Utility Relay Company AC-PRO-II, Instruction Manual

Page: 22 / 56

AC-PRO-II
®
Instruction Manual www.utilityrelay.com
Page 20
The optional Voltage Divider Module (VDM) provides the
following voltage-based protection and voltage and power
calculations:

Under-Voltage Trip & Alarm (Brown Out)

Over-Voltage Trip & Alarm

Voltage Metering

Power Metering:
(KW, KVA, KWHr, KVAHr, Power Factor)
The VDM is rated for up to 600V three-phase power
systems. In addition, the VDM provides continual power to
the AC-PRO-II when the breaker line side is powered,
allowing the trip unit to communicate breaker status even if
the breaker is open or not carrying sufficient current. For
that reason, the VDM option is recommended if the trip unit
will be incorporated in a communications system to avoid
possibility of intermittent communications.
The VDM mounts directly to the back of the AC-PRO-II and
connects to the trip unit via an internal ribbon cable.
See Figure 5.2 for VDM picture and Figure 5.3 for a diagram.
The SAFE-T-TRIP remote trip device is available for the
AC-PRO-II. The SAFE-T-TRIP allows an operator to trip
open a breaker without standing in front of the breaker. It
also provides a way to obtain the breaker mechanism
operation speed for the important
first operation . This is
accomplished using the patented Sluggish Breaker feature in
the AC-PRO-II.
The SAFE-T-TRIP device is furnished with a permanently
connected 15-foot USB cable, allowing the breaker to be
tripped without standing directly in front of the breaker, thus
reducing the arc flash hazard risk.
The SAFE-T-TRIP device connects directly to the trip unit
Mini-USB port or the door-mounted USB Extender.
The SAFE-T-TRIP device should not be operated while
standing in front of a racked in breaker or breaker cubicle.
The SAFE-T-TRIP is supplied with a 9V lithium battery, the
attached USB cable with magnetic cable wrap (for stress
relief), and Instructions, in a durable, waterproof case.
Figure 9.1: SAFE-T-TRIP
Figure 9.2: SAFE-T-TRIP in case
The AC-PRO-II patented Sluggish Breaker Detection feature
captures the breaker clearing time when a trip occurs that
was initiated by the trip unit. If the breaker clearing time is in
excess of the Sluggish Breaker clearing time setting (see
Section 11.19), an alarm message will appear, and if set, the
alarm relay will operate.
If a “sluggish” trip occurs, breaker mechanism maintenance
is required.
When the AC-PRO-II sends a trip pulse to the breaker
actuator, the Sluggish Breaker timer starts. The trip unit
determines the breaker clearing time by one of two methods:
1) Zero Current Method: If an auxiliary breaker
position contact is NOT wired into the trip unit, the
breaker position contact user setting should be set
to “OFF”, and the trip unit will record the breaker
clearing time by monitoring the current values.
The Sluggish Breaker timer stops when the
current is zero. This method records the breaker
clearing time for each breaker pole.
**** NOTE ****
When using the zero current method, the Sluggish
Breaker feature requires the pre-trip primary
current to be 10% of the CT rating or greater.
2) URC Breaker Positition Switch Method: If a
breaker position contact is wired into the trip unit,
the breaker position contact user setting should
set to “52a” or “52b”, and the trip unit will record
the breaker clearing time based on the change in
state of the auxiliary breaker contact. The
Sluggish Breaker timer stops when the contact
changes state. This method records one breaker
clearing time and reports the same value for each
pole.
**** NOTE ****
The Sluggish Breaker feature does not work with
Secondary Injection Test sets.
Additionally, the breaker clearing time can be considered
when performing Arc Flash Studies. Any modifications of
clearing times used in Arc Flash Studies should be
performed by a qualified engineer.
8.0 Voltage Divider Module (VDM) (optional)
9.0 SAFE-T-TRIP
TM
(optional)
10.0 Sluggish Breaker
TM
Detection