NewTrend · three-phase monitoring relay
Product overview
NewTrend RV8-21 provides phase sequence, phase failure monitoring for three-phase control circuits. The selector combines three-wire/four-wire system choice with phase-sequence ON/OFF. The 18mm DIN-rail relay provides 2 SPDT contacts rated 8A (AC-1). Its phase-sequence protection can be enabled or disabled.
Technical selection summary
| Model | RV8-21 |
|---|---|
| Functions | Phase sequence + phase failure |
| Voltage-system selection | 3P3W or 3P4W on the front selector |
| Three-wire nominal voltage | 380 / 400 / 415 / 440 / 480V, phase-to-phase |
| Four-wire nominal voltage | 220 / 230 / 240 / 254 / 277V, phase-to-neutral |
| 3P3W / 3P4W monitoring terminals | L1-L2-L3 / L1-L2-L3-N |
| Supply terminals | L1-L2 |
| Frequency / measurement | 45-65Hz; true RMS |
| 3P3W / 3P4W measuring ranges | 260-576V / 150-332V |
| Measurement error | Maximum 1% |
| Overvoltage / undervoltage | Not provided by this function code |
| Asymmetry protection | Not provided by this function code |
| Trip delay | No adjustable delay specified for code 21 |
| Phase-sequence protection | ON / OFF selectable |
| Power-up delay / reset time | 0.5s / 1s |
| Output contacts / rating | 2 SPDT / 8A (AC-1) |
| Switching voltage / minimum DC power | 250VAC / 24VDC; 500mW |
| Output / fault indication | Green LED / red LED |
| Mechanical / electrical life (AC-1) | 10,000,000 / 100,000 operations |
| Temperature coefficient | 0.05%/degree C at 20 degrees C |
| Operating / storage temperature | -20 to +55 / -35 to +75 degrees C |
| Mounting / operating position | DIN rail to EN/IEC 60715; any position |
| Protection | IP40 front panel; IP20 terminals |
| Overvoltage category / pollution degree | III / 2 |
| Maximum conductor size | Solid: 1 x 2.5mm2 or 2 x 1.5mm2; with sleeve: 1 x 2.5mm2 (AWG 12) |
| Tightening torque | 0.4Nm |
| Body dimensions | 90 x 18 x 64mm |
| Weight | 69-72g by version |
| Referenced standards | EN 60255-1; IEC 60947-5-1 |
Operation
- The selector combines three-wire/four-wire system choice with phase-sequence ON/OFF.
- The green LED indicates relay-output state and the red LED indicates a fault. Loss of a supply phase at L1 or L2 can extinguish indication; do not interpret an unlit LED as proof that the circuit is safe.
Typical applications
- Phase supervision in motor contactor-control circuits
- Three-phase industrial control panels
View or download RV8-21 to RV8-26 catalogue (PDF)
Product reference images and drawings
RV8-21 to RV8-26 – selection and technical specifications
RV8-21 to RV8-26 – wiring, dimensions and operation
Set the phase-sequence/system selector for the actual three-wire or four-wire installation and required phase-sequence protection. Isolate before changing wiring. Installation and wiring must be performed by qualified electricians.
