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Magnum VS –48 Vdc User Manual Page 27
GMT Fuses
When a GMT fuse trips, a fuse element burns out allowing the indicator to connect DC power to the alarm contact.
This turns on the fuse alarm LED on the fuse panel indicating the affected group and the Controller reports a fuse
alarm. Each Controller fuse alarm combines alarms from 4 individual fuses:
Fuse F1 to F4: Controller Fuse Alarm 1
Fuse F5 to F8: Controller Fuse Alarm 2
Fuse F9 to F12: Controller Fuse Alarm 3
Fuse F13 to F16: Controller Fuse Alarm 4.
To disconnect a load attached to a GMT fuse, pull the fuse straight out of the fuse holder base.
4.4. Battery Management
Battery Charging
Battery charging is integrated into the dc power system to support the primary function of providing power to the
load. Accurate measurement of battery parameters such as voltage, current and temperature are used to maintain
and protect the batteries attached to the power plant.
Charging the battery at the correct rate reduces battery heating, increases the charge returned to the battery and
prevents excess hydrogen generation or, in the case of Valve Regulated Lead Acid (VRLA) batteries, possible
thermal runaway. The Magnum VS operates as a current limited constant voltage battery charger. The current
limit value is set by the controller’s Battery Maximum Recharge Current parameter and is normally based on the
size of the battery plant in ampere-hours.
Consult the battery manufacturer for the recommended maximum charging current. This is frequently expressed as
a percentage of the battery's 20-hour ampere-hour capacity rating, commonly abbreviated as "C". For example, the
maximum recharge current in amperes may be expressed as 0.2C, 20% C or C/5, all of which are equivalent. If the
battery used has a capacity of 120 Ah, then the 0.2 C max current is 24 amperes. Manufacturers typically specify
max recharge current between 0.1C to 0.3C (C/10 to C/3). Avoid high recharge rates that may induce elevated
battery temperatures that can lead to thermal runaway. A 0.1C max recharge current is generally a conservative
value that will result in a 90-95% recharge in 12-15 hours, depending on the initial depth of discharge. In this case
charging current will begin to taper (reduce) from the current limited value after 3.5 - 7 hours.
Typically four 12-volt batteries are connected in series to form a battery string. The ampere-hour rating for one 12-
volt battery will equal the Ah rating of the string. For multiple parallel strings, add the Ah rating of each string
together to get the total Ah rating.