Schematex

Single-line diagram (SLD)

Power system one-line diagrams following IEEE 315. Substation and distribution layouts with transformers, breakers, disconnects, buses, and protective relays. For electrical engineering, utilities, and power distribution.

Cannot parse line: utility [label: "Grid 138 kV"]

IEEE Std 315 (ANSI Y32.2) 电气图形符号标准 + IEC 60617 国际标准 + 配电系统图形规范。

Primary References:

  • IEEE Std 315-1975 / ANSI Y32.2-1975: Graphic Symbols for Electrical and Electronics Diagrams (de facto SLD standard)
  • IEC 60617:2025 (BS 3939): International graphical symbols for diagrams
  • ANSI Device Numbering (ANSI/IEEE C37.2): Protection device numbering (e.g., Device 52 = AC circuit breaker)
  • NFPA 70 (NEC): National Electrical Code — service entrance conventions
  • IEEE Std 1584: Arc flash labeling conventions (informational)

注意： Single-Line Diagram 将三相 AC 系统的三条导线简化为一条线表示，从而减少视觉复杂度。所有设备额定值和保护设定值以文字标注形式呈现。

1. Symbol Set

1.1 Power Sources

Utility / Grid Connection

<!-- Arrow pointing down (utility power flowing into system) -->
<polygon points="0,-20 -10,-5 10,-5" fill="white" stroke="#333" stroke-width="2"/>
<text x="0" y="10" font-size="10" text-anchor="middle" font-style="italic">Utility</text>
<line x1="0" y1="-5" x2="0" y2="20" stroke="#333" stroke-width="3"/>

Generator

<!-- Circle Ø32px with "G" label and AC wave symbol -->
<circle cx="16" cy="16" r="16" fill="white" stroke="#333" stroke-width="2"/>
<text x="16" y="13" font-size="13" font-weight="bold" text-anchor="middle">G</text>
<!-- Small sine wave symbol inside circle (bottom half) -->
<path d="M 8,20 Q 11,14 14,20 Q 17,26 20,20" fill="none" stroke="#333" stroke-width="1.2"/>
<!-- Lead wire (top and bottom) -->
<line x1="16" y1="0" x2="16" y2="-10" stroke="#333" stroke-width="2.5"/>
<line x1="16" y1="32" x2="16" y2="42" stroke="#333" stroke-width="2.5"/>

Transformer (Two-Winding)

<!-- Primary coil: series of arcs (3 humps), left/top -->
<path d="M 0,0 A 6,6 0 0 1 12,0 A 6,6 0 0 1 24,0 A 6,6 0 0 1 36,0"
      fill="none" stroke="#333" stroke-width="2"/>
<!-- Gap (core gap) -->
<line x1="0" y1="6" x2="36" y2="6" stroke="#333" stroke-width="0.8"/>
<line x1="0" y1="10" x2="36" y2="10" stroke="#333" stroke-width="0.8"/>
<!-- Secondary coil: series of arcs (3 humps), below gap -->
<path d="M 0,16 A 6,6 0 0 0 12,16 A 6,6 0 0 0 24,16 A 6,6 0 0 0 36,16"
      fill="none" stroke="#333" stroke-width="2"/>
<!-- Polarity dots (standard: upper primary = upper secondary same polarity) -->
<circle cx="2" cy="-4" r="2.5" fill="#333"/>  <!-- primary dot -->
<circle cx="2" cy="20" r="2.5" fill="#333"/>  <!-- secondary dot -->
<!-- Lead wires -->
<line x1="18" y1="-10" x2="18" y2="0" stroke="#333" stroke-width="2.5"/>
<line x1="18" y1="16" x2="18" y2="26" stroke="#333" stroke-width="2.5"/>

尺寸: 36px wide × 26px tall（不含引线）

Transformer 标注约定:

  • 额定值: {kVA} kVA, {V_pri}/{V_sec} V, {%Z}% Z
  • 例: 500 kVA, 13.8kV/480V, 5.75% Z

Battery Bank

  • 多组长短平行线（长=正极，短=负极）
  • 3 组标准表示充电电池组

1.2 Switching & Protection Devices

Circuit Breaker (Device 52)

  • 区别于隔离开关: 断弧能力，对角线 + 弧线表示
  • 符号: 对角斜线（左下→右上）+ 上端小弧线
<!-- Body: diagonal line -->
<line x1="5" y1="30" x2="25" y2="5" stroke="#333" stroke-width="2.5"/>
<!-- Arc indicator (distinguishes breaker from switch) -->
<path d="M 25,5 Q 30,0 28,-5" fill="none" stroke="#333" stroke-width="2"/>
<!-- Lead wires (top and bottom) -->
<line x1="15" y1="0" x2="15" y2="-10" stroke="#333" stroke-width="2.5"/>
<line x1="15" y1="38" x2="15" y2="48" stroke="#333" stroke-width="2.5"/>

