Template · Commercial and industrial

Medium-voltage service with unit substation single line diagram

13.8 kV breaker with an overcurrent relay, a 1500 kVA transformer and a 2000A 480V switchboard.

A free template with typical ratings, conductor callouts and general notes. Open it, change what differs on your job, fill in the title block and export a PDF.

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Medium-voltage service with unit substation single line diagram: 13.8 kV breaker with an overcurrent relay, a 1500 kVA transformer and a 2000A 480V switchboard. — Medium-voltage service with unit substation. 23 devices on an 11 × 17 in sheet with a title block and notes column.

What the drawing shows

Every device on the sheet, in the order power reaches it.

Symbol	Label	Rating or detail	Conductors feeding it
Utility source	Utility primary	13.8 kV 3φ 3W
Current transformer	Primary metering	Utility CTs and VTs	3 × 1/C #2 Cu 15 kV, concrete-encased duct
Power breaker	1200A	Main breaker, 15 kV · 25 kA
Protective relay	Overcurrent relay
Panel	Primary switchgear	1200A · 15 kV class
Voltage transformer	Voltage transformers	2 × 14,400:120V
Surge protective device	Surge arresters	Rating per utility
Transformer	Transformer T-1	1500 kVA · 5.75% Z, 13.8 kV Δ – 480Y/277V	3 × 1/C #2 Cu 15 kV, + #2 G
Draw-out breaker	2000A 3P	Secondary main, LSIG	5 sets of 4 × 600, kcmil Cu
Instrument	Power meter
Panel	Switchboard MSB	2000A · 480Y/277V 3φ 4W
Circuit breaker	800A 3P	MCC-1
Panelboard	MCC-1	800A · 480V 3φ	2 sets of 3 × 500, kcmil Cu + #1/0 G
Circuit breaker	600A 3P	DP-1
Panelboard	Panel DP-1	600A · 480Y/277V	2 sets of 4 350, kcmil Cu + #1 G
Circuit breaker	125A 3P	T-2 primary
Transformer	Transformer T-2	75 kVA, 480V Δ – 208Y/120V	3 #1 Cu + #6 G
Circuit breaker	225A 3P	Secondary main	4 #4/0 Cu + #4 G
Panelboard	Panel LP-1	225A · 208Y/120V
Circuit breaker	250A 3P	PFC
Capacitor bank	Capacitor bank	150 kVAR · 480V
Circuit breaker	30A 3P	SPD
Surge protective device	SPD	Type 2

Notes on the sheet

Transformer T-1: 1500 kVA ÷ (1.732 × 13.8 kV) = 63A primary; 1500 kVA ÷ (1.732 × 0.48 kV) = 1804A secondary, protected at 2000A.
Relay 50/51 trips breaker 52. Pickup and time settings from the coordination study, within the transformer primary protection limits of the adopted code.
Capacitor bank: 150 kVAR ÷ (1.732 × 0.48 kV) = 180A; conductors and breaker at 135% = 243A, so 250A.
Primary metering, cable terminations and the service entrance arrangement to the utility standard. Secondary neutral bonded at the switchboard as a separately derived system.

Diagram is schematic and not to scale. Field-verify existing equipment ratings. Ratings and conductor sizes shown are typical. Confirm against the adopted code, the equipment listing and a load calculation before installation. Code references are to the 2023 NEC and the 2024 Canadian Electrical Code: see references and editions.