Nivotester FTW325

Summary

Product identification

• Product Name: Nivotester FTW325
• Product Type: Conductive Point Level Switch
• Signal Circuit: Intrinsically safe for connecting to conductive sensors.

Application

• Two-point control (also for hazardous areas)
• Overfill protection for tanks
• Dry running protection for pumps
• Point level detection

Features and Benefits

• Cable monitoring up to sensor
• Adjustable sensitivity range
• ATEX, FM, and CSA approval
• Measuring range up to 200 k
• Alarm relay can be configured as a second point level relay (SPDT)
• Compact housing for easy series mounting on standard DIN rail
• Pluggable terminal blocks for easy wiring
• Supports connection to different supply voltages

Function and System Design

Measuring Principle

The Nivotester supplies a small alternating current to the measuring point via a signal line connected to the ground probe or metal vessel and the probe. When a conductive medium touches the probe, the voltage drops, triggering the relays.

Signal Transmission

The intrinsically safe signal input is galvanically isolated from the power supply and output. The device monitors the cable voltage, and relay switching depends on the configured fail-safe mode. Switching states are indicated by yellow LEDs.

Fail-Safe Modes

• MAX Mode: Relay de-energizes when the level rises above the switch point, a fault occurs, or power fails. Used for overfill protection.
• MIN Mode: Relay de-energizes when the level falls below the switch point, a fault occurs, or power fails. Used for dry running or pump protection.

Function Monitoring

Channel 1 (CH1) includes function monitoring, indicating faults with a red LED and de-energizing relays. Faults are indicated if the measured voltage is too high, such as an interrupted signal line or defective sensor electronics. Cable monitoring is available with specific probe types and can be switched via a DIL switch.

Switching Delay

Configurable via a slide switch: 0.5 s, 3 s, or 5 s. The delay takes effect when the relay picks up.

Fail-Safe Mode Configuration

Separate MIN/MAX settings for CH1 and CH2 are configurable via DIL switches.

Sensitivity Range

Configurable via DIL switches in three resistance ranges:

• up to 1.0 k
• up to 10.0 k
• up to 200.0 k (standard for most liquids) Fine-tuning is done with a trimmer.

Master-Slave Function

For applications with two Nivotester devices in one tank, a DIL switch can configure one as master and the other as slave to prevent phase shift.

Second Output Relay Configuration

The second alarm relay/level relay can be configured as:

• A second level relay for probe 1 (switches identically to CH1 relay)
• A level relay for CH2
• An alarm relay

Measuring System

A basic system includes a probe, the Nivotester FTW325, and a control or signal instrument. Systems can be configured for single-point control, two single-point controls, or two-point control (pump control).

Input

• Measured Variable: Limit signal generated at a MIN or MAX level.
• Measuring Range: Dependent on probe mounting location.
• Input Signal: Galvanically isolated from supply and output.
• Type of Protection: Intrinsic safety [Ex ia Ga] IIC/IIB; [Ex ia Da] IIIC.
• Connectable Sensors: Liquipoint T, FTW31, FTW32.
• Power Supply to Sensors: Via an AC signal.
• Connecting Cable: Two-/three-core, screening not required.
• Cable Resistance: Max. 25  per core.

Output

• Output Signal: Two floating changeover contacts for level alarms.
• Quiescent Current Fail-Safe Circuit: MIN/MAX fail-safe mode selectable.
• Alarm Relay: Floating changeover contact for fault indication, can also serve as a second level relay.
• Switching Delay: 0.5 s, 3.0 s, or 5.0 s when the relay picks up.
• Switching Capacity:
  • AC: Max. 250 V AC, Max. 2 A, Max. 500 VA at cos  ≥ 0.7
  • DC: Max. 40 V DC, Max. 2 A, Max. 80 W
• Operating Life: At least 10⁵ switching cycles at maximum contact load.
• Function Indicators: LEDs for operation (green), fault (red), level alarm 1 (yellow), and level alarm 2 (yellow).

Overvoltage Category

• As per EN 61010: II

Protection Class

• II (double or reinforced insulation)

Signal on Alarm

• Limit relay de-energized, fault indication via red LED, alarm relay de-energized.

Galvanic Isolation

• All input and output channels and relay contacts are safely galvanically isolated up to 150 V AC.

