Model 20/21 3-Phase Monitors with Trip and Restart Delays
The Model 20 & 21 are microcontroller-based universal 3-phase monitors for protecting 3-phase motors from abnormal power conditions. They can detect under voltage, over voltage, voltage unbalance, reverse phase, and single-phasing even when regenerated voltage is present. The Model 20 & 21 include adjustable trip and restart delays to prevent nuisance tripping during power fluctuations and short cycling in compressor applications. Both units have LED status indicators and adjustment pots for Voltage Adjustment, % Unbalance, Restart Delay and Trip Delay. The Model 20 & 21 are UL Recognized in the U.S. and Canada.
Automatic or manual restart versions are available. The Model 20 & 21 do not require a neutral connection and can be used on either Wye or Delta systems.
Reset* | Auto or Manual | ||
Operating Voltage | 190-480 VAC | 95-120 VAC | 475-600 VAC |
Frequency | 50/60Hz | ||
Type of Measurement | RMS | ||
Under Voltage Trip Reset |
90% ±1% 93% ±1% | ||
Over Voltage Trip Reset |
110% ±1% 107% ±1% | ||
Voltage Unbalance Trip Reset |
2-8%, adjustable Trip setting minus 0.7% | ||
Trip Delay Time Over, Under, & Unbalanced Single-Phasing Faults Unbalance > 15% |
1-30 sec., adjustable 1 sec., fixed 1 sec., fixed | ||
Restart Delay | 1-500 sec. | ||
Output Contacts | SPDT 10A at 240VAC | ||
Mounting | DIN Rail/Surface Mount or 8-Pin Socket | ||
Agency Approval | UL Recognized (U.S. and Canada) | ||
