Powerware 9330 - Manual (Page 85)

6--11 Powerware 9330 (10 kVA--40 kVA) Installation and Operation
164201300 REV. G 061502
6.2.5 Test and Maintenance Bypass Modes
An internal maintenance switch is used to safely supply utility power to the system
output during periods of maintenance or repairs. Before this switch is used, the
UPS should be transferred to bypass and the Power Processing Unit (PPU) should
be turned off. This switch has three positions: UPS (normal), TEST, BYPASS. The
bypass source supplies the commercial AC power to the load directly.
While on internal bypass, when a user rotates the maintenance switch from the
UPS position to the TEST position, the load is wrapped around the UPS, while
power is still supplied to the internal bypass. The static switch remains energized
to support the load should the user rotate the switch back to the UPS (normal)
position. When the maintenance switch is rotated back to the UPS position from
the TEST position, the load is switched back to the internal bypass. If the
maintenance switch is rotated to BYPASS instead of to UPS from the TEST
position, the load remains wrapped around the UPS and power is removed from
the entire upper half of the unit allowing service work to be completed on the unit
safely.
Figure 6---6 shows the path of electrical power through the UPS system when
operating in Test mode and Figure 6---7 shows the path of electrical power through
the UPS system when operating in Maintenance Bypass mode.
CAUTION:
The critical load is not protected while the UPS is in Test or
Maintenance Bypass modes.
CB1
CB2
K1
K5
K3
K2
Open
Closed
Breakers Contactors
Main Power Flow
Energized
De--Energized
Trickle Current
RECTIFIER
STATIC
SWITCH
BOOST
CONVERTER
INVERTER
TEST MODE
CHARGER
BATTERY
MAINTENANCE
BYPASS SWITCH
MAINTENANCE
BYPASS SWITCH
Figure 6---6. Path of Current Through the UPS in Test Mode