bonitron M3460, Customer Reference Manual

Page: 55 / 68

D_M3460_D_CMAN_vall_00a 4/17/2020
55
7.2.1. E
NERGY
R
EQUIRED FOR
O
UTAGE
The total energy required for the event must be calculated first.
Using the following equation, the total number of joules required for the outage
can be calculated:
J
Out
= P
sys
∗ T
out
We will use a specification of 100 hp. for a 2 second outage for this example.
For instance, a 100 hp drive outage for 2 seconds would be
P
sys
= 100hp ∗ .746 kwatts horsepower
⁄
= 75kW
The total number of joules required is:
J
Out
= 75kW ∗ 2s = 150kJ
7.2.2. M
INIMUM
C
APACITOR
B
ANK
V
OLTAGE
There is a minimum voltage level that must be maintained at the end of the
discharge during backup. An M3460R has, for a 460VAC nominal system, a
minimum input voltage of 320VDC. Therefore, the final discharge voltage of
the capacitor bank (
𝑉
𝑒𝑛𝑑
) should be 320 VDC.
These data are available in the specifications for the specific M3460R by
nominal system voltage.
7.2.3. P
EAK
C
URRENT
The peak current from the capacitor bank will occur at the minimum voltage.
This can be estimated from the equation
I
peak
=
P
sys
V
end
For our example,
I
peak
=
75kW
320Vdc
= 235A