We have purchased an Uninterruptible Power Supply (UPS) to run the control computer, telescope, and external hard drives.

The UPS must have to capacity to handle the total power load of all the dependent systems.  Those loads are:

The Roof Motor and the enclosure A/C unit do not run off the UPS.

The UPS we have is a Powerware 9125 (5000/6000 VA) UPS, manufactured by Eaton, serial number TB261A0351.  The UPS is matched with a Powerpass Distribution Module (PDM or PPDM), type L5-30.  The UPS system must not only smooth the incoming power flow and provide battery backup for our system, it must convert the 220V, 50Hz South African power to the 110V, 60Hz power that our American equipment uses.  In our setup, the UPS converts the frequency, and the PDM steps down the voltage.  Furthermore, the PDM has it's own batteries, so the UPS itself can be hotswapped, while the PDM maintains the power.

Installation

The installation of the UPS and PDM followed the user's manuals.  We installed the UPS internal batteries which were shipped separate from the UPS itself.  We then followed the steps for the Plug-Receptacle PDM Installation.  We left the bypass switch on the PDM in the 'Normal' position, and left the Voltage switch in the 240W position.  We left the Neutral-to-Ground Bonding screw on the UPS attached, removed all circuit breaker ties, and switched the battery circuit breakers to the ON position.

We attached the necessary plugs, and then plugged in the power.  NOTE: We had to modify the end of the UPS detachable power cord from the L6-30 setting to a standard 3-prong South African power plug.

We followed the Configuration steps for the UPS and set the UPS output Voltage to 220V, which, when combined with the Voltage switch on the PDM being in the 240V position, yields 110V output from the PDM.  We confirmed the 110V output with a voltmeter before attaching our equipment.

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