ResourcesSingle-line diagram symbolsPower supply single-line diagrams
Standby generator and transfer switch
Utility and generator incomers, automatic transfer switch, essential and non-essential boards, controller and schedules.
Free to use and modify in your own projects, including commercial ones. The ZIP holds the sample drawing, a template, a plot style table and a README; no add-in needed. The data in the drawing is made up, so it is not for design or construction. Provided as is, without warranty. Library terms (CXL-1.0)
This sample uses these resources
The symbols are blocks from our own libraries, with their attributes filled in. The sheet and its title block come from our ISO A3 title block template. Download them to draw your own diagrams.
Layers, styles and sheet setup are the same for every drawing in the series; they are described on the series page: Power supply single-line diagrams
Title block fields
The attributes of the title block.
| Attribute | Field on the sheet | Value in this sample |
|---|---|---|
| COMPANY | COMPANY | CADXChange |
| PROJECT | PROJECT | Northgate Office Building |
| AREA | AREA | Main switchroom |
| SYSTEM | SYSTEM | 400 V / 50 Hz |
| CLIENT | CLIENT | Sample |
| TITLE | DRAWING TITLE | Standby generator and transfer switch, single line |
| DRAWING_NO | DRAWING NO. | E-821 |
| CONTRACT_NO | CONTRACT NO. | — |
| REV | REV | A |
| DRAWN | DRAWN | — |
| CHECKED | CHECKED | — |
| APPROVED | APPROVED | — |
| DATE | DATE | 2026-11-01 |
| SCALE | SCALE | NTS |
| SHEET | SHEET | 1 |
| OF | OF | 1 |
Revision table: R1 to R4, each with REV, DATE, DESCRIPTION and BY (16 attributes, empty in this sample).
Blocks in the drawing
The equipment list of the drawing: block name, symbol and how many times it is placed.
| Symbol | Block | Placed |
|---|---|---|
 Moulded case circuit breaker | PWR_LV_MCCB | 9 |
 Motor, induction | PWR_MOTOR_IM | 3 |
 Load (static) | PWR_LOAD | 3 |
 Current transformer | PWR_CT | 2 |
 Ammeter | PWR_M_A | 2 |
 Power meter, multifunction | PWR_M_PM | 2 |
 Grid infeed (utility source) | PWR_GRID | 1 |
 Diesel generator set | PWR_GEN_DIESEL | 1 |
 Air circuit breaker | PWR_CB_ACB | 1 |
 Automatic transfer switch | PWR_ATS | 1 |
 UPS | PWR_UPS | 1 |
 Lighting load | PWR_LOAD_LIGHT | 1 |
 Contactor | PWR_CONTACTOR | 1 |
Equipment schedule
One row per placed symbol, read from the attributes of the blocks in the drawing: what is shown on the sheet, and the schedule attributes that were filled in but are not shown.
| Tag | Description | Shown on the sheet | Filled in, not shown |
|---|---|---|---|
| G1 | Grid infeed (utility source)PWR_GRID | RATING = 400 V | VOLTAGE_KV = 10 |
| QF1 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 630 A | VOLTAGE = 400 VBREAKING_KA = 50TRIP_UNIT = Thermal-magneticPOLES = 3 |
| TA1 | Current transformerPWR_CT | RATIO = 630/5 A | CLASS = 0.5BURDEN_VA = 10CORES = 1RATED_KV = 0.72 |
| PA1 | AmmeterPWR_M_A | RANGE = 630 A | ACCURACY_CLASS = 1INPUT = 5 AOUTPUT = Display |
| PM1 | Power meter, multifunctionPWR_M_PM | RANGE = kWh | ACCURACY_CLASS = 0.5INPUT = 5 A / 400 VOUTPUT = Modbus RTU |
| GS1 | Diesel generator setPWR_GEN_DIESEL | RATING_MVA = 400 kVA | VOLTAGE_KV = 0.4POWER_FACTOR = 0.8SPEED_RPM = 1500EXCITATION = BrushlessCOOLING = Radiator |
| QF2 | Air circuit breakerPWR_CB_ACB | RATED_KV = 0.4 kV | RATED_CURRENT_A = 630BREAKING_KA = 36INTERRUPTER = AirMECHANISM = Motor-charged springCONTROL_VOLTAGE = 110 V DC |
| TA2 | Current transformerPWR_CT | RATIO = 630/5 A | CLASS = 0.5BURDEN_VA = 10CORES = 1RATED_KV = 0.72 |
| PA2 | AmmeterPWR_M_A | RANGE = 630 A | ACCURACY_CLASS = 1INPUT = 5 AOUTPUT = Display |
| PM2 | Power meter, multifunctionPWR_M_PM | RANGE = kWh | ACCURACY_CLASS = 0.5INPUT = 5 A / 400 VOUTPUT = Modbus RTU |
| ATS1 | Automatic transfer switchPWR_ATS | RATED_CURRENT_A = 630BREAKING_KA = 36INTERRUPTER = Air, 4 poleMECHANISM = Motorised, mechanically interlockedCONTROL_VOLTAGE = 230 V AC | |
| QF11 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 125 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| M1 | Motor, inductionPWR_MOTOR_IM | POWER_KW = 45 kW | VOLTAGE = 400 VPOWER_FACTOR = 0.85STARTING = Star-deltaSERVICE = Fire pump |
| QF12 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 80 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| M2 | Motor, inductionPWR_MOTOR_IM | POWER_KW = 30 kW | VOLTAGE = 400 VPOWER_FACTOR = 0.85STARTING = Star-deltaSERVICE = Smoke extract fan |
| QF13 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 100 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| U1 | UPSPWR_UPS | RATING = 40 kVA | VOLTAGE_KV = 0.4UNITS = 1 |
| QF14 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 100 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| EL1 | Load (static)PWR_LOAD | POWER_KW = 30 kW | VOLTAGE = 400 VPOWER_FACTOR = 0.95SERVICE = Passenger lifts |
| QF15 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 40 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| EL2 | Lighting loadPWR_LOAD_LIGHT | POWER_KW = 15 kW | VOLTAGE = 400 VPOWER_FACTOR = 0.95SERVICE = Life safety lighting |
| KM1 | ContactorPWR_CONTACTOR | RATED_KV = 0.4 kV | RATED_CURRENT_A = 400BREAKING_KA = 10INTERRUPTER = AirMECHANISM = ElectromagneticCONTROL_VOLTAGE = 230 V AC |
| QF21 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 160 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| M3 | Motor, inductionPWR_MOTOR_IM | POWER_KW = 90 kW | VOLTAGE = 400 VPOWER_FACTOR = 0.85STARTING = Star-deltaSERVICE = Chiller |
| QF22 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 125 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| EL3 | Load (static)PWR_LOAD | POWER_KW = 60 kW | VOLTAGE = 400 VPOWER_FACTOR = 0.95SERVICE = Air handling units |
| QF23 | Moulded case circuit breakerPWR_LV_MCCB | RATED_CURRENT_A = 200 A | VOLTAGE = 400 VBREAKING_KA = 36TRIP_UNIT = Thermal-magneticPOLES = 3 |
| EL4 | Load (static)PWR_LOAD | POWER_KW = 80 kW | VOLTAGE = 400 VPOWER_FACTOR = 0.95SERVICE = General power and lighting |
Manufacturer, model and remarks are left empty on every block, ready for your data. The values are examples.
