Grundfos ALR 20/A Ex Leakage Sensor Relay
01Technical Summary
The Grundfos ALR 20/A Ex relay works with the AL05 Ex leakage sensor as a monitored leakage-detection system for submersible mixers, flowmakers, and recirculation pumps. The relay is installed outside the wet or hazardous process area and provides a change-over contact for alarm or motor-control logic when water ingress, sensor-cable faults, or power loss is detected.
02Applications
- Seal monitoring for Grundfos submersible mixers.
- Leakage detection for flowmakers and recirculation pumps.
- Alarm and shutdown interlocking where water ingress could damage the gearbox or seal chamber.
- Replacement of an installed ALR 20/A Ex relay while retaining a verified AL05 Ex sensor circuit.
03Specifications
| Manufacturer | Grundfos |
|---|---|
| Model | ALR 20/A Ex |
| Product Type | Leakage sensor relay |
| Required Sensor | AL05 Ex leakage sensor |
| Nominal Supply | 230 V AC |
| Supply Tolerance | -15% to +10% |
| Frequency | 50-60 Hz |
| Power Input | Approximately 4 VA |
| Relay Output | 1 potential-free change-over contact |
| Maximum Switching Voltage | 250 V AC / 24 V DC |
| Maximum Switching Current | 5 A |
| Maximum Switching Capacity | 100 VA / 100 W |
| Ambient Temperature | -20...+40 deg C |
| Relative Humidity | Maximum 95%, non-condensing |
| Installation Altitude | Maximum 2000 m |
| Enclosure Class | IP20; install in IP54 or better protected cabinet |
| Mounting | 35 mm DIN rail with 10 mm spacing |
| Sensor Circuit | Intrinsically safe [ib Gb] IIC |
04Features
Design and Function
- Detects water ingress into oil through the connected AL05 Ex sensor.
- Responds to water detection, sensor cable break, cable short circuit, and relay supply failure.
- Front LED indicates a detected device fault.
- Potential-free change-over contact supports external alarm or motor-control integration.
- Automatic return to normal operation follows removal of the fault cause.
- Adjustable switching point compensates for cable length, oil type, and ambient conditions.
- Designed for continuous energization and industrial control-cabinet installation.
Verified Identity
- Manufacturer: Grundfos Model: ALR 20/A Ex Product Type: Leakage Sensor Relay
05Compatibility
- Use only with the Grundfos AL05 Ex leakage sensor.
- Install the relay outside the wet zone and in a protected control enclosure.
- Match the 230 V AC supply and the documented sensor-terminal arrangement.
- Connect the change-over contact to the plant alarm or motor-control logic according to the existing safety design.
- Verify the applicable approval marking and certificate against the relay nameplate because approval revisions may differ.
06Maintenance & Replacement
- Record the switching-point setting and all terminal connections before removal.
- Inspect the AL05 Ex sensor cable for breaks, shorts, and moisture-related damage.
- After replacement, test the expected healthy signal and every required alarm or shutdown response.
- Ensure that motor restart behavior is controlled by the plant control scheme and is not made automatically when unsafe.
- Use qualified personnel for installation and hazardous-area verification.
FAQFrequently Asked Questions
What sensor is used with ALR 20/A Ex?
It is designed to operate with the Grundfos AL05 Ex leakage sensor.
Can the relay be installed in the wet or hazardous zone?
No. The relay is installed outside the wet zone in a protected control environment.
What faults can activate the output?
Water in oil, a broken sensor cable, a cable short circuit, and loss of relay power can produce a fault response.
What supply does the relay require?
The documented nominal supply is 230 V AC at 50-60 Hz.
What is the relay output rating?
The change-over contact is rated up to 250 V AC or 24 V DC, 5 A, and 100 VA or 100 W within the documented limits.
Does the relay restart after a fault is cleared?
The relay returns automatically to normal operation; motor restart behavior must be defined safely in the external control system.
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