Why Choose the Finder 70.61.8.400.0000T Three-Phase Monitoring Relay?
The Finder 70.61.8.400.0000T is a compact and reliable three-phase voltage monitoring relay designed to detect phase failure and incorrect phase sequence in industrial electrical systems. As part of the Finder Series 70 monitoring relay range, this specialist railway-oriented version provides dependable phase supervision for three-phase motors, industrial machinery, electrical control panels and railway electrical equipment.
The relay continuously monitors the connected three-phase supply and checks that all phases are present and arranged in the correct sequence. When an incorrect phase rotation is detected at power-up, the output relay remains de-energised. If a phase is lost during operation, the relay changes its output state, allowing an associated contactor or control circuit to respond to the fault.
With a three-phase 208–480 V AC operating range, a 6 A changeover output contact and a compact 17.5 mm DIN rail housing, the Finder 70.61.8.400.0000T is suitable for electrical installations requiring reliable phase monitoring. Its railway-oriented design is supported by conformity with relevant EN 50155, EN 61373 and EN 45545-2 requirements, making it particularly useful for railway and industrial electrical control applications.
Key Advantages
- Reliable three-phase monitoring relay for phase failure and phase sequence detection.
- 208–480 V AC operating range suitable for a wide range of three-phase electrical systems.
- Detects incorrect phase rotation to help prevent unwanted reverse motor operation.
- Provides phase loss monitoring, including detection under certain phase regeneration conditions.
- 6 A single changeover output contact for control, alarm and interlocking circuits.
- Compact 17.5 mm DIN rail design saves space in electrical control cabinets.
- Railway-oriented construction suitable for applications requiring relevant railway equipment standards.
- Automatic output recovery when acceptable three-phase supply conditions are restored.
Key Features
- Finder Series 70, Type 70.61T monitoring relay.
- Three-phase 208–480 V AC supply and monitoring range.
- 50/60 Hz AC operation.
- Monitoring of phase loss and phase rotation.
- 1 changeover (SPDT) output contact.
- 6 A rated output contact current at 250 V AC.
- Fixed 0.5 s contact actuation delay.
- Positive logic output: the normally open contact closes when the monitored supply conditions are correct.
- Non-adjustable phase detection settings for straightforward operation.
- No fault memory, allowing automatic recovery following restoration of correct supply conditions.
- IP20 protection rating.
- 35 mm DIN rail mounting with screw terminal connections.
- Railway-oriented version conforming to relevant EN 50155, EN 61373 and EN 45545-2 requirements.
Technical Specifications
- Manufacturer: Finder
- Series: 70 Monitoring Relays
- Type: 70.61T
- Model: 70.61.8.400.0000T
- Product type: Three-phase voltage monitoring relay
- Application: Industrial and railway electrical monitoring
- Monitoring functions: Phase failure and phase sequence
- Number of monitored phases: 3
- Operating voltage range: 208–480 V AC
- Supply frequency: 50/60 Hz
- Power supply: From monitored three-phase electrical system
- Output configuration: 1 changeover (SPDT)
- Rated output contact current: 6 A
- Rated output contact voltage: 250 V AC
- Contact actuation delay: 0.5 s
- Phase sequence monitoring: Yes
- Phase failure monitoring: Yes
- Phase regeneration detection: Up to 80% of the average voltage of the other two phases
- Detection settings: Fixed, non-adjustable
- Fault memory: No
- Output operating logic: Positive logic
- Operating temperature: −25 to +55 °C
- Protection rating: IP20
- Mounting type: 35 mm DIN rail
- Terminal type: Screw terminals
- Dimensions (H × W × D): 89.8 × 17.5 × 60.8 mm
- Dielectric strength between supply and contacts: 3000 V
- Impulse withstand voltage between supply and contacts: 5 kV
- Applicable railway standards: EN 50155, EN 61373, EN 45545-2
- EAN: 8012823372938
Reliable Phase Failure and Phase Sequence Monitoring
Three-phase monitoring relays such as the Finder 70.61.8.400.0000T supervise the condition of electrical supply phases to help prevent machinery from operating under unsuitable supply conditions. Incorrect phase sequence can cause three-phase motors to rotate in the wrong direction, while phase failure can lead to abnormal motor operation, increased current in the remaining phases and potential equipment damage. The monitoring relay detects these conditions and provides an output signal that can be used to interrupt an associated control circuit.
The Finder 70.61T uses positive output logic, meaning its normally open output contact closes when the three-phase supply is correct. If the phase sequence is incorrect at power-up, the relay will not energise. When a phase is lost during operation, the relay output releases. The design also supports phase loss detection under regeneration conditions, where a disconnected phase may retain an induced voltage from a running motor. With no fault memory, the relay automatically returns to its normal operating state when acceptable supply conditions are restored. It should be used with correctly selected contactors and protective devices rather than as a replacement for short-circuit or overload protection.
Typical Applications
- Railway electrical equipment and onboard control systems.
- Three-phase motor supply monitoring and protection circuits.
- Industrial machinery and motor control centres.
- Conveyor systems and material handling equipment.
- Pumps, compressors and industrial ventilation systems.
- Hoists, cranes and lifting equipment.
- Electrical distribution panels and automation cabinets.
- Phase sequence verification in industrial installations.
- PLC-controlled alarm and electrical interlocking systems.
- OEM machinery and industrial electrical equipment manufacturing.