宽×高: 30px × 38px（不含引线）

标注约定:

  • {kA} kA sym (short-circuit interrupting rating)
  • {A}A trip (trip setting)
  • Device number: 52 (可选）

Disconnect Switch / Isolator (Device 89)

  • 同 breaker 形状，但无弧线（isolation only，不能灭弧）
<line x1="5" y1="30" x2="25" y2="5" stroke="#333" stroke-width="2.5"/>
<!-- No arc → just a simple diagonal line -->

Fused Disconnect

  • 隔离开关 + 保险丝符号的组合
  • 保险丝: 矩形 10×5px（IEC）或小方块（ANSI）

Fuse

<!-- IEC fuse: thin rectangle with wires -->
<rect x="-5" y="-4" width="10" height="28" fill="white" stroke="#333" stroke-width="1.5"/>
<line x1="0" y1="-12" x2="0" y2="-4" stroke="#333" stroke-width="2"/>
<line x1="0" y1="24" x2="0" y2="32" stroke="#333" stroke-width="2"/>

Motor Starter (Contactor with Overload)

  • 矩形盒 20×30px，标注 M 或 MS

Ground Switch

  • 向下指的小三角形（ground 符号）+ 开关线
  • 表示接地刀闸

1.3 Measurement & Protection

Current Transformer (CT)

<!-- Circle Ø14px -->
<circle cx="7" cy="7" r="7" fill="white" stroke="#333" stroke-width="1.5"/>
<!-- "CT" label inside -->
<text x="7" y="10" font-size="7" font-weight="bold" text-anchor="middle">CT</text>
<!-- Primary line passes through center (the single line) -->
<line x1="0" y1="7" x2="14" y2="7" stroke="#333" stroke-width="2"/>

Potential/Voltage Transformer (PT/VT)

  • 同 CT 符号，内标 PT，但与主线连接方式不同（并联，不是串联）

Relay (各类保护继电器)

<!-- Small circle with relay function code -->
<circle cx="10" cy="10" r="10" fill="white" stroke="#333" stroke-width="1.5"/>
<text x="10" y="14" font-size="8" text-anchor="middle">51</text>

常用 ANSI 继电器设备编号：

代号保护类型
27低电压保护 (Under Voltage)
51过电流保护 (Overcurrent)
67方向过电流 (Directional Overcurrent)
87差动保护 (Differential)
79自动重合闸 (Auto Recloser)
81频率继电器 (Frequency Relay)

1.4 Load Devices

Motor

<!-- Circle Ø28px with "M" -->
<circle cx="14" cy="14" r="14" fill="white" stroke="#333" stroke-width="2"/>
<text x="14" y="19" font-size="14" font-weight="bold" text-anchor="middle">M</text>
<!-- Three phase connection points (120° apart, on circle perimeter) -->
<!-- For 3-phase: three small dots at 12, 4, 8 o'clock positions -->
<circle cx="14" cy="0" r="2" fill="#333"/>   <!-- top, phase A -->
<circle cx="26" cy="21" r="2" fill="#333"/>  <!-- lower-right, phase B -->
<circle cx="2" cy="21" r="2" fill="#333"/>   <!-- lower-left, phase C -->

Panel / Load Box (Generic)

<rect x="0" y="0" width="40" height="30" fill="white" stroke="#333" stroke-width="2"/>
<text x="20" y="19" font-size="10" text-anchor="middle">LP-1</text>

Lighting Panel (LP)

  • 矩形 + LP 标注 + panel number

Motor Control Center (MCC)

  • 较大矩形 60×40px + MCC 标注

1.5 Bus Bars

Bus bar 是 SLD 中电压汇集点，用粗水平线表示：

<!-- Bus bar (three-phase, single-line representation) -->
<!-- Thick horizontal line -->
<line x1="0" y1="y_bus" x2="{bus_width}" y2="y_bus"
      stroke="#333" stroke-width="6"
      class="lt-bus-bar" data-voltage="480V"/>
<!-- Bus voltage label (above bus) -->
<text x="{bus_width/2}" y="y_bus-10" font-size="11" font-weight="bold"
      text-anchor="middle" class="lt-bus-label">480V Bus</text>

垂直连接（设备接入 bus）：

  • 设备通过垂直线向下（或向上）连接到 bus bar
  • 连接线宽度 = 标准线宽（2px），比 bus bar 细

1.6 Metering & Instrumentation

元件符号SVG
AmmeterCircle + A<circle r="8"><text>A</text>
VoltmeterCircle + V<circle r="8"><text>V</text>
Power MeterCircle + W<circle r="8"><text>W</text>
Energy MeterCircle + Wh<circle r="8"><text>Wh</text>
Power Factor MeterCircle + PF<circle r="8"><text>PF</text>
Frequency MeterCircle + Hz<circle r="8"><text>Hz</text>

