MGE UPS Systems 3.5 to 21 kVA N+1 - Manual (Page 23)

Installation & Operation - Line to Neutral page 2 — 5
Owner’s Manual
2.5.2 DC Input
Normal: -48VDC
Operating Range: -39.5 VDC to -57VDC
This system is designed for battery systems with the positive terminal Earth Ground. All DC breakers are
in the negative DC lines. The system DC terminals are isolated from Earth Ground.
2.5.3 DC Input Circuit Breaker
Due to tremendous amounts of short circuit current available (in excess of 1000A for as long as several minutes!)
from bank(s) of batteries, that supply electrical power to inverter systems, it is extremely important to connect a
properly sized DC circuit breaker at the DC input cable that feeds the inverter system. The following table is pro-
vided as a guide for selecting the proper circuit breaker.
Table 2-2: Line To Neutral Units Suggested DC Circuit Breaker Ratings.
Inverter rating 7 kVA 14 kVA 21 kVA
CB rating 200A 400A 600A
Figure 2-3: Line To Neutral Inverter Receiver Junction Box.
BATTERY
(-)
BATTERY
(+)
JUNCTION
BOX
INVERTER RECEIVER
WITH JUNCTION BOX
BACK VIEW
INVERTER RECEIVER
WITH JUNCTION BOX
SIDE VIEW
GND
L-IN
L-OUT
TB1
N-OUT
N-IN