DLMUBNAAN - DLM Series

Series: DLM
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Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

The DLMU Series is a universal voltage, 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, SPDT and 2A alarm output 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.

Property (Mouseover for details) Value
Input Voltage (V) 200 - 480 Vac
Input Voltage Maximum (V) 550
Input Type 3-phase delta or WYE with no connection to neutral
Input AC Line Frequency (Hz) 240 V ac: 50/60; 380 V ac: 50; 480 V ac: 60
Input Phase Sequence A; B; C; L1; L2; L3
Output Type Isolated electromechanical relay
Output Load Rating (VA) 10 A resistive @ 240 Vac; 8 A resistive @ 277 Vac; NO-1/4 hp @ 120 Vac; 1/3 hp @ 240 Vac
Reset Time (ms) Automatic
Response Time (ms) Phase loss: ≤200 ms; Phase reversal: ≤200 ms
Restart Delay Range No restart delay; 0.6 s initialization delay applies
Restart Delay Tolerance (%) ±15%
Trip Delay Type Active On: Over/undervoltage; voltage unbalance; over/under frequency
Trip Delay Range 1-30 s adjustable
Trip Delay Tolerance (%) ±15%
Overvoltage Trip Voltage (%) 109 - 113% of the adjusted line voltage
Overvoltage Reset Voltage (%) ≅-3% of the trip voltage
Undervoltage Trip Voltage 88 - 92% of the adjusted line voltage
Undervoltage Reset Voltage (%) ≅+3% of the trip voltage
Voltage Unbalance Trip Point (%) Adjustable 2 - 10%
Voltage Unbalance Reset (%) ≅-0.7% unbalance
Over/Under Frequency (%) ±4%; Reset ±3%; 50 / 60 Hz
Phase Loss ≥25%
Isolation Voltage (V) ≥2500 Vrms input to output
Surge Protection IEEE C62.41-1991 Level B
Type of Detection Voltage detection with delayed trip and automatic reset
Termination Type Screw terminal with captive wire clamps for up to #14 AWG (2.5 mm²) wire
Mounting Method Surface mount with two #8 (M4 x 0.7) screws or snap on 35mm DIN rail
Operating Temperature -40° to 60°C (-40° to 140°F)
Storage Temperature (F/C) -40° to 85°C (-40° to 185°F)
Humidity 95% non-condensing
Dimensions 4.33 H x 2.95 W x 1.97 D in. (110 x 75 x 50 mm)
Weight (lbs/g) 0 Kg
Check Stock Yes
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