2. Layout Conventions

2.1 Vertical Hierarchy (Power Flow Direction)

SLD 的核心布局原则：电源在上，负荷在下。

┌─────────────────────────────────────────────────┐
│     Utility Source / Generator (top)            │
├─────────────────────────────────────────────────┤
│  ══════ High Voltage Bus (transmission level) ══ │
│         ↓              ↓                        │
│      [TX1]          [TX2]      (transformers)   │
│         ↓              ↓                        │
│  ══════ Medium Voltage Bus ══════════════════════ │
│         ↓              ↓         ↓              │
│      [CB1]          [CB2]     [CB3]  (breakers) │
│         ↓              ↓         ↓              │
│  ══════ Low Voltage Bus (480V/208V) ═════════════ │
│    ↓    ↓    ↓    ↓    ↓    ↓    ↓    ↓         │
│  [M1] [LP1] [MCC] [ATS] ... (loads, bottom)    │
└─────────────────────────────────────────────────┘

2.2 Voltage Level Bands

每个电压等级形成一个水平带（horizontal band）：

电压范围级别典型 band 高度
> 115 kVTransmission120px
1 kV – 115 kVDistribution (MV)100px
< 1 kV (600V)Utilization (LV)80px
< 120VControl/Signal60px

Bus bar 在每个 band 的上部水平绘制。

2.3 Multiple Feeders

同一 bus 上的多个 feeder（馈线）：

  • 等间距从 bus bar 向下延伸
  • 间距：feeder_spacing = 80px（默认）
  • 对称排列（偶数居中，奇数单边）

2.4 Component Sizing Consistency

元件类型标准高度标准宽度
Circuit Breaker40px30px
Disconnect Switch35px30px
Transformer30px40px
Motor30px30px
CT / PT16px16px
Relay22px22px
Bus Bar6px thick100%+ bus width

2.5 Annotation Placement

         [Rating / Equipment ID]
                ↑ 标注在设备上方
    ←── Bus ───[CB]─── Feeder →
                ↓ 额定值在设备下方
         [kA rating / trip setting]
  • Equipment ID: 设备上方，11px bold
  • Rating / kA: 设备下方，10px，{A}A / {kA}kA
  • Voltage label: bus bar 左侧或上方，12px bold
  • Cable annotation: 垂直连接线旁边，9px

3. Annotation System

3.1 Equipment Labels

<!-- Equipment ID (e.g., "CB-101") -->
<text x="x_center" y="y_top - 8" font-size="11" font-weight="bold"
      text-anchor="middle" class="lt-equip-id">CB-101</text>

<!-- Rating (e.g., "800A / 65kA sym") -->
<text x="x_center" y="y_bottom + 14" font-size="9"
      text-anchor="middle" class="lt-equip-rating">800A / 65kA sym</text>

3.2 Transformer Nameplate

Transformer 旁边标注铭牌数据：

<text x="x_right + 5" y="y_top" font-size="9" class="lt-nameplate">500 kVA</text>
<text x="x_right + 5" y="y_top + 12" font-size="9" class="lt-nameplate">13.8kV/480V</text>
<text x="x_right + 5" y="y_top + 24" font-size="9" class="lt-nameplate">5.75% Z</text>

3.3 Cable / Conductor Annotation

<!-- Cable annotation alongside feeder line -->
<text x="x_line + 5" y="y_mid" font-size="9"
      text-anchor="start" class="lt-cable-label"
      transform="rotate(-90, x_line+5, y_mid)">
  3#3/0 AWG, 200A
</text>

4. DSL Grammar (Single-Line Diagram)

document      = header statement*
header        = "sld" quoted_string? NEWLINE

statement     = comment | source_def | bus_def | device_def | load_def
              | connect_def | feeder_def | boundary_def

comment       = "#" [^\n]* NEWLINE

source_def    = IDENTIFIER "=" source_type attrs NEWLINE
source_type   = "utility" | "generator" | "battery"
attrs         = "[" attr ("," attr)* "]"
attr          = "voltage:" voltage_spec
              | "rating:" quoted_string
              | "label:" quoted_string
              | "id:" quoted_string
voltage_spec  = FLOAT "V" | FLOAT "kV"

bus_def       = IDENTIFIER "=" "bus" attrs NEWLINE

device_def    = IDENTIFIER "=" device_type attrs NEWLINE
device_type   = "breaker" | "switch" | "fuse" | "fused-switch"
              | "transformer" | "ct" | "pt" | "relay"
              | "starter" | "contactor" | "mcc"
              | "ammeter" | "voltmeter" | "power-meter"

load_def      = IDENTIFIER "=" load_type attrs NEWLINE
load_type     = "motor" | "panel" | "lighting-panel" | "ats" | "ups" | "load"

connect_def   = IDENTIFIER "->" IDENTIFIER cable_clause? NEWLINE
              | IDENTIFIER "--" IDENTIFIER             # bidirectional (bus tie)
cable_clause  = "[" "cable:" quoted_string "]"

feeder_def    = "feeder" IDENTIFIER "from:" bus_id "to:" load_id
              INDENT device_def+ DEDENT

boundary_def  = "boundary" quoted_string ":" NEWLINE
              INDENT statement+ DEDENT

