Technical Specifications
| Parameter | Value |
|---|---|
| Product Model | 34794901 |
| Alternate Part No. | 347949-01, 347 949 01 |
| Manufacturer | Bitzer (Bitzer Electronics A/S) |
| Product Type | OLC-D1 Optical Level Switch / Oil Level Sensor |
| Measuring Principle | Infrared optical, contactless (prism reflection/absorptio |
| Supply Voltage | AC 115–230 V ±10 % (Order No. 16G 15 OLC 03); AC/DC 24 V ±10 % (16G 15 OLC 04) |
| Power Consumption | 3 VA (50/60 Hz) |
| Output | 1 × SPDT relay, volt-free changeover contact |
| Contact Rating (max.) | AC 240 V, 2.5 A, C300 |
| Contact Rating (min.) | > 24 V AC/DC, > 20 mA |
| Start-up Delay | 3 s ± 1 s (relay picks up after supply applied) |
| Response Delay (level missing / level good / error) | 5 s ± 2 s |
| LED Indication | Red LED: OFF = level good / ON = level low / Flashing = fault |
| Permitted Ambient Temperature | -30 … +60 °C |
| Max. Medium Temperature | +120 °C (up to 16,000 h); +100 °C continuous |
| Max. Operating Pressure | 46 bar @ -10 … +120 °C; 34.5 bar @ -30 … -10 °C |
| Connection Thread | M20 × 1.5 short (15G15 465 01); 1/2″ NPT short (15G15 460 01); 1 1/8-18 UNEF short (15G15 462 01) |
| Housing (screw-in unit) | Steel acc. DGRL, nickel-plated (ammonia-compatible) |
| Housing (evaluation unit) | PA, glass-fibre reinforced |
| Protection Class | IP54 (built-in status; cable outlet pointing downward) |
| Connection Cable | 5 × AWG-18 (0.75 mm²), L = 2 m, colour-coded |
| Mechanical Service Life | Approx. 1 million switching cycles |
| Weight (screw-in unit / evaluation unit) | Approx. 150 g / approx. 220 g |
| Installation Torque | Coupling ring hand-tight, approx. 10 Nm |
Main Features and Advantages
Contactless optical measurement — no moving parts
The defining advantage of the Bitzer 34794901 is that it never touches the oil with a mechanical element. Where a float switch has pivots, magnets, and a reed that can stick or fail after years of slugging, the OLC-D1 measures through a prism using infrared light. There is nothing to foul, seize, or mechanically wear inside the refrigerant circuit — a decisive reliability gain in systems with wax, sludge, or widely varying oil return.
Removable evaluation unit — service without breaking the seal
The screw-in prism remains permanently installed in the compressor, while the electronic evaluation unit of the Bitzer 34794901 screws into it from outside. The evaluation unit can therefore be replaced without opening the reservoir or disturbing the pressure envelope. For a charged system, this means a suspected electronics fault can be resolved without recovery, evacuation, and recharging — a substantial saving in both downtime and refrigerant cost.
Integrated self-monitoring and installation check
The optics inside the Bitzer 34794901 continuously supervise their own condition. An internal fault, an assembly error (prism not properly seated, coupling ring loose), or an under-voltage condition causes the output contact to drop out safely and the red LED to flash — rather than silently continuing to report a good level. A separate installation-check function monitors correct assembly at commissioning, catching wiring and mounting mistakes before the compressor is exposed to risk. This fail-safe behavior is what makes the device suitable for compressor protection rather than indication alone.
Clear, unambiguous diagnostics
The single red LED on the Bitzer 34794901 is a three-state annunciator: OFF = level good, steady ON = oil level low, flashing = internal fault or assembly error. A service technician can therefore distinguish “real oil loss” from “sensor problem” in seconds, without a laptop or a control panel. The 5-second delay on both drop-out and pick-up prevents relay chatter during normal oil-level fluctuation — which the official Bitzer documentation explicitly notes is common in refrigeration systems.
Volt-free SPDT output — universal interfacing
The relay contact on the Bitzer 34794901 is potential-free and SPDT, so it drops directly into any control scheme: interrupt the compressor contactor coil for a hard safety trip, feed a PLC digital input for alarm logging, or drive a beacon and audible alarm. Rated up to AC 240 V / 2.5 A, it requires no external interposing relay in most installations.
Robust pressure and temperature rating
With a nickel-plated steel housing rated to 46 bar and a medium temperature of +120 °C, the Bitzer 34794901 is built for the real operating envelope of compressor crankcases — including ammonia (NH₃) systems, for which the DGRL-compliant steel body is specifically suited. Multiple thread options (M20×1.5, 1/2″ NPT, 1 1/8-18 UNEF) cover Bitzer compressor housings and regional piping standards without adapters.
