Document 2.4.126, Revision 4
October 2017
3
Three-Phase Padmounted Distribution Transformers
TABLE OF CONTENTS
Important Safety Information
........................................................................................................................2
Section 1: Introduction
.................................................................................................................................5
Section 2: Receiving, Handling and Storage
..............................................................................................….6
Drawings and Documents.........................................................................................................….....6
Lifting and Handling....................................................................................................................…..6
Initial Inspection...........................................................................................................................….6
Fluid Level....................................................................................................................................….7
Internal Inspection.........................................................................................................................….7
Fluid Sampling..................................................................................................................................7
Transformer Storage.....................................................................................................................….8
Section 3: Installation
..................................................................................................................................9
Lifting and Handling.........................................................................................................................9
Jacking, Skidding and Rolling............................................................................................................9
Location and Mounting.................................................................................................................….9
Verifying Enclosure Integrity............................................................................................................10
Grounding.......................................................................................................................................10
High-Voltage and Low-Voltage Connections.......................................................................................10
High-Voltage Connections..............................................................................................................10
Low-Voltage Connections...............................................................................................................11
Section 4: Inspection and Testing Before and After Initial Energization
.........................................................12
Pre-Energization Inspection and Tests..........................................................................................…12
Ratio Test......................................................................................................................................12
Insulation Resistance Test.............................................................................................................12
Tap Changer Setting…………………………………………………………….........................................................12
Series/Multiple or Delta/Wye Switch Settings…………………………………................................................13
Grounding………………………………………………………………………............................................................….13
Bolted Connections……………………………………………………………...................................................….....13
Fluid Level………………………………………………………………………......................................................….....13
Fluid Temperature………………………………………………………………....................................................…...13
Internal Fault Detector...............................................................................................................…..13
Current Transformers…………………………………………………………....................................................…....13
Accessory Wiring……………………………………………………………….....................................................…....13
Tank Finish……………………………………………………………………...........................…............................….....13
Tools……………………………………………………………………………..........................................................…....13
Internal Inspection………………………………………………………………....................................................…..13
Post-Energization Inspection and Tests……………………………………...............................................….....14
Verifying Correct Voltage...........................................................................................................…...14
Checking for Leaks……………………………………………………………...................................................…......14
Observing Operation..............................................................................................................…......14
Checking Gauges………………………………………………………………..................................................…..14
Audible Sound…………………………………………………………………......................................................…....14
Locking the Terminal Compartment…………………………………………….........................................….......14
Section 5: Operation of Switching and Protective Devices
………………................................................................15
Tap Changer……………………………………………………………………...................................................................15
Series/Multiple or Delta/Wye Switch………………………………………….........................................................16
Load-Break Switch…………………………………………………………..................................................................…16
Fuses………………………………………………………………………..................................................................…......16
2
5
6
6
6
6
7
7
7
8
9
9
9
9
10
10
10
10
11
12
12
12
12
12
13
13
13
13
13
13
13
13
13
13
13
14
14
14
14
14
14
14
15
15
16
16
16