc output, at the
secondary of the transformer, provides power to the load and charges the batteries, keeping them
charged in preparation for streetlight shutdown or line disruption.
Constant voltage is applied to the batteries between -10ºC (14ºF) and -40ºC (-40ºF). MPS48-12C
battery temperature compensation ends at -10ºC (14ºF). A cold weather kit option with battery heater
mat extends battery life in cold environments. Available capacity from the batteries derates from 25ºC
(77ºF) to -40ºC (-40ºF) without the battery mat heater installed as the MPS48-12C continues to power
to the load.
The power module provides over-current, over-voltage, and short-circuit protection. After the fault is
cleared, the power module automatically resumes normal operation to power to the load. The control
logic circuitry provides a LVD (low battery voltage disconnect) function, which prevents the batteries
from becoming overly discharged, detects the presence (or absence) of batteries, performs periodic
battery testing, and communicates status locally with LED status indicators.
The interface module includes:
•
An RJ11/RJ45 pair of connections support the outdoor mesh access points. The RJ11 includes
the RS232 connection to the radio.
• An RJ45 for connection to a remote router or modem (Ethernet backhaul).
• An RJ11 Local Craft Port connection provides a RS232 connection for network management
information.
Radio, Power Ethernet Backhaul Radio, Serial Local Craft
RJ45 RJ45 RJ11 RJ11
Pin Pin Pin Pin
1 Data Pair 1 1 Data Pair 1 1 NC 1 NC
2 Data Pair 1 2 Data Pair 1 2 Radio TX 2 Local RX
3 Data Pair 2 3 Data Pair 2 3 Return 3 Return
4 +Vdc 4 NC 4 Radio RX 4 Local TX
5 +Vdc 5 NC 5 NC 5 NC
6 Data Pair 2 6 Data Pair 2 6 NC 6 NC
7 - Vdc 7 NC
8 - Vdc 8 NC
Preconnectorized cables of varying lengths provide reliable and effi cient fi eld installation. Ethernet,
48Vdc power (with return), and RS232 interface are supported on the preconnectorized cables. The
RJ45 modem/router connection on the power interface module does not access power and return.
The MPS housing is constructed of weather resistant powder coated aluminum. AC service is routed
into the bottom center of the enclosure through a 1/2" Electrical Metallic Tubing (EMT) knockout. The
data and power cables are routed through an adjacent 3/4" EMT knockout using a provided 3-hole
strain relief fi tting. Optional 1/2" and 3/4" knockouts are provided at the back, bottom, and sides of the
enclosure.