IDENTIFIER    = /[a-zA-Z][a-zA-Z0-9_-]*/
FLOAT         = /[0-9]+(\.[0-9]+)?/
quoted_string = '"' /[^"]*/ '"'
INDENT        = increase in whitespace
DEDENT        = decrease in whitespace
NEWLINE       = /\n/

DSL 示例：简单工业配电 SLD

sld "Industrial Facility Power Distribution"

# Sources
util = utility [voltage: "13.8kV", rating: "500MVA", label: "13.8kV Utility"]

# Main transformer
TX1 = transformer [rating: "1000 kVA, 13.8kV/480V, 5.75%Z", id: "TX-1"]

# Main breaker
CB-MAIN = breaker [rating: "2000A / 85kA sym", id: "CB-MAIN", voltage: "480V"]

# 480V Bus
BUS-480 = bus [voltage: "480V", label: "480V Main Bus"]

# Distribution breakers
CB1 = breaker [rating: "400A / 65kA", id: "CB-1"]
CB2 = breaker [rating: "400A / 65kA", id: "CB-2"]
CB3 = breaker [rating: "200A / 65kA", id: "CB-3"]

# Loads
M1 = motor [rating: "150HP, 480V, 3ph", label: "Pump Motor M-1"]
LP1 = lighting-panel [rating: "100A, 208/120V", label: "LP-1"]
MCC1 = mcc [rating: "800A", label: "MCC-1"]

# Connections (top-to-bottom power flow)
util -> TX1
TX1 -> CB-MAIN
CB-MAIN -> BUS-480
BUS-480 -> CB1 -> M1 [cable: "3#2/0 AWG, 200ft"]
BUS-480 -> CB2 -> LP1 [cable: "3#4 AWG, 75ft"]
BUS-480 -> CB3 -> MCC1 [cable: "3#2/0 AWG, 150ft"]

DSL 示例：住宅服务入口

sld "Residential 200A Service"

util = utility [voltage: "240V", label: "Utility 240V/120V Split-Phase"]
meter = ammeter [id: "M-1"]
main-cb = breaker [rating: "200A / 10kA AIC", id: "MAIN"]
panel = panel [rating: "200A, 120/240V, 24-space", label: "Main Panel"]

util -> meter -> main-cb -> panel

5. SVG Structure

<svg class="lt-sld" data-diagram-type="sld">
  <defs>
    <style>
      .lt-sld-source    { stroke: #333; stroke-width: 2; fill: white; }
      .lt-sld-bus       { stroke: #333; stroke-width: 6; }
      .lt-sld-breaker   { stroke: #333; stroke-width: 2.5; fill: none; }
      .lt-sld-tx        { stroke: #333; stroke-width: 2; fill: none; }
      .lt-sld-motor     { stroke: #333; stroke-width: 2; fill: white; }
      .lt-sld-wire      { stroke: #333; stroke-width: 2.5; fill: none; }
      .lt-sld-relay     { stroke: #333; stroke-width: 1.5; fill: white; }
      .lt-equip-id      { font: bold 11px sans-serif; fill: #333; }
      .lt-equip-rating  { font: 9px sans-serif; fill: #555; }
      .lt-bus-label     { font: bold 12px sans-serif; fill: #333; }
      .lt-cable-label   { font: 9px monospace; fill: #666; }
      .lt-nameplate     { font: 9px sans-serif; fill: #444; }
      .lt-voltage-band  { fill: #F5F5F5; stroke: none; }
    </style>
  </defs>
  <title>Single-Line Diagram — [name]</title>
  <desc>[description]</desc>

  <!-- Voltage level bands (optional shading) -->
  <g id="lt-voltage-bands">
    <rect class="lt-voltage-band" x="0" y="0" width="{w}" height="120"/>
    <!-- ... -->
  </g>

  <!-- Bus bars -->
  <g id="lt-buses">
    <g id="BUS-480" data-voltage="480V" transform="translate(0, y_bus)">
      <line class="lt-sld-bus" x1="20" y1="0" x2="{bus_end}" y2="0"/>
      <text class="lt-bus-label" x="25" y="-10">480V Main Bus</text>
    </g>
  </g>

  <!-- Power flow wires (vertical feeders) -->
  <g id="lt-wires">
    <line class="lt-sld-wire" x1="x" y1="y1" x2="x" y2="y2"/>
  </g>

