Wednesday, July 4, 2018

SSAC/Littelfuse Voltage Monitor HLMUDLAAA

Voltage Monitor Protection Relay HLMUDLAAA from Anderson-Bolds
Made by Littelfuse

Contact Anderson-Bolds

LittelFuse SSAC Voltage Monitor HLMUDLAAA is a universal voltage monitor. 10 amp output relay rating. The HLM Voltage Monitor senses over or under voltage AND phase unbalance and frequency fluctuations and trips if any go oout of range. The Voltage Monitors are currently made by Little Fuse. UL, CSA and CE. Previous manufacturers were SSAC, Entrelac, ABB and Sycom.


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.

Voltage Monitor HLMUDLAAA

Constant monitoring to protect against phase loss, phase reversal; over, under, and unbalanced voltage; over and under frequency
Flexibility to work in 200 to 480VAC applications
Installation flexibility
Provides diagnostics of relay, fault and time delay status
Protects against shock, vibration, and humidity Meets IEC 61000 safety requirements

Upon application of line voltage, the output is de-energized
and the restart delay begins. If all the three-phase voltages are within the acceptable range, the output energizes at the end
of the restart delay. The microcontroller circuitry automatically senses the voltage range, and selects the correct operating frequency (50 or 60Hz). The over and under voltage trip points are set at ± 10% of the adjusted line voltage. When the measured value of any phase voltage exceeds the acceptable range limits (lower or upper) the trip delay begins. At the end of the trip delay the output relay de-energizes. If the phase voltage returns to an acceptable value before the trip delay expires, the trip delay is reset and the output remains energized. Under, over, and unbalanced voltages plus over or under frequency must be sensed for the complete trip delay before the unit trips. The unit trips in 200ms when phase loss or reversal are sensed. The unit will not energize if a fault is sensed as the line voltage is applied. 

Reset: Reset is automatic upon correction of the voltage or frequency fault or phase sequence.

Restart Delay Options
L = Lockout or minimum OFF time. The restart delay begins when the output trips. The unit cannot be re-energized until the restart delay is complete. This provides a minimum off time
or lockout time to allow equipment sensitive to short cycling, time to reset. If the fault is corrected after the restart delay is complete, the output energizes immediately. The restart delay also occurs when line voltage is applied/reapplied.
R = Restart Delay on fault correction. The restart delay begins when line voltage is reapplied or when a voltage fault is corrected. This option is normally selected when staggered restarting of multiple motors on a power system is required.
N = No Restart Delay. 0.6 second initialization delay on application of line voltage applies.
Restart Notes: All restart options remain reset when the following conditions are detected:
1. Phase loss (phase unbalance greater than 25%) 2. Average line voltage less than 120VAC
3. Phase reversal

The restart delay begins when the condition is corrected.

LED Operation
The LED flashes green during the restart delay, then glows green when the output energizes. It flashes red during the trip delay then glows red when the output de-energizes. It flashes red/green if phase reversal is sensed. If a fault is sensed during the restart delay, the LED will glow red during that portion or the full restart delay. 


3-phase delta or wye with no connection to neutral

240 380 480
Voltage Adj. Range
200-240VAC 340-420VAC 400-480VAC
50 or 60Hz 50Hz 60Hz

Line Voltage Max.
AC Line Frequency
50/60 Hz automatically detected
Phase Loss
≥ 25% unbalance
Response Time

Overvoltage Trip Voltage 
109 - 113% of the adjusted line voltage
 Reset Voltage
-3% of the trip voltage

Undervoltage Trip Voltage
88 - 92% of the adjusted line voltage
Reset Voltage
+3% of the trip voltage 

Voltage Unbalance Trip Setpoint
Adjustable 2 - 10% or specify fixed unbalance of 2 - 10% in 1% increments
Reset on Balance
-0.7% unbalance
Trip Delay Active On
Over/under voltage, voltage unbalance, over/under frequency

Adjustable from 1 - 30s or specify fixed delay 1 - 30s in 1s increments
Restart Delay Range
Adjustable from 0.6 - 300s; if no restart delay is selected a 0.6s initialization delay applies 


Over/Under Frequency
±4%; Reset ±3%; 50/60 Hz
Phase Sequence
A, B, C, L1, L2, L3
Response Time-Phase
Reversal & Phase Loss
≤200 ms


Isolated Electromechanical Relay


10A resistive @ 240VAC;
8A resistive @ 277VAC; NO-1/4 hp @ 120VAC; 1/3 hp @ 240VAC

Phase Reversal/Failure

ASME A17.1 Rule 210.6
Motors and Generators
NEMA MG1 14:30, 14:35
IEEE C62.41-1991 Level B
Isolation Voltage
≥ 2500V RMS input to output

H 76.7 mm (3.0”); W 50.8 mm (2.0”);
D 41.7 mm (1.64”)

Screw terminal connection up to 12 AWG (3.3 mm2) wire
 -40° to 60°C / -40° to 85°C


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