Eaton DT3000 - Functional Description; Installation; Panel Preparation; Mounting the Digitrip 3000 with Dual-Source Power Supply

I.B. 17555C
Effective November 1999
Page B4
3.0 FUNCTIONAL DESCRIPTION
The Dual-Source Power Supply contains 1 ac voltage
transformer and 3 ac current transformers. The ac volt-
age transformer is used to supply nominal ac control
power to the unit. The current transformers are used to
power the unit from the line current. Normally, the unit will
operate from the ac auxiliary power. Since this voltage is
usually obtained from the system containing the circuit
that the relay is protecting, a fault on the protected line
could cause the ac voltage to drop below an acceptable
operating level. Below approximately 70 volts for DT3010
or 140 volts for DT3020, the DSPS switches over to cur-
rent powering. All three current transformer secondaries
are connected in series to supply this power. The DSPS
will supply enough power to operate the Digitrip 3000
overcurrent relay in the tripped state with currents greater
than 1.8 per unit rated secondary current, or 9A, in a sin-
gle-phase. The DSPS will operate with 3-phase currents
in a tripped state with currents greater than 1.2 per unit or
6A rated secondary current.
NOTE: There will be no effect to the DT3000 relay trip
time accuracy when the Dual-Source Power Supply
switches from normal ac voltage to fault-current
power.
4.0 INSTALLATION
NOTE: The following material replaces Paragraph 5-2
on page 34.
4.1 PANEL PREPARATION
The dimensions for the cutout, along with the location of
the 10 mounting holes, are shown in
Figure 5-1 . Before
actually cutting the panel, be sure that the required 3-
dimensional clearances for the relay chassis allow
mounting in the desired location. The Digitrip 3000 with
DSPS dimensions are shown in Figure B-2.
4.2 MOUNTING THE DIGITRIP 3000 WITH DUAL-
SOURCE POWER SUPPLY
Once the cutout has been prepared in the panel or
switchgear enclosure, according to
Figure 5-1 , the Dig-
itrip 3010/3020 can be mounted.
CAUTION
SUPPORT THE PROTECTIVE RELAY FROM THE
FRONT SIDE WHEN MOUNTING. WITHOUT SUCH
SUPPORT, THE PROTECTIVE RELAY COULD FALL
AND CAUSE DAMAGE OR INJURY COULD RESULT.
Do not use a tap on the face of the relay. Use all 10 self-
tapping screws included with the relay to mount the unit
on the panel.