  <!-- Devices (breakers, switches, transformers) -->
  <g id="lt-devices">
    <g id="CB-MAIN" data-type="breaker" transform="translate(x, y)">
      <!-- breaker SVG -->
      <text class="lt-equip-id" ...>CB-MAIN</text>
      <text class="lt-equip-rating" ...>2000A / 85kA</text>
    </g>
    <g id="TX1" data-type="transformer" transform="translate(x, y)">
      <!-- transformer SVG -->
    </g>
  </g>

  <!-- Loads -->
  <g id="lt-loads">
    <g id="M1" data-type="motor" transform="translate(x, y)">
      <!-- motor circle SVG -->
      <text class="lt-equip-id" ...>M-1</text>
      <text class="lt-equip-rating" ...>150HP 480V</text>
    </g>
  </g>

  <!-- Metering & protection devices (overlaid on wires) -->
  <g id="lt-metering">
    <g id="CT1" data-type="ct" transform="translate(x, y)">
      <!-- CT circle SVG -->
    </g>
  </g>
</svg>

6. Test Cases

Case 1: Simple Transformer Feeder

sld "Transformer Test"
src = utility [voltage: "13.8kV"]
tx = transformer [rating: "500 kVA, 13.8kV/480V"]
bus = bus [voltage: "480V"]
src -> tx -> bus

验证：utility arrow 在顶，transformer 在中，480V bus bar 在底，垂直连线正确。

Case 2: Circuit Breaker

sld
bus1 = bus [voltage: "480V"]
cb = breaker [rating: "800A", id: "CB-1"]
motor = motor [rating: "50HP"]
bus1 -> cb -> motor

验证：breaker 符号（对角线 + 弧线）在 bus 和 motor 之间，额定值标注正确。

Case 3: Multiple Feeders

sld "Multi-Feeder"
src = utility [voltage: "480V"]
bus = bus [voltage: "480V"]
cb1 = breaker [rating: "200A", id: "CB-1"]
cb2 = breaker [rating: "200A", id: "CB-2"]
cb3 = breaker [rating: "100A", id: "CB-3"]
m1 = motor [rating: "30HP", label: "Pump 1"]
m2 = motor [rating: "30HP", label: "Pump 2"]
lp1 = panel [rating: "100A", label: "LP-1"]
src -> bus
bus -> cb1 -> m1
bus -> cb2 -> m2
bus -> cb3 -> lp1

验证：3 个 feeder 从 bus 等间距向下，各自 breaker + 负荷正确对齐。

Case 4: Full System with Transformer + Protection

（见 Section 4 DSL 示例：工业配电 SLD）
验证：4 层（utility → TX → bus → loads），设备标注齐全，cable 标注侧旁。

Case 5: Residential Service

（见 Section 4 DSL 示例：住宅）
验证：简化 3 元件布局，meter → main breaker → panel，单相配置。

7. Implementation Priority

PriorityFeatureComplexity用户价值
P0 (MVP)Bus bar + vertical wire + utility sourceLowCore — SLD 骨架
P0Circuit Breaker symbolMediumCore — 每个 SLD 必须
P0Transformer symbol (two coils)MediumCore
P0Motor symbol (circle + M)LowCore
P0Vertical hierarchy layout (top-to-bottom)MediumCore
P1Disconnect SwitchLowHigh
P1Equipment labels + ratings annotationsLowHigh
P1Bus voltage labelsLowHigh
P1Multiple feeders from same busMediumHigh
P1Fuse symbolLowMedium
P2CT / PT symbols (inline on wire)MediumMedium
P2Relay circle with device numberLowMedium
P2Lighting panel / MCC boxLowMedium
P2Voltage level band shadingLowMedium
P2Cable/conductor annotationsMediumMedium
P3Generator symbolMediumLow
P3ATS (Auto Transfer Switch)MediumLow
P3Metering instruments (A, V, W)LowLow

6. Expanded Symbol Library (v2): Winding Configurations & Protection Equipment

v1 只有通用变压器和基础开关设备。实际工程 SLD 中，变压器接线方式（Δ-Yg、Y-Δ等）是关键信息，保护设备（避雷器、重合器）也必须专业呈现。

6.1 Transformer Winding Configuration Symbols

变压器符号由两个绕组符号组成，每个绕组用标准接线符号表示。

Winding Symbol Primitives

接线方式符号SVG 描述
Delta (Δ)△等边三角形，边长20px，开口朝下或朝上
Wye grounded (Yg)Y接地Y形 + 底部接地线（三横线）
Wye ungrounded (Y)Y形Y形，无接地线
Zigzag (Z)Z形两段折线，表示延伸三角形接法

Delta (Δ) SVG:

<!-- Equilateral triangle, 20×17px, centered at origin -->
<polygon points="0,-10 -10,7 10,7" fill="none" stroke="#333" stroke-width="2"/>

Wye Grounded (Yg) SVG:

