Symbol reference

Every symbol the diagram palette carries, grouped by what it does — generation, AC distribution, transformers, protection and instrumentation.

The palette in diagram mode holds the symbols a single-line diagram — SLD — is drawn from. Placing one takes two clicks: click the symbol button, then click the sheet where it goes. The symbol lands at that point and becomes an element you can select, move, rotate, group, copy or delete like any other. The tools that do all of that are on Building the single-line diagram.

The diagram symbol palette listing the available equipment and switchgear symbols. — The symbol palette

The names below are the palette's own names, so you can read this page with the palette open beside it. They are grouped here by what the equipment does, which is not necessarily the order the buttons sit in.

Placing a symbol

Click the symbol

One click on the palette button arms that symbol. Nothing is placed yet.

Click the sheet

The symbol lands where you click. Place it roughly — position is easier to correct than to get right first time.

Position and orient it

Switch to ↖ Move to drag it into place, and use ⟲ 90° or a typed angle with ⟳ Apply if it needs turning.

Wire it in

Use Wire to connect it to the bus or to the device beside it.

Label it

Use Text to write the tag and the rating beside the symbol. A symbol carries its shape and its position; everything printed next to it is text you add.

Generation and conversion

The DC end of the plant, and the machine that turns DC into AC.

Symbol	What it represents
PV Module	The photovoltaic modules — drawn once for a string, an array or the whole DC field, depending on how much of the plant the diagram is showing
Inverter	The inverter that converts DC to AC. In a string-inverter design this is the machine standing out in the field; in a central-inverter design it is the machine inside the control room
SMB	A string monitoring box — the field enclosure that collects strings and passes their combined DC output on to a central inverter without converting it

Which of the last two your diagram needs follows from the electrical topology you chose at launch. A string-inverter plant has no string monitoring boxes; a central-inverter plant has both, with the boxes in the field and the inverters in the control room. See Choosing a design mode.

AC distribution

Where the converted output is gathered and where the medium-voltage side begins.

Symbol	What it represents
ACCB	An AC circuit breaker — the breaker that a group of inverters lands on
MV Panel	A medium-voltage panel, the switchgear the transformer feeds and the point the outgoing line leaves from

Transformers

Five transformer symbols, differing in how many windings they show. Pick the one that matches the machine on the drawing rather than the one that looks closest.

Symbol	What it represents
2-winding	A two-winding transformer — one primary, one secondary
3-winding (IDT)	A three-winding transformer. IDT — inverter duty transformer — is the machine that takes the inverter output up to medium voltage, with two low-voltage windings on one core
4-winding	A four-winding transformer, for a machine taking more low-voltage inputs onto a single core
5-winding	A five-winding transformer, the same arrangement extended again
Power Tx	A power transformer — the machine at the step up to the transmission voltage

The winding count is the whole distinction, and it is the part of an SLD an electrical reviewer reads first. A plant whose inverters are paired onto two-input machines and one whose inverters land four to a machine have the same capacity and different drawings.

Protection and switching

The devices that isolate, interrupt and protect. This is the largest group in the palette, and the group that most of a real SLD is made of.

Symbol	What it represents
Lightning Arrester	A lightning arrester — LA — the surge-diverting device on the line
ISO with Earth Switch	An isolator with an earth switch, drawn as one device
isolator with earth	An isolator with its earth connection
VCB	A vacuum circuit breaker
MCCB	A moulded-case circuit breaker
MCB	A miniature circuit breaker
Fuse	A fuse
relay	A protection relay

Two isolator symbols are offered because the two are not the same drawing. The first shows the isolator and its earth switch as a combined device; the second shows the isolator with its earth connection. Choose per the arrangement your drawing standard expects, and use one of them consistently across the sheet.

The three breaker symbols are distinguished by type, not by rating. The rating is something you write beside the symbol with the Text tool — a breaker symbol carries no rating of its own.

Instrumentation and indication

Measurement, metering and the indication a control panel carries.

Symbol	What it represents
Current Transformer	A current transformer — CT — stepping line current down to a measurable value for metering and protection
Voltage Transformer (2-core)	A voltage transformer — VT — with two cores, one for metering and one for protection
VT delta	A voltage transformer in a delta arrangement
Voltmeter	A voltmeter
Voltmeter Selector Switch	The selector switch that points one voltmeter at each phase pair in turn
Multi Function Meter	A multi-function meter — MFM — reading voltage, current, power, power factor and energy in one instrument
CB status	Circuit-breaker status indication — whether the breaker is shown as open or closed
R-Y-B phase indication	Phase indication for the three phases, labelled R, Y and B

Instrument transformers and the instruments they feed are drawn as separate symbols, wired together, because that is how the panel is built: the current transformer sits on the line and the meter sits on the panel door. Draw the transformer on the run, the instrument beside it, and connect them with Wire.

Which symbols arrive pre-rotated

The Inverter and every transformer are placed pre-rotated to 270°, so that they line up with the horizontal bus the rest of the diagram is built along. This holds in both electrical topologies.

Every other symbol in the palette is placed as it is drawn on its button. If one needs turning — an arrester on a vertical drop, a breaker across the bus rather than along it — select it and use ⟲ 90°, or type an angle and use ⟳ Apply.

A symbol that looks turned the moment you place it is almost always an inverter or a transformer, and almost always correct. Check it against the bus before rotating it back.

The symbols auto-build places

Auto-build draws a chain from a small part of this palette — the equipment whose counts and ratings it can read from the plant. Which symbols it uses depends on the electrical topology:

Topology	Symbols in the chain
String Inverter	PV Module, Inverter, ACCB, a transformer, MV Panel, and the grid
Central Inverter	PV Module, SMB, Inverter, a transformer, MV Panel, and the grid

Everything else on this page — the isolators, the breakers, the instrument transformers, the meters and the indication — is yours to add on top of that chain. That is the normal way round: auto-build settles the equipment count and the connection order, and the protection and metering detail is drawing work. See Building a diagram from the plant.

When the symbol you need is not here

The palette covers the equipment a PV plant's SLD normally shows. For anything else — a make-specific device, a customer's own block symbol, a standard symbol your drawing office uses — import it. An imported image is traced into a vector symbol rather than pasted as a picture, so it draws as line art and exports to CAD as real geometry, and it stays available for later sessions.

See Importing diagrams and custom symbols.