Medium Voltage Application Guide

Incomer feeder
panel
Transformer
Motor
Power factor
bank
SWITCHGEAR
ANSI
code
Function Description Application Components
required
CT VT
67 AC directional
current relay
79 AC reclosing
relay
Activates when the current, flowing in a
specific direction, exceeds a preset level.
This protection is based on 50 and 51
functions.
Controls the automatic reclosing and
locking-out of an AC circuit switching
device.
81 Frequency relay Activates if the frequency falls outside a
preset range.
86 Locking-out Shuts down or holds equipment out of
relay
service under abnormal conditions. May
be manually or electrically operated.
87 (L,
T, M)
Differential
protection relay
Activates if the detected current on
opposite sides of a machine or
transformer are not equal to each other.
(L = line, T = transformer,
G = generator)
X
X
X
X
X X X X
X X X
AuCom soft starter ANSI protection functions
The following ANSI code protections are standard in AuCom medium voltage soft starters. For details of additional
protections in MVS and MVX which are not listed in this table, refer to the relevant user manual.
ANSI ANSI Function
MVS/MVX Trip
Code
26 Apparatus device Motor thermal model
27/59 Under/overvoltage relay Undervoltage and overvoltage
37 Undercurrent/power relay Undercurrent
46 Phase reversal or current imbalance relay Phase sequence and current imbalance
48 Incomplete sequence relay Excess start time
50 AC instantaneous or di/dt relay Instantaneous overcurrent
51 AC time-overcurrent relay Time-overcurrent
64 Ground (earth) detector relay Ground fault
81 Frequency relay Supply frequency
Temperature related protection functions such as motor winding and bearing protection require a separate
protection device which can be installed in the LV section of the soft starter panel.
Page 126 Medium Voltage Application Guide 710-12280-00A