<!-- Y stem: center to top three branches -->
<line x1="0" y1="0" x2="0" y2="-12"/>       <!-- stem -->
<line x1="0" y1="-12" x2="-8" y2="-20"/>    <!-- left branch -->
<line x1="0" y1="-12" x2="8" y2="-20"/>     <!-- right branch -->
<line x1="0" y1="-12" x2="0" y2="-22"/>     <!-- center branch (may omit) -->
<!-- Ground symbol at bottom -->
<line x1="-10" y1="6" x2="10" y2="6"/>
<line x1="-6" y1="10" x2="6" y2="10"/>
<line x1="-2" y1="14" x2="2" y2="14"/>

Wye Ungrounded (Y) SVG: 同 Yg，省去接地符号

Transformer_DY (Delta→Wye Grounded, 最常见)

  • DSL attr: [winding: "D-Yg"]
  • 符号: 上方 Δ (primary) + 下方 Yg (secondary) + 中间 core lines
  • SVG (combined at origin):
<!-- Primary Delta -->
<g transform="translate(0,-20)">
  <polygon points="0,-10 -10,7 10,7" fill="none" stroke="#333" stroke-width="2"/>
</g>
<!-- Core lines (middle zone) -->
<line x1="-14" y1="-4" x2="14" y2="-4" stroke="#333" stroke-width="2"/>
<line x1="-14" y1="0" x2="14" y2="0" stroke="#333" stroke-width="2"/>
<!-- Secondary Wye-Grounded -->
<g transform="translate(0,22)">
  <!-- Y branches -->
  <line x1="0" y1="-8" x2="-6" y2="-14"/>
  <line x1="0" y1="-8" x2="6" y2="-14"/>
  <line x1="0" y1="-8" x2="0" y2="0"/>
  <!-- Ground -->
  <line x1="-8" y1="4" x2="8" y2="4"/>
  <line x1="-5" y1="7" x2="5" y2="7"/>
  <line x1="-2" y1="10" x2="2" y2="10"/>
</g>
<!-- Polarity dots -->
<circle cx="-10" cy="-14" r="2.5" fill="#333"/>
<circle cx="8" cy="18" r="2.5" fill="#333"/>

Transformer_YY (Wye-Wye)

  • DSL attr: [winding: "Yg-Yg"]
  • 符号: 上下两个 Yg 符号 + core lines

Transformer_DD (Delta-Delta)

  • DSL attr: [winding: "D-D"]
  • 符号: 上下两个 Δ 符号 + core lines

Transformer_YD (Wye→Delta)

  • DSL attr: [winding: "Yg-D"]

Autotransformer

  • DSL attr: [type: "auto"]
  • 符号: 单线圈（带中间 tap），两端连线 + tap 引出
<!-- Single winding with center tap -->
<path d="M -12,0 A 4,4 0 0 1 -4,0 A 4,4 0 0 1 4,0 A 4,4 0 0 1 12,0"
      fill="none" stroke="#333" stroke-width="2"/>
<!-- Center tap -->
<line x1="0" y1="4" x2="0" y2="18"/>
<!-- Primary/Secondary terminals are same winding ends -->

Three-Winding Transformer

  • DSL attr: [type: "3winding"]
  • 符号: 三个绕组，第三绕组从中间引出
  • Nameplate: 需在 attrs 中指定 tertiary: "13.8kV/138kV/12.47kV"

6.2 Switching Equipment (v2 Additions)

Recloser (重合器)

  • 描述: 自动重合断路器，检测故障后延时重合（用于配电系统）
  • 区别于 breaker: 加小圆弧 + 循环箭头表示重合功能
<!-- Base: diagonal line (same as breaker) -->
<line x1="-12" y1="12" x2="12" y2="-12" stroke="#333" stroke-width="2"/>
<!-- Arc at top (like breaker) -->
<path d="M 8,-8 A 6,6 0 0 1 16,-8" fill="none" stroke="#333" stroke-width="2"/>
<!-- Reclosing indicator: small circular arrow -->
<path d="M 14,-16 A 6,6 0 1 1 20,-10" fill="none" stroke="#333" stroke-width="1.5"/>
<polygon points="20,-10 22,-14 17,-13" fill="#333"/>  <!-- arrowhead -->

Sectionalizer (线路分段器)

  • 描述: 配合重合器使用，自动隔离故障段（无弧断开）
  • 区别于 switch: 加 "S" 字母 designation
<!-- Base disconnect switch symbol -->
<line x1="-12" y1="12" x2="12" y2="-12" stroke="#333" stroke-width="2"/>
<circle cx="12" cy="-12" r="2" fill="white" stroke="#333" stroke-width="1.5"/>
<!-- "S" label -->
<text x="16" y="-14" font-size="9" fill="#333">S</text>

Ground Switch (接地刀闸)

