The HLMU Series is a universal voltage, encapsulated, 3-phase voltage monitor that detects phase loss, reversal, over/under voltage, voltage unbalance, and over/under frequency. It features isolated, 10A DPDT relay contacts, adjustable trip delays from 1 to 30 seconds, and a 0.6-second initialization delay. The HLMUDNAAN variant has fixed voltage unbalance at 4%, a fixed trip delay of 5 seconds, and no restart delay, automatically resetting upon fault correction. It operates on 200-480VAC, supports delta or wye configurations without neutral connection, and mounts via surface mounting or 35mm DIN rail. Dimensions are 76.7 mm H × 50.8 mm W × 41.7 mm D, and it meets IEC 61000 safety requirements, ASME A17.1 Rule 210.6, NEMA MG1 14:30, 14:35, and IEEE C62.41-1991 Level B. The unit has encapsulated circuitry, finger-safe terminal blocks, and ≥2500V RMS input-to-output isolation.
The HLMU Series is a universal voltage, encapsulated, 3-phase voltage monitor. It continuously measures the voltage of each of the three phases with microcontroller accuracy and compares the value to preset trip points. It separately senses phase reversal and loss; over, under and unbalanced voltages; and over or under frequency. Protection is assured during periods of large average voltage fluctuations, or when regenerated voltages are present. The unit trips within 200ms when phase loss is detected. Adjustable time delays are included to prevent nuisance tripping and short cycling of sensitive equipment. The isolated, 10A, DPDT relay contacts trip when a phase voltage exceeds the trip limits for the trip delay. Nominal line voltage, voltage unbalance, and time delays are knob adjustable. The phase loss setpoint and the acceptable frequency range are fixed. Both delta and wye systems can be monitored; no connection to neutral is required. See datasheet for operation details.
Voltage Asymmetry, Voltage Sensing AC, Phase Loss
| Littelfuse, Inc. | Quarktwin Technology Ltd. | |
|---|---|---|
| Product Category | Electromechanical Relays | Protective Relays and Monitoring Relays |
| Product Number | HLMUDNAAN | HLMUDNAAN |
| Product Name | HLM Series – Voltage Monitor | Monitor - Relay Output |
| Mounting | Surface mount with one #10 (M5 x 0.7) screw |
