Time Mark 279 Data Sheet
AC
SUPPLY
VOLTAGE
DC
POWER
INPUT
SENSING
CIRCUIT
MODEL 279B
-
+
3 4 1
2
8
6
5
M
MOTOR
M
O/L'S
M
shows no power applied
MODEL 279
TIME MARK is a division of
DC Current Monitor
Adjustable Hysteresis and Trip Points
Automatic or Manual Reset
Remote Adjust and Reset Available
5-Year Unconditional Warranty
DESCRIPTION
The Model 279 DC Current Monitor is a single
set-point DC current monitor. It can sense either
1-10 Amps DC (24VAC or 120VAC) or 0.1-1
Amps DC (120VAC).
The standard version, the Model 279B, has a
screwdriver adjustable trip and hysteresis setting
on top of the device. The hysteresis setting
adjusts from 0% to 100%, and can be set fully
clockwise for manual reset operation. A remote
adjust version, the Model 279C, has a remote trip
adjustment and a remote reset button.
The Model 279B plugs into a standard 8-pin
socket, while the Model 279C plugs into a
standard 11-pin socket. An LED indicator is
provided on both versions to indicate when the
relay is energized (i.e. current is above the trip
setting).
TYPICAL APPLICATION - Model 279B
SPECIFICATIONS
Model 279B-24
279C-24
Current range 1-10 Amps 0.1-1 Amps
Supply voltage 24VAC 120VAC 120VAC
Input frequency 50 - 60Hz
Maximum current 15 Amps continuous
Maximum surge current 100A for 100ms
Power consumption 5.3W 2.5W
Transient protection 2500 VRMS for 10ms
Hysteresis adjustment 0% to 100%
Reset Automatic or Manual
Repeat accuracy 1% maximum
Output contacts SPDT 10A at 240VAC resistive
Expected relay life Mech: 10 million operations
Elec: 100,000 operations at rated load
Operating temperature -20° to +131° F
Humidity tolerance 0-97% w/o condensation
Mounting * socket sold separately
Case material ABS plastic
Weight 7.5 oz.
*For 279B units, order 8-pin socket number 51X120
For 279C units, order 11-pin socket number 51X16
279B-120
279C-120
279BA-120
279CA-120
DIMENSIONS
See
diagrams
on
back.
06/2012
© 2012 TIME MARK CORPORATION
DC
POWER
INPUT
AC
SUPPLY
VOLTAGE
SENSING
CIRCUIT
MODEL 279C
+
-
-
-
+
+
3 4 1
2
8
6
5
9
10 7 11
TRIP
ADJUST
RESET
M
MOTOR
M
O/L'S
M
shows no power applied
MODEL 279
TIME MARK is a division of
DC Current Monitor
READ ALL INSTRUCTIONS BEFORE INSTALLING, OPERATING OR SERVICING THIS DEVICE.
KEEP THIS DATA SHEET FOR FUTURE REFERENCE.
GENERAL SAFETY
POTENTIALLY HAZARDOUS VOLTAGES ARE PRESENT AT THE TERMINALS OF THE MODEL 279.
ALL ELECTRICAL POWER SHOULD BE REMOVED WHEN CONNECTING OR DISCONNECTING WIRING.
THIS DEVICE SHOULD BE INSTALLED AND SERVICED BY QUALIFIED PERSONNEL.
Installation Instructions
INSTALLATION
Using the Model 279 DC Current Monitor pin drawings
(contacts shown in the de-energized condition), connect
operating voltage, current input, and load wiring to the
socket Be sure to observe DC current polarity.
The Model 279’s internal relay will energize when the
input current rises above the trip setting. The LED
indicator will illuminate whenever the relay is energized.
Apply the AC supply voltage for a 15 minute warm-up
period before making the trip adjustments.
Note: When installing the Model 279 DC Current Monitor
in areas of high humidity or contamination, the manufacturer
recommends that the base area and all exposed metal parts
of the socket be coated liberally with a good quality silicone
grease, such as Dow Corning DC-4 or DC-4X. Insert the unit
into the socket and wipe off excess grease from around the
base. This will prevent the entrance of moisture and other
contaminants into the base and socket area.
ADJUSTMENT
The Model 279 DC Current Monitor is screwdriver
adjustable. The most accurate calibration is to apply
the current level at which the unit is to trip, then adjust
the relay to be energized.
An alternate method is to turn the trip adjust fully
clockwise and apply normal operating current, at 0%
hysteresis. Adjust the trip adjust counter-clockwise until
the relay just trips, then adjust clockwise until the relay
resets. This results in the Model 279 tripping on
relatively small current changes.
The hysteresis (dead band) adjustment determines at
what current level the Model 279 resets. For example; if
3 amps is applied and the Model 279 is set to trip at 5
amps with a 20% dead band, after tripping the current
must drop at least 1 amp before the Model 279 can
reset.
TYPICAL APPLICATIONS - Model 279C
PIN DIAGRAMS
Model 279B Model 279C
WARRANTY
This product is warranted to be free from defects in materials
and workmanship, and is covered by our exclusive 5-year
Unconditional Warranty. Should this device fail to operate
for any reason, we will repair it for five years from the date of
manufacture. For complete warranty details, see the Terms
and Conditions of Sales page in the front section of the Time
Mark catalog or contact Time Mark at 1-800-862-2875.
© 2012 TIME MARK CORPORATION
06/2012
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