The RT-818 monitors three-phase symmetrical supply voltage for drop and phase sequence faults. The permissible voltage variation limit is internally preset at -18% for asymmetric drop and -12% for symmetrical drop. It operates independently of the neutral conductor, making it suitable for symmetrical load circuits. The unit connects via an 8-pin lamp base and is compatible with 380VAC ±10% at 50/60 Hz.

Output is via an 8A SDTP relay with SPDT AC1 10A/250VAC contacts. Indicator lamps show supply voltage presence and out-of-limits or reverse phase-sequence conditions. Fall time and reset time are both preset at under 0.5 seconds, with a release delay of 40ms.

Key Features

• Three-phase voltage monitoring — supervises drop and phase-sequence faults
• Neutral-independent operation — works on symmetrical load circuits without neutral
• 18% voltage drop limit — internally preset, no external calibration required
• Phase failure (Pf) and phase sequence (Ps) monitoring functions
• 8-pin lamp-base connection — plug-in installation into a standard relay socket
• Supply voltage and fault indicator lamps

Product Benefits

• Preset limits mean the unit is operational immediately after installation
• Fall time under 0.5 seconds and release delay of 40ms give fast fault response
• SPDT 10A/250VAC output contacts connect directly to contactors and motor starters
• IP20 enclosure suits standard industrial panel mounting
• Symmetrical-drop threshold at 12% catches gradual voltage degradation before equipment damage

Technical Specifications

• Model: RT-818
• Power Supply: 380VAC ±10%, 50/60Hz
• Permissible Voltage Variation: -18%
• Symmetrical Drop Threshold: -12%
• Output Relay: 8A SDTP
• Output Contacts: SPDT AC1 10A/250VAC
• Fall Time: <0.5 sec (preset)
• Reset Time: <0.5 sec (preset)
• Release Delay: 40ms
• Connection Type: 8-pin lamp base
• Degree of Protection: IP20
• Voltage Type: AC
• Functions: Phase Failure (Pf), Phase Sequence (Ps)

Why You'll Love It

• 8-pin plug-in base allows fast replacement without rewiring the panel
• Visual indicators give at-a-glance status without opening the panel door
• Neutral-independent design simplifies installation in delta and symmetrical circuits
• Package includes 1× Voltage Monitor Three-Phase RT-818 380VAC 8-Pin