APPLICATION NOTES
UltraUPS - #04
Uubypsa2
27 Apr 00
Secure Maintenance Bypass
General________________________________________________________________
Once the user pushes the
knob, the static bypass is
initiated. This reroutes the
load power away from the
inverter and connects it
directly to the source. Note
that the contact on the input
of the inverter is still closed;
this is for both charging the
batteries and operating the
inverter electronics. Now that
the load is assured a
connection to the source via
the static bypass then the unit
can be switched to
maintenance bypass.
Refer to the Maintenance
Bypass mode diagram. Once
the knob is turned, the
contact on the maintenance
bypass loop closes, and both
the static and inverter
contacts open. This forces the
flow of power around the
inverter, so it can be safely
removed from the system
without interrupting the load
is ready for the transition to
maintenance bypass mode.
Turning the knob initiates the
maintenance bypass and the
inverter can now be removed
from the system.
Below are 3 diagrams, which
illustrate how the bypass
works. The first diagram is
Normal Mode, the mode in
which the UPS runs if the
inverter is supplying the
output power. Follow the
solid arrows. Since both
contacts are open on the
maintenance and static
bypass loops, and both
contacts on each side of the
inverter are closed, then the
inverter is supplying the
output power.
In Bypass Security Check
mode, the user pushes in the
knob that triggers the static
bypass. Observe the flow of
the power.
The Secure Maintenance
Bypass is a device that
allows a load connected to
the UltraUPS, to function on
utility power without
interruption if the inverter is
removed.
The Secure Maintenance
Bypass reroutes the flow of
power, bypassing the inverter
and connecting the load
directly to the source. The
Secure Maintenance Bypass
is initiated by pushing and
then turning a knob, located
on the Distribution Module.
The Static Bypass Switch
activates when the knob is
pushed; and an LED
illuminates to indicate it is
safe to continue. This
“secure” feature assures the
user that the load is
connected directly to the
source, and the UPS
Bypass
Security Check
Mode
Normal Mode
Maintenance
Bypass
Static
Bypass
.
Source
Power
Output
Power
Inverter /
Charger
Source
Power
Inverter /
Charger
Maintenance
Bypass Mode
Maintenance
Bypass
Static
Bypass
Source
Power
Maintenance
Bypass
Static
Bypass
Inverter /
Charger
Output
Power
Output
Power
Summary___________________________________________________________
The Security Maintenance
Bypass is a device that allows
the inverter to be removed
from the system, while still
providing uninterruptible
power to the load. The user
activates the maintenance
bypass by pushing and then
turning a knob, which is
located on the distribution
module. When the knob is
pushed, the static bypass is
invoked. Load power is
.
routed away from the inverter
and connected directly to the
source.
Once the UPS indicates to the
user that it is on Static
Bypass, then it is safe for the
user to turn the knob which
switches the unit to
Maintenance Bypass. In this
mode, all power is routed
away from the inverter. The
inverter can now be removed
from the system without
interruption of the load.
The Security Maintenance
Bypass is an essential feature
on the UltraUPS. If
maintenance needs to be
performed on the system, the
inverter can be easily
removed without ever having
to shut off the load. This is
critical if your loads cannot
be interrupted.