Power Supply

Electrical Connection

• Terminal Blocks: Removable, divided into intrinsically safe (blue, top) and non-intrinsically safe (gray, bottom) connections.
• Sensor Connection: For two-/three-core cable; use commercial instrument or multi-core cable. Cable resistance max. 25  per core. Screened cable recommended if strong electromagnetic interference is expected; connect screening only to sensor grounding.
• Signal and Control Instruments: Connected to lower, gray terminal blocks. Observe spark suppression for inductive loads.
• Supply Voltage Connection: To lower, green terminal blocks. Built-in fuse (AC: T 250 mA / DC: 400 mA). Reverse polarity protection included.

Supply Voltage

• AC Version: 85 to 253 V AC, 50/60 Hz.
• DC Version: 20...30 V AC / 20...60 V DC.

Power Consumption

• AC: Max. 5.2 VA.
• DC: Max. 1.2 W (at 20 V).

Installation

Installation Location

• Must be housed in a cabinet outside of hazardous areas. A protective housing is available for outdoor installation.
• Mount in areas protected from weather, impact, and direct sunlight.

Ambient Temperatures

• Single mounting: –20 to +60 °C (–4 to +140 °F).
• Series mounting (no lateral spacing): –20 to +50 °C (–4 to +122 °F).
• Storage: –25 to +85 °C (–77 to +185 °F).
• Max. four units in protective housing: –20 to +40 °C (–4 to +104 °F).

Climatic and Mechanical Application Class

• 3K3 as per DIN EN 60721-3-3.
• 3M2 as per DIN EN 60721-3-3.

Degree of Protection

• IP20 (as per EN 60529).
• IK06 (as per IEC 62262).

Electromagnetic Compatibility (EMC)

• Interference emission: EN 61326; Equipment Class B.
• Interference immunity: EN 61326; Annex A (Industrial) and NAMUR Recommendation NE 21.

Mechanical Construction

Materials

• Housing: Polycarbonate, light gray (RAL 7035).
• Front Cover: Polypropylene PPN, blue.
• Fixing Bracket: Polyamide PA6, black (RAL 9005).

Terminals

• 4 screw terminals: probe supply.
• 3 screw terminals: limit relay.
• 3 screw terminals: alarm relay/level relay.
• 2 screw terminals: power supply.
• Connection Cross-section: 1 x 2.5 mm² (1 x 14 AWG) or 2 x 1.5 mm² (2 x 16 AWG).

Weight

• Approximately 145 g (5.11 oz).

Operability

Operating Concept

On-site configuration using switches behind a folding front panel.

Display Elements

• Green LED: Standby.
• Red LED: Fault indication.
• Yellow LED: Level relay 1 picked up.
• Yellow LED: Level relay 2 picked up.

Operating Elements

• A (Slide Switch): Configure time delay (0.5 s, 3.0 s, 5.0 s).
• B (DIL Switches 1-3): Adjustable resistance ranges (up to 1.0 k, up to 10.0 k, up to 200.0 k).
• B (DIL Switch 4): s (pump control) function.
• B (DIL Switches 5 & 6): Channel 1 (CH1) and Channel 2 (CH2) MIN/MAX configuration.
• B (DIL Switch 7): Cable monitoring on/off.
• B (DIL Switch 8): Master/slave configuration.
• C: Output 2 Configuration (Second level relay for CH1, Level relay for CH2, Alarm relay).
• D (Trimmer): Adjustment/Calibration.

Certificates and Approvals

• CE Mark: Confirms compliance with relevant EC directives.
• Overfill Protection: WHG approval.
• Type of Protection: II (1) G [Ex ia Ga] IIC/IIB; II (1) D [Ex ia Da] IIIC.
• Ex Approval: Information on versions for hazardous areas available from Endress+Hauser Sales Centers. Specific explosion protection data are in separate documents.

Other Standards and Guidelines Observed

• EN 60529: Degrees of protection provided by enclosures (IP code).
• EN 61010: Safety requirements for electrical equipment for measurement, control, and laboratory use.
• EN 61326: EMC requirements.

Ordering Information

Further configuration details are available on Endress+Hauser product pages.

Accessories

Protective Housing

• IP 66 protection class.
• Dimensions: W 180 / H 182 / D 165 mm.
• Color: Light gray RAL 7035.
• Part number: 52010132.

Documentation

• Technical Information: TI00375F (Conductive point level probes), TI00367F (Protective housing).
• Operating Instructions: KA00199F (Nivotester FTW325), KA00203F (Liquipoint T - separate), KA00204F (Liquipoint T - compact).
• Certificates: ATEX (XA00196F), DIBt (ZE00043F for Nivotester, ZE00257F for Liquipoint T).

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Disclaimer: This extraction may miss figures, footnotes, or revisions. Contractual data must match the OEM PDF revision used on the project.

Official datasheet (PDF)

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