Sensia INSTRUCT ESP Configuration Manual page 10

ESP Switchboard Configuration via ESP Controller
PARAMETERS
Stall
Short Circuit
Motor Amps
Power Factor
The results of these measurements can be combined with the voltage inputs to determine the system power
and power factor.
The CT inputs are located on terminals CT-A, CT-B, CT-C, CT-REF, and CT-SHIELD (PIN 32 - 36).
TERM
CT-A, B, C
CT-REF
CT_SHIELD
Potential Severity: Serious
Potential Loss: Assets, Information
Hazard Category: Electrical
These inputs are designed for the burden module only. Do not directly connect the CT
WARNING leads to the controller.
The CT inputs can be scaled to match external CTs and calibrated to account for transformer tolerances.
2.2.1 UNDERLOAD TRACKING
The controller can optionally use under load tracking feature to characterise over time an acceptable under
load value up to a minimum setting. This characterised value becomes the reference point for the under-load
alarm. This accounts for motor current drift over time due to changing well characteristics and permits the
controller to not alarm on a set under load value but to follow the drift, and alarm based on the drift point
value.
When the under-load tracking is activated, the normal under load setting is bypassed
NOTE
for the under-load tracking setting.
Stall is a condition where the motor stops rotating. The
impedance of the power cables and motor winding create a
scenario where the power requirements are high, but this is not a
short circuit. The criteria used to define a stall condition must
consider the OVERLOAD current required during a motor start.
The set point must be set less than the name plate motor start
amps and is typically set to three times the motor rated current.
The alarm appears as STALL on the display.
This is a condition where a short circuit occurs. This indicates a
serious fault has occurred in the cable to the motor or within the
motor. The criteria used to define a short circuit must consider the
current used in a STALL condition.
The set point is typically set to six times the motor rated current.
The alarm appears as SHORT_CCT on the display.
This is the nameplate rating of the maximum continuous motor
amps.
This value is used to calculate STALL and SHORT_CCT.
Monitor condition where the power factor drops below a specified
minimum value. Used to protect a system from low power factor.
CT inputs for phase current A, B, C
Reference signal point for the three-phase current measurement.
A ground shield to protect the current signals from electrical noise.
Section 2: Theory of Operations
OPERATION
DEFINITION
10