  • 描述: 安全接地用，通常与断路器联锁
<!-- Diagonal line (switch arm) -->
<line x1="-12" y1="12" x2="12" y2="-12" stroke="#333" stroke-width="2"/>
<!-- Ground symbol at bottom tip -->
<line x1="-12" y1="16" x2="12" y2="16"/>
<line x1="-8" y1="20" x2="8" y2="20"/>
<line x1="-4" y1="24" x2="4" y2="24"/>
<line x1="-12" y1="12" x2="0" y2="16"/>  <!-- connection to ground symbol -->

ATS (Automatic Transfer Switch)

  • 描述: 自动切换两路电源（主用/备用）
  • 符号: 两个断路器符号 + 连接杆（表示联动互锁）
<!-- Source 1 breaker (left) -->
<g transform="translate(-20,0)">
  <line x1="-8" y1="8" x2="8" y2="-8" stroke="#333" stroke-width="2"/>
  <path d="M 5,-5 A 4,4 0 0 1 10,-5" fill="none" stroke="#333" stroke-width="1.5"/>
</g>
<!-- Source 2 breaker (right) -->
<g transform="translate(20,0)">
  <line x1="-8" y1="8" x2="8" y2="-8" stroke="#333" stroke-width="2"/>
  <path d="M 5,-5 A 4,4 0 0 1 10,-5" fill="none" stroke="#333" stroke-width="1.5"/>
</g>
<!-- Mechanical interlock (dashed line between arms) -->
<line x1="-12" y1="-8" x2="12" y2="-8" stroke="#333" stroke-width="1.5" stroke-dasharray="3,2"/>
<!-- "ATS" label -->
<text x="0" y="20" text-anchor="middle" font-size="9" font-weight="bold">ATS</text>

6.3 Protection Equipment (v2 Additions)

Surge Arrester (避雷器 / Lightning Arrester)

  • 描述: 限制过电压，将浪涌电流导入大地
  • IEEE 符号: 下行箭头 + 接地线，或 arc gap + ground
<!-- Vertical line (line connection at top) -->
<line x1="0" y1="-20" x2="0" y2="0" stroke="#333" stroke-width="2"/>
<!-- Surge arrester body: rectangle with arc inside -->
<rect x="-8" y="0" width="16" height="16" fill="white" stroke="#333" stroke-width="2"/>
<path d="M -4,8 Q 0,2 4,8" fill="none" stroke="#333" stroke-width="1.5"/>  <!-- arc inside -->
<!-- Ground connection -->
<line x1="0" y1="16" x2="0" y2="24"/>
<line x1="-10" y1="24" x2="10" y2="24"/>
<line x1="-6" y1="28" x2="6" y2="28"/>
<line x1="-2" y1="32" x2="2" y2="32"/>

Fuse Cutout (跌落式熔断器)

  • 描述: 配电线路上的隔离保护，可视化熔断状态
  • 符号: 椭圆包住对角线（与普通 fuse 区分）
<line x1="-14" y1="14" x2="14" y2="-14" stroke="#333" stroke-width="2"/>  <!-- fuse element -->
<ellipse cx="0" cy="0" rx="10" ry="16" transform="rotate(45)"
         fill="none" stroke="#333" stroke-width="1.5"/>  <!-- enclosure -->

VFD (Variable Frequency Drive)

  • 描述: 变频器，控制电机转速
  • 符号: 矩形块 + "VFD" 标注 + 频率变化符号
<rect x="-20" y="-16" width="40" height="32" fill="white" stroke="#333" stroke-width="2"/>
<text x="0" y="-4" text-anchor="middle" font-size="9" font-weight="bold">VFD</text>
<!-- frequency symbol: Hz or ~→~ with arrow -->
<text x="0" y="8" text-anchor="middle" font-size="8">f₁→f₂</text>

6.4 Metering Symbols (v2)

Watthour Meter (电能表)

<circle r="16" fill="white" stroke="#333" stroke-width="2"/>
<text x="0" y="5" text-anchor="middle" font-size="11" font-weight="bold">Wh</text>

Potential Transformer / Voltage Transformer (PT/VT)

  • 描述: 高电压降低用于测量，与 CT 类似但并联接线
<!-- Smaller transformer: two tiny coil groups side by side -->
<circle r="8" fill="white" stroke="#333" stroke-width="1.5"/>
<text x="0" y="3" text-anchor="middle" font-size="7">PT</text>
<!-- Parallel connection lines (unlike CT series) -->
<line x1="-16" y1="0" x2="-8" y2="0" stroke="#333" stroke-width="1.5"/>
<line x1="8" y1="0" x2="16" y2="0" stroke="#333" stroke-width="1.5"/>

