MGE UPS Systems STS 600A - Manual (Page 20)

1.4.1 PMM 2 Plus and PMM 2 Ultra
In the PMM 2 Plus configuration, the input of the PMM 2 cabinet is supplied by the output of the STS. The dual input
distribution system accepts two independent AC input sources feeding to the STS. If the preferred input source
power is not available, the STS will transfer to the alternate input source, avoiding interruption to the critical load.
The output power is conditioned and stepped down to distribution voltage via an isolation transformer, feeding
panelboards or main frame circuit beakers.
In the PMM 2 Ultra configuration, an isolation transformer feeds each STS input source upstream of the STS. The
transformer secondary output of the PMM 2 -1 (left cabinet) supplies the Source-1 input and PMM 2 -2 (right cabinet)
supplies Source-2 input of the STS cabinet. If the preferred source input power is not available, the STS will transfer
to the alternate input source, avoiding interruption to the critical load. The output of the STS connects to the output
busbars of the PMM
2 -1 and PMM 2 -2 cabinets, feeding panelboards or main frame
Figure 1-2: PMM 2 and PMM 2 Ultra Cabinets.
Epilson STS TM
Introduction 1 — 4 86-504004-00 B03