Electrical system and maintenance
Two independent heater channels with shared mains and 24 V control supply
What do you need to do?
Understand the system
Find the mains, 24 V enable, temperature demand and external heater DC paths.
How it works →Build or rewire
Open the electrical diagrams, follow numbered wire connections and identify the correct components.
Build references →Diagnose or repair
Identify the relevant circuit and component from a reported fault or indicator state.
Fault-finding guide →External DC connector references
The drawings use a per-channel IN/OUT convention, while the front-panel manual uses four connector-pair references. Both describe the same connections:
| Channel | Front-panel pair | R1.2 drawing and wiring schedule | Function |
|---|---|---|---|
| 1 | JP1 | JP1-IN | External PSU input (upper pair) |
| 1 | JP2 | JP1-OUT | Heater output (lower pair) |
| 2 | JP3 | JP2-IN | External PSU input (upper pair) |
| 2 | JP4 | JP2-OUT | Heater output (lower pair) |
Verify the permanent markings, polarity and actual circuit continuity on the equipment before connecting or servicing any heater circuit.
Understand the electrical system
These three paths serve different purposes and must be kept separate.
Schurter inlet J1 feeds the Mean Well 24 V supply PS1 and the two Omron controllers through their respective CONTROL selectors. Protective earth bonds the enclosure, door and relevant equipment.
Each Schneider CONTROL selector powers its Finder 13.61 enable circuit. The EAO momentary button toggles that channel's ENABLE. The Omron heat-demand output drives the Weidmüller interface, which controls the Crydom input. ACTIVE indication requires ENABLE and demand together.
Each external DC positive path passes through the Lovato protection device, Finder 62.31 directional contact (terminal 34 to 14), Crydom DC SSR and heater. Heater DC negative returns to its corresponding external supply, separately from the 24 V controls.
Build or rewire the controller
Use these documents in sequence. Each has one distinct purpose.
- Start with the drawings. Open the circuit diagrams for mains, enable, demand and external heater power.
- Identify the parts. The component register is the definitive source of reference designations, manufacturer models and datasheet links.
- Identify terminal connections. The terminal allocation appendix gives the reference arrangement, conductor positions and installation notes.
- Connect and inspect. Use the searchable From → Via → To schedule (70 listed routes), then complete the inspection and commissioning requirements in the distribution guide and risk assessment.
Diagnose or repair
Start with what the controller is doing. Select the relevant documentation instead of searching through several duplicated explanations.
| Observed symptom | Relevant checks and references |
|---|---|
| Omron controller has no display | Check the upstream supply, CONTROL selector and respective AC branch using the mains wiring schedule and device references. |
| ENABLE button does not latch the channel | See EAO SB1/SB2, Finder 13.61 K1/K2, the gated 24 V net and enabled output in the ENABLE circuit schedule. |
| ACTIVE is off despite requested heat | Confirm intended Omron state, enable state and demand path. Use Weidmüller / SSR demand routes and indicator meanings. |
| ACTIVE lights but the heater does not heat | The lamp does not prove heater current. Refer to external PSU state, DC protection, Finder 62.31 and Crydom path in the DC heater wiring schedule. Do not bypass protective devices. |
| Temperature reading is wrong or missing | Check the Type K sensor, connector polarity, Omron error display and approved sensor settings. See Type K parts and Omron guidance. |
| Unexpected output or restart after power returns | Keep heater DC isolated and use the SOP fault procedure. Investigate Omron RESET and Finder enable power-restoration behavior before returning to service. |
For replacement work, match the exact manufacturer part number and verify conductor assignments, protective bonding and functional tests before restarting.
Current R1.2 electrical drawings
R1.2 is the current wiring revision. The complete 14-sheet drawing set is available to view directly on the website or download as PDF and editable PowerPoint.
14-sheet electrical drawings
Current R1.2 PDF and editable PowerPoint, plus supplementary circuit and connection diagrams.
View drawings and downloads →Connection sheets
All 70 numbered From–Via–To routes, with channel filtering on screen.
Open printable connection sheets →Terminal schedule
Reference connection blocks, terminal positions and installation requirements.
Open terminal schedule →Earlier drawings — D13 (archive)
The previous D13 issue has 11 sheets and predates R1.2 wiring changes. It is retained for historical comparison, not for new builds or repairs. View archive · D13 PDF · D13 PowerPoint.