21L
The Model 21-L 3-Phase Monitor provides essential protection for industrial equipment operating on 95-120 VAC systems. This auto-reset unit continuously monitors for critical conditions including phase loss, phase reversal, over/under voltage, and voltage unbalance. Its comprehensive detection capabilities help prevent costly damage and downtime in three-phase applications. Users can adjust trip delays from 1-30 seconds and restart delays from 1-500 seconds, allowing for precise system integration. The monitor features SPDT 10A output contacts for reliable control. Designed for demanding environments, it operates effectively from -20° to +140° F with 0-97% humidity tolerance. This device ensures consistent operational integrity and extends equipment lifespan by proactively addressing power anomalies. Its robust design and UL recognition underscore its suitability for diverse industrial control panels, offering a dependable solution for power quality management.
The Model 21 is a microcontroller-based universal 3-phase monitor for
protecting 3-phase motors from abnormal power conditions. It can detect
under voltage, over voltage, voltage unbalance, reverse phase, and
single-phasing even when regenerated voltage is present. The Model 21
includes adjustable trip and restart delays to prevent nuisance tripping
during power fluctuations and short cycling in compressor applications.
The LED status indicators and adjustment pots for Voltage Adjustment, %
Unbalance, Restart Delay and Trip Delay are mounted on the front of the
unit for easy access. Automatic or manual restart versions are
available. The Model 21 does not require a neutral connection and can be
used on either Wye or Delta systems. All versions of the Model 21 are
available with optional gold flashed silver contacts for low current applications..
Out of stock
Specifications
| Model Type | Auto Reset |
|---|---|
| Operating Voltage | 95-120 VAC |
| Power Consumption | 3.7W at 120V |
| Auto Ranges | No |
| Monitored Conditions | Phase Loss, Phase Reversal, Over/Under Voltage and Voltage Unbalance |
| Frequency | 50/60Hz |
| Type of Measurement | RMS |
| Under Voltage Trip | 90% ±1% (% of setpoint) |
| Under Voltage Reset | 93% ±1% (% of setpoint) |
| Over Voltage Trip | 110% ±1% (% of setpoint) |
| Over Voltage Reset | 107% ±1% (% of setpoint) |
| Voltage Unbalance Trip | 2-8%, adjustable (conforms to NEMA) |
| Voltage Unbalance Reset | Trip setting minus 0.7% |
| Trip Delay Time (Over, Under, & Unbalanced) | 1-30 sec., adjustable |
| Trip Delay Time (Single-Phasing Faults Unbalance > 15%) | 1 sec., fixed |
| Trip Delay Time (Reverse Phase) | 1 sec., fixed |
| Restart Delay | 1-500 sec., adjustable |
| Manual Reset Input | 5V open circuit/500µA short circuit |
| Output Contacts | SPDT 10A at 240VAC resistive |
| Operating Temperature | -20° to +140° F |
| Humidity Tolerance | 0-97% w/o condensation |
| Enclosure Material | Noryl plastic |
| Mounting | 8-Pin Socket (**sold separately) |
| Recommended Socket | 51x120 |
| Additional Options | /SG = Silver with Gold Flash Contacts |
| Agency Approval | UL Recognized (U.S. and Canada) (For use in a Pollution Degree 2 Environment) |
| Neutral Connection | Not required |
| System Compatibility | Wye or Delta systems |
| Recommended Fuse | 1A 600VAC |
| Warranty | 5-year Unconditional Warranty |