6.5 Generator (Synchronous)

  • 区别于 motor: 圆圈 + "G" 标注（而非 "M"）+ 箭头方向表示发电（输出电能）
<circle r="14" fill="white" stroke="#333" stroke-width="2"/>
<text text-anchor="middle" dominant-baseline="central"
      font-size="12" font-weight="bold">G</text>
<!-- 3-phase output lines at top -->
<line x1="-6" y1="-12" x2="-6" y2="-18" stroke="#333" stroke-width="1.5"/>
<line x1="0" y1="-14" x2="0" y2="-18" stroke="#333" stroke-width="1.5"/>
<line x1="6" y1="-12" x2="6" y2="-18" stroke="#333" stroke-width="1.5"/>

6.6 Updated DSL Examples

sld "Substation with Protection"
  UTIL   = utility [voltage: "115kV"]
  TX1    = transformer_dy [rating: "10MVA", primary: "115kV", secondary: "13.8kV", impedance: "6%"]
  ARR1   = surge_arrester
  BUS1   = bus [voltage: "13.8kV"]
  CB1    = breaker [rating: "1200A", label: "Main Breaker"]
  CT1    = ct [ratio: "600:5"]
  REL51  = relay [device: "51", label: "OC Relay"]
  REL87  = relay [device: "87T", label: "Diff Relay"]
  VFD1   = vfd [rating: "200HP"]
  M1     = motor [rating: "200HP", voltage: "13.8kV"]

  UTIL   -> TX1
  UTIL   -> ARR1   /* surge arrester in parallel */
  ARR1   -> BUS1   /* direct to bus */
  TX1    -> CB1
  CB1    -> CT1
  CT1    -> BUS1
  CT1    -> REL51
  TX1    -> REL87   /* differential relay monitors transformer */
  BUS1   -> VFD1
  VFD1   -> M1

6.7 Updated Implementation Priority (v2)

PrioritySymbolsHours
P0 (v1)utility, transformer (generic), bus, breaker, switch, fuse, motor, load, ct, relay4h
P1transformer_dy, transformer_yy, transformer_dd (winding configs)1.5h
P1surge_arrester, fuse_cl (current limiting)0.5h
P1recloser, sectionalizer0.5h
P1generator (sync), vfd, ats0.75h
P2autotransformer, transformer_3winding0.75h
P2ground_switch, watthour_meter, pt0.5h
P2harmonic_filter, capacitor_bank (switched)0.5h

Total SLD symbols (v2): 37 (P0: 10, P1: 16, P2: 11)

Ladder logic

Industrial PLC programs in IEC 61131-3 ladder logic. Allen-Bradley tag+address+description labels, Set/Reset coil pairs, parallel branches, seal-in circuits. For manufacturing and automation.

Block diagram

Signal-flow block diagrams with summing junctions, gain blocks, feedforward paths, and feedback loops. For control systems, signal processing, and systems engineering.

On this page

1. Symbol Set1.1 Power SourcesUtility / Grid ConnectionGeneratorTransformer (Two-Winding)Battery Bank1.2 Switching & Protection DevicesCircuit Breaker (Device 52)Disconnect Switch / Isolator (Device 89)Fused DisconnectFuseMotor Starter (Contactor with Overload)Ground Switch1.3 Measurement & ProtectionCurrent Transformer (CT)Potential/Voltage Transformer (PT/VT)Relay (各类保护继电器)1.4 Load DevicesMotorPanel / Load Box (Generic)Lighting Panel (LP)Motor Control Center (MCC)1.5 Bus Bars1.6 Metering & Instrumentation2. Layout Conventions2.1 Vertical Hierarchy (Power Flow Direction)2.2 Voltage Level Bands2.3 Multiple Feeders2.4 Component Sizing Consistency2.5 Annotation Placement3. Annotation System3.1 Equipment Labels3.2 Transformer Nameplate3.3 Cable / Conductor Annotation4. DSL Grammar (Single-Line Diagram)5. SVG Structure6. Test CasesCase 1: Simple Transformer FeederCase 2: Circuit BreakerCase 3: Multiple FeedersCase 4: Full System with Transformer + ProtectionCase 5: Residential Service7. Implementation Priority6. Expanded Symbol Library (v2): Winding Configurations & Protection Equipment6.1 Transformer Winding Configuration SymbolsWinding Symbol PrimitivesTransformer_DY (Delta→Wye Grounded, 最常见)Transformer_YY (Wye-Wye)Transformer_DD (Delta-Delta)Transformer_YD (Wye→Delta)AutotransformerThree-Winding Transformer6.2 Switching Equipment (v2 Additions)Recloser (重合器)Sectionalizer (线路分段器)Ground Switch (接地刀闸)ATS (Automatic Transfer Switch)6.3 Protection Equipment (v2 Additions)Surge Arrester (避雷器 / Lightning Arrester)Fuse Cutout (跌落式熔断器)VFD (Variable Frequency Drive)6.4 Metering Symbols (v2)Watthour Meter (电能表)Potential Transformer / Voltage Transformer (PT/VT)6.5 Generator (Synchronous)6.6 Updated DSL Examples6.7 Updated Implementation Priority (v2)