Isolation transformer used with UPS system are normally Delta to Star type. It provides following benefits.1. It isolates output neutral from source neutral meaning that any other neutral in system having power quality problem will not effect the output neutral and hence the out put voltages.2. Limits the fault current by inclusion of impedance of this transformer in the network.3.Suppresses odd harmonics currents like3rd,9th ,15th and other odd multiples of third harmonic.
