Protection Relays
Voltage Monitoring Relays
DLMU SERIES
Description
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.
Operation
Upon application of line voltage, the output is de-energized
and the restart delay begins. If all the 3-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 undervoltage trip points
are set automatically. 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.
Wiring Diagram
!
L1, L2, L3 = Line Voltage Input
NO = Normally Open Contact
NC = Normally Closed Contact
C = Common, Transfer Contact
CAUTION:
2 amp max. fast acting fuses are
recommended to protect the equipment‘s wiring.
They are not required to protect the DLMU.
! = Select alarm contact connection as N.O. or N.C. when ordering;
N.O. Shown.
Features & Benefits
FEATURES
Proprietary
microcontroller
based circuitry
Universal line
voltage range
DIN rail (35mm) or
surface mounting
LED indication
User adjustable
time delays
BENEFITS
Constant monitoring to protect against phase loss,
phase reversal, over voltage, under voltage,
unbalance, short cycling and over/under frequency
Flexibility to work in 200 to 480VAC or 500 to
600VAC applications
Installation flexibility
Provides diagnostics of relay, fault and time
delay status
Prevents nuisance tripping and short cycling of
sensitive equipment
Ordering Information
MODEL
LINE VOLTAGE
OUTPUT
RESTART FUNCTION
VOLTAGE UNBALANCE
TRIP DELAY
RESTART DELAY
DLMHBRAAA
DLMUBLAAA
DLMUBNAAN
DLMUBRAAA
500 to 600VAC
200 to 480VAC
200 to 480VAC
200 to 480VAC
SPDT & NO
SPDT & NO
SPDT & NO
SPDT & NO
Staggered restart
Lockout, min off time
No restart delay
Staggered restart
Adjustable 2 - 10%
Adjustable 2 - 10%
Adjustable 2 - 10%
Adjustable 2 - 10%
Adjustable 1 - 30s
Adjustable 1 - 30s
Adjustable 1 - 30s
Adjustable 1 - 30s
Adjustable 0.6 - 300S
Adjustable 0.6 - 300S
None
Adjustable 0.6 - 300S
If you don’t find the part you need, call us for a custom product 800-843-8848
© 2016 Littelfuse Protection Relays & Controls
www.littelfuse.com/dlmu
www.littelfuse.com/
Rev: 1-A-062716
Protection Relays
Voltage Monitoring Relays
DLMU SERIES
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.
Undervoltage & Voltage
Unbalance
Type
Overvoltage
TripVoltage
Reset Voltage
Undervoltage
Trip Voltage
Reset Voltage
Voltage Unbalance
Reset on balance
Trip Delay
Active On
Range
Tolerance
Restart Delay
Range
Tolerance
Over/Under Frequency
Phase Sequence
Response Time -Phase
Reversal & Phase Loss
Reset
Output
Type
Form C
Form C Rating
Voltage detection with delayed trip &
automatic reset
109 - 113% of the adjusted line voltage
≅
-3% of the trip voltage
88 - 92% of the adjusted line voltage
≅
+3% of the trip voltage
Adjustable 2 - 10% or specify fixed unbalance
of 2 - 10% in 1% increments
≅
-0.7% unbalance
Over/undervoltage, voltage unbalance, over/
under frequency
Adjustable from 1 - 30s or specify fixed delay
1 - 30s in 1s increments
± 15%
Adjustable from 0.6 - 300s; if no restart delay
is selected a 0.6s initialization delay applies
± 15%
±4%; Reset ±3%; 50/60 Hz
A, B, C, L1, L2, L3
≤200 ms
Automatic
Isolated Electromechanical Relay
Isolated, SPDT
10A resistive @ 240VAC;
8A resistive @ 277VAC; NO-1/4 hp @ 120VAC;
1/3 hp @ 240VAC
Isolated, NO, SPST
2A @ 277VAC
Mechanical - 1 x 10
6
; Electrical - 1 x 30
3
ASME A17.1 Rule 210.6
NEMA MG1 14:30, 14:35
IEEE C62.41-1991 Level B
≥ 2500V RMS input to output
Surface mount with 2 #8 (M4 x 0.7) screw or
snap on 35mm DIN Rail
Note: 0.25 in.(6.35 mm) spacing between
units or other devices is required
H
110 mm (4.33”);
W
75 mm (2.95”);
D
50 mm (1.97”)
Screw terminals with captive wire clamps for
up to #14 AWG (2.5 mm
2
) wire
4.4 in.-lbs.
Accessories
LPSM003ZXID (Indicating),
LPSM003Z (Non-indicating) Fuse Holders
Littelfuse POWR-SAFE Dead Front holders
provide optimum protection to personnel for
Class CC and Midget-Style fuses. 600 VAC/DC
0KLK002.T Midget Fuse (2 Amp)
10 x 38 fast acting, high-interrupting capacity,
current-limiting type fuse. 600 Vac/500 Vdc
C103PM (AL) DIN Rail
35 mm aluminum DIN rail available in a 36 in.
(91.4 cm) length.
Form A
Form A Rating
Life
Protection
Phase Reversal/Failure
Motors and Generators
Surge
Isolation Voltage
Mechanical
Mounting
Specifications
Line Voltage
Type
Operating Voltage
200-480VAC
3-phase delta or wye with no connection
to neutral
Range
Voltage
Adj.Range
Line
Line Voltage
Frequency
Max.
Dimensions
Termination
Terminal Torque
Environmental
Operating/Storage
Temperature
Humidity
Weight
600VAC
240
380
480
600
200-240VAC
340-420VAC
400-480VAC
500-600VAC
50/60Hz
50Hz
60Hz
50/60Hz
550VAC
600VAC
AC Line Frequency
Phase Loss
Response Time
50/60 Hz automatically detected
≥ 25% unbalance
≤200ms
-40° to 60°C / -40° to 85°C
95% relative, non-condensing
≅
8.6 oz (244 g)
© 2016 Littelfuse Protection Relays & Controls
www.littelfuse.com/dlmu
www.littelfuse.com/
Rev: 1-A-062716
Microcontroller MCU
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