21HM
The Model 21-HM 3-Phase Monitor offers robust protection for industrial systems. Operating across a 475-600 VAC range, this manual reset unit detects critical anomalies including phase loss, phase reversal, over/under voltage, and voltage unbalance. Its adjustable trip delay times, from 1 to 30 seconds, allow for precise system integration and fault response customization. The monitor's ability to conform to NEMA standards for voltage unbalance ensures reliable operation in demanding environments. With SPDT 10A at 240VAC resistive output contacts, it provides dependable control. The 21-HM is designed for consistent performance, supported by a 5-year unconditional warranty, ensuring long-term operational stability. Its compact dimensions (2.98" L x 1.77" W x 2.45" H) facilitate installation in various panels, and it does not require a neutral connection.
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 | Manual Reset |
|---|---|
| Operating Voltage | 475-600 VAC |
| Power Consumption | 4.5W at 600V |
| 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 |
