Piller UK - Dual Output UPS Application Design Guidance

Dual output UPS Application Design Guidance

UPS Application Design Guidance 2

Single Output Configuration

Dual Output Isolated Bus Configuration

UNIBLOCK UBTD Diesel UPS - Operation

In normal operation the load is fed via the coupling choke. The special design of the coupling choke allows a high level of decoupling between the input and output and blocks all harmonics and transient events between the input and output.

The coupling choke is tapped with the UNIBLOCK machine. The generator winding of this synchronous machine ensures the output voltage is kept constant irrespective of the mains voltage. The generator winding feeds the loads with the same dynamic response of an ideal AC supply. Peak currents and high short circuit current (up to 18 times nominal current) can be supplied by the UNIBLOCK machine even in the event of a mains failure.

In the event of a mains failure power flows from the Powerbridge (rotating kinetic energy store) or battery to the load via the UNIBLOCK machine. If the mains does not return then the diesel starts and comes up to speed. The overrunning clutch then closes for a soft start. The load is ramped on to the diesel from the Powerbridge/battery. The Powerbridge is then fully recharged and thus enables the full stabilisation function (i.e. the Powerbridge will stabilise the output frequency during load steps on and off the diesel by providing power or absorbing power as required).

On restoration of the mains, the output voltage is synchronised to the mains and the input breaker closes and the diesel is shut down.

Dual Output Bus Configuration

UNIBLOCK UBTD Diesel UPS - Dual Output Operation

In the basic form the Piller UNIBLOCK UBTD provides 100% of its available output as continuous Uninterruptible Power. However, it is available in alternative forms whereby the power can be split between UPS (Critical Bus) power and Short-Break power like a standby generator - this form is known as Dual Output Bus.

Depending upon the particular design requirements, it is sometimes necessary or desirable to electrically isolate the short break loads from the Critical Bus - this is known as Dual Output isolated bus. In this configuration, the generator winding provides the Critical Bus source and the motor winding of the UNIBLOCK machine becomes a generator for the Short-Break Bus. The two circuits are isolated by virtue of the transformer action between the windings and so the two outputs are electrically isolated. In other circumstances, it can be preferential to use the same alternator for both supplies particularly in MV solutions. This alternative is uniquely available with the UNIBLOCK UBTD system.

Dual Output Bus Medium Voltage Configuration

UNIBLOCK UBTD Module Ratings (Largest Available)