Model 21-L 3-Phase Monitor (Auto Reset, 95-120 VAC)
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.
Universal 3Ph Monitor
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 |
