Control Circuit Diagram Reading Handbook
A four-page handbook for maintenance engineers, panel builders and PLC programmers, especially when the drawing set comes with a Japanese machine. The first seven tables are for reading: the three contact types and their Japanese names a接点, b接点 and c接点; eleven JIS device codes (MC, THR, MCCB/NFB, PB, PL, TLR, LS and more) mapped to IEC codes; terminal numbers A1–A2, main contacts, and 95‑96 / 97‑98 on the overload relay; eight rules for reading a ladder, including the vertical layout common on Japanese drawings; how the power circuit 主回路 differs from the control circuit 制御回路; one JIS rung translated symbol by symbol into a latching start circuit; and four steps for tracing a fault from the symptom. The next four tables are for selecting and wiring: ON-delay, OFF-delay, one-shot and flasher timers with their TON/TOF/TP equivalents; push-button and pilot-lamp colours; and whether each signal should use NO or NC, judged by what the machine does if the wire breaks. The last three cover wire-numbering rules, the minimum columns of a terminal list, and eleven Japanese terms common on electrical drawings, followed by an eleven-point checklist. Distilled from ten articles in the Learn Automation with MINATA series.
What is inside
- NO, NC and changeover contacts — a接点, b接点, c接点
- JIS and IEC device codes
- Contactor and overload relay terminal numbers
- Rules for reading a control diagram
- Power circuit 主回路 vs control circuit 制御回路
- Translating a JIS rung into familiar logic
- Fault tracing with the diagram: four steps
- Timer relays and TON / TOF / TP
- Push-button colours
- Pilot-lamp colours
- NO or NC for each signal
- Wire numbers and device tags
- Terminal list
- Japanese vocabulary on electrical drawings
- Checklist for a new drawing set
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