NewTrend · Star-delta timer relay
Product overview
NewTrend RT8-ST provides a timed star-to-delta starting sequence for motor control. Set the star interval t1 from 0.1 seconds to 10 minutes, followed by a separately adjustable 0.1-1 second transfer interval t2. Two SPDT outputs operate the star and delta contactor circuits in an 18mm DIN-rail housing.
Technical selection summary
| Model | RT8-ST |
|---|---|
| Output contacts | 2 SPDT |
| AC power input | AC maximum 6VA / 1.3W |
| Weight | W240: 82g; A230: 80g |
| Function | Star-delta motor starting sequence |
| Supply terminals | A1-A2 |
| Control supply options | W240: AC/DC 12-240V; A230: AC 230V; A400: AC 400V; 50-60Hz |
| Supply tolerance | -15% to +10% |
| W240 burden | AC 0.3-2VA / DC 0.1-1.2W |
| Supply indication | Green LED |
| Time setting | Range switch and potentiometers |
| Timing range | Star time t1: 0.1s-10min; transfer interval t2: 0.1-1s |
| Marked time ranges | t1: 1s, 10s, 1min, 10min; t2: 0.1-1s |
| Time setting deviation | 10% with mechanical adjustment |
| Repeat accuracy | 0.2% of set value |
| Temperature coefficient | 0.05%/degree C at 20 degrees C |
| Contact rating | 16A (AC-1) |
| Switching voltage | 250VAC / 24VDC |
| Minimum DC breaking power | 500mW |
| Output indication | Red LED |
| Mechanical life | 10,000,000 operations |
| Electrical life (AC-1) | 100,000 operations |
| Reset time | Maximum 200ms |
| Operating temperature | -20 to +55 degrees C |
| Storage temperature | -35 to +75 degrees C |
| Mounting | DIN rail to EN/IEC 60715 |
| Protection | IP40 front panel; IP20 terminals |
| Operating position | Any |
| Overvoltage category | III |
| Pollution degree | 2 |
| Maximum conductor size | Solid: 1 x 2.5mm2 or 2 x 1.5mm2; with sleeve: 1 x 2.5mm2 (AWG 12) |
| Terminal tightening torque | 0.4Nm |
| Body dimensions | 90 x 18 x 64mm |
| Referenced standards | EN 61812-1; IEC 60947-5-1 |
Set the star interval with its marked range and 10%-100% fine adjustment. Set the transfer interval independently from 0.1 to 1 second. Use suitable contactors and the required electrical/mechanical interlocking for the motor starter.
Operation
- After the supply is applied, output 15-18 operates for the selected star interval t1. After it releases, the transfer interval t2 runs before output 25-28 operates for delta.
Typical applications
- Star-delta motor starting
- Contactor sequencing in motor starter panels
Specify your enquiry
For a focused quotation, include:
- Required control-supply version
- Timing intervals, load type and required operating sequence
- Quantity, delivery destination and documentation requirements
Download NewTrend RT8-ST datasheet (PDF)
Product reference images and drawings
Relay terminal connections
Star-delta timing diagram
Dimensions in millimetres
Star-delta starter reference circuit
Set the star interval with its marked range and 10%-100% fine adjustment. Set the transfer interval independently from 0.1 to 1 second. Use suitable contactors and the required electrical/mechanical interlocking for the motor starter. Installation and wiring must be performed by qualified electricians.
