The Operating Modes Of Ups; The Power Configuration Of Ups - Tescom T-300P Series User Manual

MECHANIC TRANSFER SWITCH (MAINTENANCE BY-PASS): A second, manually controlled, "maintenance
by-pass" supply is also incorporated into the UPS design. Its purpose is to enable the critical load to be powered
from the mains (by-pass) supply while the UPS is shut down for maintenance or troubleshooting.
The load is unprotected against mains power supply aberrations or failure when it is connected to either the
static by-pass or maintenance by-pass supply.
BATTERY CIRCUIT BREAKER: There is a fuse loadbreak switch (externally mounted) between the UPS and
the batteries. The battery is connected to the DC BUS BAR through a fuse loadbreak switch. This switch has
two built-in fuses (one for battery plus, and one for battery minus). This circuit breaker is closed manually.
Also electronic controlled battery circuit breaker (optional) available. This circuit breaker is closed manually
but it contains an under voltage release coil which enables it to be tripped from the UPS control electronics
following certain detected faults. It also has a magnetic trip facility for overload protection.
BATTERY GROUP (CABINET): The batteries associated with the UPS are generally housed in a purpose-built
cabinet located along-side the main UPS equipment. For a long-term efficiency from the batteries, keep them in
room temperature (20°C).

1.2.1 The Operating Modes of UPS

A. Normal Operation (If there is a main) : All relevant power isolators and circuit Breakers
Closed (except mechanical bypass circuit breaker), the load is powered by the UPS. Also during the
normal operation battery charges. This is made by the UPS's rectifier.
B. Battery operation:
During this operation Inverter part of the UPS is converting DC power (from battery group) to AC
power, and feeding the load. Critical load works till the batteries are being empty. At the end of
discharge UPS gives "A7 BATTERY LOW" alarm.If the batteries are fully discharged UPS gives
"A5 BAT.AUT END" message and shutdown. When the mains is restored the UPS returns back to
normal operation.
NOTE: The battery circuit breake"r must be turn to "1" position when the mains is restored. If not in a
second main failure the critical load will be without Voltage.
C. On maintenance by-pass: UPS shutdown but the load connected to the unprotected mains
via the maintenance by-pass supply line.
D. Parallel operation : (optional, need special hardware) At least 2 UPS's is installed to system
for increasing security and redundancy, they operates together and interactive.

1.2.2 The Power Configuration of UPS

The power switch location of the T-300P series UPS's are shown in the figures 1.1-2-3 In the figure 1.2 external
(split) by-pass block diagram is given. Optionally the static and mechanic by-pass line can be connect to a
different 3 phase AC source ( other UPS etc.),and the rectifier input is connected to generator or mains voltage.
If there is no other power supply static and mechanic by-pass line input (S2) and the rectifier input connections
will be connect to each other. (See figure 1.1)
During the normal operation except the maintenance by-pass switch, all the Switches will be at "1-On" position.
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