Intellisys (SG/SE/SGN)
Legacy but VERY common in the field — millions deployed. Board-level repair shops still support Intellisys.
- IR SSR (Sierra) 15–200 hp
- MM/EP 50–300 hp
- Older Nirvana packages (pre-Xe)
- Load/unload with modulation option
- Automatic restart after power failure (jumper selectable)
- Total hours + loaded hours
- Sequencer input for lead-lag
- Intellisys Communications (proprietary RS-485)
- Modbus RTU (via gateway option)
- Airend discharge temp (thermistor)
- Package discharge pressure (4–20 mA)
- Sump pressure
- Cooler cleanliness & ambient
- Coolant level and thermostat valve
- Verify sensor with meter
- Confirm ΔP reading vs actual
- Replace separator on next PM
- Contactor mechanical
- Aux contact block
- Overload reset
- Check remote wiring
- Verify auto/manual selector
- Confirm inlet valve pilot
Fault list is non-exhaustive and firmware-dependent. Always confirm against the controller’s on-screen help or OEM manual.
- Terminal strip J1–J6 for sensor & starter I/O — pin map varies SSR vs MM/EP
- Ground the shield of RS-485 at one end only
Pinouts distilled from OEM wiring diagrams. Exact silk-screen labels and pin numbering vary by hardware revision and package options — always confirm against the machine’s as-built wiring diagram before landing a wire.
- J1 – 24 VDC control power in from unit transformer
- J2 – RTD / thermistor sensor harness (airend discharge 2ATT, injection temp)
- J3 – 4–20 mA transducer harness (package discharge 1AVPT, sump 2AVPT)
- J4 – digital outputs to starter (1M main, 1S star, 1D delta, 1SV load solenoid)
- J5 – digital inputs (remote start/stop, sequencer lead, emergency stop chain)
- J6 – RS-485 Intellisys Communications (proprietary bus to lag machines)
| Pin | Signal | Type | Connects to |
|---|---|---|---|
| 1 | +24 VDC | 24 VDC | T1 control transformer |
| 2 | 0 V | 24 VDC ret. | T1 control transformer |
| Pin | Signal | Type | Connects to |
|---|---|---|---|
| 1 / 2 | 2ATT airend discharge | thermistor / RTD (frame-dep.) | 2ATT sensor |
| 3 / 4 | Injection temp (option) | thermistor | Injection sensor |
SSR-EP thermistor, MM & later PT100 — cross-wiring reads as immediate high-temp shutdown.
| Pin | Signal | Type | Connects to |
|---|---|---|---|
| 1AVPT +/− | Package discharge | 4–20 mA | 1AVPT transducer |
| 2AVPT +/− | Sump pressure | 4–20 mA | 2AVPT transducer |
| Pin | Signal | Type | Connects to |
|---|---|---|---|
| 1M | Main contactor coil | 24 VDC out | 1M main contactor |
| 1S | Star contactor coil | 24 VDC out | 1S star contactor |
| 1D | Delta contactor coil | 24 VDC out | 1D delta contactor |
| 1SV | Load solenoid | 24 VDC out | Blowdown / load solenoid |
| Pin | Signal | Type | Connects to |
|---|---|---|---|
| RS+/RS− | Remote start | dry contact in | Customer PLC |
| RE+/RE− | Emergency stop chain | dry contact in | E-stop pushbutton |
| SEQ | Sequencer lead input | dry contact in | IR sequencer output |
- Membrane keypad and VFD display are the most common controller failures — kits still available
- EPROM revisions have subtle setpoint differences — record firmware before board swap
Setup mode requires holding Set + Display + Enter for ~5 seconds. No numeric password — access is by key combination. Older revs had a hidden factory menu accessed by holding additional keys during power-up (IR service tech only).
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