6.2.5Test 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.

TEST MODE

 

 

 

STATIC

 

MAINTENANCE

K5

SWITCH

 

BYPASS SWITCH

 

 

 

 

RECTIFIER

BOOST

INVERTER

 

 

CONVERTER

CB1

K1

 

K3

 

 

 

 

 

 

MAINTENANCE

 

 

 

 

BYPASS SWITCH

CHARGER

K2

Main Power Flow

Breakers Contactors

 

Trickle Current

 

 

Closed

CB2

 

 

Energized

 

 

Open

 

 

 

 

De--Energized

 

BATTERY

 

Figure 6 ---6. Path of Current Through the UPS in Test Mode

 

 

 

Powerware 9330 (10 kVA--40 kVA) Installation and Operation

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Powerware 9330 operation manual Test Mode