Howard Industries HI-105, Instructions Manual

Document 2.4.126, Revision 4

October 2017

13

Three-Phase Padmounted Distribution Transformers

     4.   

Series/Multiple or Delta/Wye Switch 

Settings

—Check series/multiple and delta/

wye switch settings to make sure they are 

set to the correct position. If delta/wye 

or series/multiple connections are made 

using an internal terminal board instead 

of a switch, check to ensure that these 

connections are made properly according 

to the chart on the transformer nameplate. 

Refer to “Opening the Transformer Tank” for 

instructions. 

     5.   

Grounding

—Check to ensure that the 

transformer tank is permanently and 

effectively grounded.  The transformer tank 

ground pad is located inside the terminal 

compartment near the bottom of the tank.  

     6.   

Bolted Connections

—Check all bolted 

connections for tightness, referring to 

nominal torque guidelines contained in 

Tables 1 through 4.

     7.   

Fluid Level

—Check to make sure the fluid 

level is correct as indicated by the fluid level 

gauge or sight plug. If the transformer does 

not have a fluid level gauge or sight plug, 

the fluid level can be checked by temporarily 

removing the liquid-level plug located at the 

25° C mark.

     8. 

 Fluid  Temperature

—Observe the fluid 

temperature gauge and make sure the 

temperature is no lower than indicated 

below before the unit is energized.

 -20°C (-4°F)  for conventional   

  transformer oil

-0°C (32°F)   for R-Temp fluid

-10°C (14°F) for FR3 fluid 

     9.   

Internal Fault Detector

—If the transformer 

is supplied with an Internal Fault Detector 

(IFD), remove the red shipping lock 

after installation and before placing the 

transformer into service.

   10.   

Current Transformers

—If current 

transformers (CTs) are present, connect CT 

leads to the metering load.  If CT leads are 

not connected to a metering load, they must 

be shorted together and grounded before 

the transformer is energized.

   11.   

Accessory Wiring

—Check wiring of control 

and alarm circuits (if supplied) to make 

sure there are no loose connections and no 

damage to wire insulation. 

   12.   

Tank Finish

—Check all painted surfaces 

to make sure that there is no damage or 

corrosion.  

   13.   

Tools

—Check to make sure that all tools and 

equipment are accounted for.

   14.   

Internal Inspection

—The transformer tank 

is sealed and should not be opened unless 

necessary. If the transformer tank must be 

opened, refer to “

Opening the Transformer 

Tank

” for instructions.