Time Mark 20AB Data Sheet

MODEL 20AB

TIME MARK is a division of

3-Phase Monitor

with Adjustable Trip & Restart Delays

⚫ Monitors for Phase Loss, Phase Reversal,

Over/Under Voltage and Voltage Unbalance

⚫ Isolated Contacts (1x N.O. & 1x N.C.)
⚫ LED Status Indicators
⚫ DIN Rail or Surface Mount

DESCRIPTION

The Model 20AB is a microcontroller-based universal 3-phase
monitor for protecting 3-phase motors from abnormal power

conditions. It can detect under voltage, over voltage, voltage

unbalance, reverse phase, and single-phasing even when

regenerated voltage is present. The Model 20AB includes
adjustable trip and restart delays to prevent nuisance tripping
during power fluctuations and short cycling in compressor
applications. The LED status indicators and adjustment pots
for Voltage Adjustment, % Unbalance, Restart Delay and Trip
Delay are mounted on the front of the unit for easy access.
The 20AB has 1 normally open (N.O.) & 1 normally closed

(N.C.) isolated contacts.

Automatic or manual restart versions are available. The
Model 20AB does not require a neutral connection and can be

used on either Wye or Delta systems.

All versions of the Model 20AB are available with optional gold

flashed silver contacts for low current applications.

DIMENSIONS

SPECIFICATIONS

Auto Reset Models
Manual Reset Models*

Operating Voltage 190-480 VAC 95-120 VAC 475-600 VAC
Power Consumption 3.7W at 480V 3.7W at 120V 4.5W at 600V
Auto Ranges Yes No
Frequency 50/60Hz
Type of Measurement RMS
Under Voltage

Trip
Reset

Over Voltage

Trip
Reset

Voltage Unbalance

Trip
Reset

Trip Delay Time

Over, Under, & Unbalanced
Single-Phasing Faults

Unbalance > 15%
Restart Delay 1-500 sec., adjustable
Manual Reset Input 5V open circuit/500µA short circuit
Output Contacts 1x N.C., 1x N.O. 7.5A at 240VAC resistive
Operating Temp - 20º to +140º F
Humidity Tolerance 0-97% w/o condensation
Terminal Torque 3.5 in. lbs. maximum
Wire Type Stranded or solid 14-26 AWG, 1/terminal
Enclosure Noryl plastic
Mounting DIN Rail or Surface Mount
Weight 11 oz.
Low Current Options Models ordered with suffix “/SG”

Agency Approval UL Recognized (U.S. and Canada)

* External N.O. momentary pushbutton required for manual reset.

20AB

20AB-M

have silver with gold flash contacts

(For use in a Pollution Degree 2 Environment)

20AB-L

20AB-LM

(% of setpoint)

90% ±1%
93% ±1%

(% of setpoint)

110% ±1%
107% ±1%

(conforms to NEMA)

2-8%, adjustable

Trip setting minus 0.7%

1-30 sec., adjustable

1 sec., fixed
1 sec., fixed

20AB-HM

20AB-H

11440 Ea s t P i ne S t r e e t

Tul s a , Okl a h o m a 7 4 1 1 6

02/2019

© 2019 TIME MARK CORPORATION

MODEL 20AB

TIME MARK is a division of

Universal 3-Phase 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 20AB.

ALL ELECTRICAL POWER SHOULD BE REMOVED WHEN CONNECTING OR DISCONNECTING WIRING.

THIS DEVICE SHOULD BE INSTALLED AND SERVICED BY QUALIFIED PERSONNEL.

Installation Instructions

INSTALLATION

Mount the Model 20AB in a suitable enclosure either to the
back panel of the enclosure using two #6 x 9/16" screws (not

included) or to a DIN rail.

Connect terminals A, B, and C to the line side of the motor
starter. Connect the output relay to the control circuit. When
using manual reset versions either connect a N.O. momentary
switch to the manual reset input for manual reset operation or
jumper the manual reset input for automatic reset operation.

Refer to wiring diagram for example of typical application.

OPERATION (Cont’d)

Manual Reset Versions

When operating in manual reset mode the restart delay is
disabled and the monitor must always be reset manually after
applying power. Both status lights will blink in unison upon
applying power if the monitor was not in the tripped state prior

to a loss of power.

If a fault condition is detected and the monitor trips, the relay

will remain de-energized until the fault condition clears and

the reset switch is pushed. If the monitor remains in the
tripped state when a loss of power occurs, the fault causing

the trip will be displayed on power up.

Automatic and Manual Reset Versions

The status of the 3-phase system is indicated by the red and
green LEDs as follows:

OPERATION

Set the VOLTAGE adjustment to the nominal operating

voltage. Models 20AB and 20AB-M will auto-range to either
the 190-240VAC or 380-480VAC scale. Set the UNBALANCE,

RESTART, and TRIP adjustments as required for the

application.

Automatic Reset Versions

The relay contacts will transfer after applying correct voltage
and phase rotation for the length of the restart delay. The
green LED will blink during the restart delay and will then

remain on indicating the relay contacts have transferred.

TROUBLESHOOTING

Should the Model 20AB Monitor fail to operate properly, check
that all three voltages are present, and are of the correct
voltage level and phase rotation (a Model 108A or 108B
Phase Sequence Detector should be used to verify phase
rotation). Check all fuses and verify that all wiring connections
are correct. If problems persist, contact your local Time Mark

Distributor, or the factory for assistance (Monday-Friday, 8
a.m. to 5 p.m. CST).

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.

11440 Ea s t P i ne S t r e e t

Tul s a , Okl a h o m a 7 4 1 1 6

© 2019 TIME MARK CORPORATION

02/2019