Specifications

U-ENS00011_99AtypSMSSpec_Rev2.doc

U-ENS00011 Rev2 12/9/08

wrap-around cont actor shall derive po wer from an upstream bypass feed contactor

internal to the UPS module. The wra p-around contactor shall be electrically connected in

parallel to the static switch and shall, at the same time as the static switch, be energized

and upon closure maintain the critical load feed from the bypass source. T he static

sw itch shall only be utilized for the tim e needed to energize the wrap-around contactor

therefore increasing reliability. The bypass circuit shall be capable of supplying the

UPS rated load current and also provide fault clearing current capabilities. The UPS

system logic shall employ sensing which shall cause the static switch to energize within

150 microseconds therefore pro viding an uninterrupted transfer to the bypass source

when any of the following limitations are exceeded:

1. Inverter output undervolt age or overvoltage.

2. Overloads beyond the capability of the inverter.

3. DC circuit undervoltage or overvoltage.

4. Final voltage of system battery is reached (bypass source present and available).

5. System failure (e.g.: logic fail, fuse blo wn, etc.).

B. Automatic Re-transfers

In the event that the critical load must be transferred to the bypass source due to an

overload, the UPS system logic shall monitor the overload condition and, upon the

overload being cleared, perform an automatic re-transfer back to the in verter output.

The UPS system logic shall only allow a re-transfer to occur three times within a five

minute period. Re-transfers shall be inhibited on the fourth transfer due to the likelihood

of a recurring problem at the UPS load distribution. All retransfers will be inhibited if the

inverter and static bypass line are not synchronized.

C. Manual T ransfers

The UPS shall be capable of transferring the critical load to/from the bypass source via

the front control panel. If performing manual retransfers to inverter or automatic

retransfers, the UPS system logic shall force the inverter output voltage to match the

bypass input voltage and then parallel the inverter and bypass sources providin g a

make-before-break transition allowin g a controlled walk-in of load current to the inverter.

Manual transfers will be inhibited if the inverter and static bypass line are not

synchronized.

D. Static Switch

The static switch shall be a high speed transfer device comprised of naturally

commutated Thyristors. During manual transfers the static switch is not required. The

static switch shall not use fuses for protection.

2.2.5 Operation/Display Panel

The control panel shall employ the use of a touch screen interface which allows lock-out of

all UPS control function for security (The Emerge ncy Power Off function shall not be

locked out). The operator interface shall provide the following:

1. UPS start-up procedure

2. UPS shutdown procedure

3. Emergency Power Off (EPO)

4. Audible alarm silence