Probewell ST-3/XT3 User manual

USER GUIDE

© Copyright 2020 by Probewell Lab Inc. Printed in Canada.
All rights reserved, including those to reproduce this manual or parts thereof, in any
form without the express written permission of Probewell Lab Inc.
ST-3/XT3
User Guide
Version 1.0 – June 2020
IT IS ESSENTIAL THAT THIS INSTRUCTION BOOK BE READ
THOROUGHLY BEFORE PUTTING THIS PRODUCT INTO SERVICE.

Probewell Lab Inc.
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Limited Warranty
Your ST-3/XT3 comes with a two-year hardware warranty. Probewell Lab
Inc., (Probewell) warrants this ST-3/XT3 against defects in material and
workmanship for a period of two (2) years from the date of purchase from
Probewell. This warranty applies only to the original purchaser of the ST-
3/XT3 and is not transferable.
All accessories come with a two-year hardware warranty. Probewell warrants
all accessories against defects in material and workmanship for a period of two
(2) years from the date of purchase from Probewell. This warranty applies only
to the original purchaser and is not transferable.
This warranty does not cover any damage caused neither by negligence, non-
authorized modifications, or parts installed without prior written permission
from Probewell.
This warranty does not apply if the product has been damaged by accident,
abuse, misuse, or misapplication, nor as a result of service to the product by
anyone other than Probewell.
PROBEWELL IS NOT RESPONSIBLE FOR ANY LOST PROFITS, LOST
SAVINGS OR OTHER INCIDENTAL OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE, OR INABILITY TO USE, OF THIS PRODUCT.
THIS INCLUDES DAMAGE TO PROPERTY AND DAMAGES FOR
PERSONAL INJURY. THIS WARRANTY IS IN LIEU OF ALL OTHER
WARRANTIES INCLUDING IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
Disclaimer
Probewell Lab Inc., (Probewell) reserves the right to make changes to this
document and the products which it describes without notice. Probewell
shall not be liable for technical or editorial errors or omissions made herein;
nor for incidental or consequential damages resulting from the furnishing,
performance, or use of this material.
Features and specifications are subject to change without notice.

ST-3/XT3 User’s Guide
Page • 3
Table of contents
Limited Warranty ....................................................................................... 2
Disclaimer .................................................................................................. 2
Table of contents ....................................................................................... 3
Introduction..................................................................................................7
ST-3/XT3 Overview .................................................................................... 7
Description ...................................................................................................9
ST-3/XT3 tester .......................................................................................... 9
Front/Rear View of the ST-3/XT3 ..................................................... 10
Side View of the ST-3/XT3................................................................ 11
Functioning Theory .................................................................................. 13
Power Quality .................................................................................. 13
CT/PT Ratio and Phase shift ............................................................. 14
CT burden ........................................................................................ 14
Admittance ...................................................................................... 15
Accessories .............................................................................................. 16
ST-3/FLEX-CT.................................................................................... 16
ST-3/PT600....................................................................................... 16
ST-3/ALW ......................................................................................... 17
ST-3/VLW ......................................................................................... 17
ST-3/EXT........................................................................................... 17
Operations..................................................................................................19
Summary.................................................................................................. 20
Installation of the ST-3/XT3 ..................................................................... 21
Connecting to the ST-3/XT3 ..................................................................... 22
Running the application........................................................................... 23
Tests available.......................................................................................... 24
Test Examples .......................................................................................... 25
Example 1: Power Quality Test: form 9S Wye with 3CT and 3PT..... 26
Example 2: CT Ratio Test: form 3S single phase with CT.................. 28
Example 3: Burden test Form 5S Delta With CT............................... 30
Example 4: Admittance : form 9S Wye ............................................ 33
Accuracy Test........................................................................................... 34
Appendix A
Specifications..............................................................................................37
Appendix B
Compatible Meter Forms Installations ........................................................ 39
Form 3S.................................................................................................... 40
Form 4S.................................................................................................... 41

Probewell Lab Inc.
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Form 5S(N) (N 2CT).................................................................................. 42
Form 5S (3∆ 2CT) ..................................................................................... 43
Form 5S (3∆ 2CT 2VT) .............................................................................. 44
Form 5S (4∆ 2CT )..................................................................................... 45
Form 5S (4Y 3CT)...................................................................................... 46
Form 5S (4Y 3CT)...................................................................................... 47
Form 5S (4Y 3CT 2VT)............................................................................... 48
Form 5S, 35S & 45S Fitzalltm (3∆ 2CT) ...................................................... 49
Form 5S, 35S & 45S Fitzalltm (3∆ 2CT 2PT) ............................................... 50
Form 5S, 35S & 45S Fitzalltm (N 2CT) ........................................................ 51
Form 5S, 35S & 45S Fitzalltm (N 2CT 2PT) ................................................. 52
Form 5S, 35S & 45S Fitzalltm (Y 3CT)......................................................... 53
Form 5S, 35S & 45S Fitzalltm (Y 3CT 2PT) .................................................. 54
Form 5S, 35S & 45S Fitzalltm (Y 2CT)......................................................... 55
Form 5S, 35S & 45S Fitzalltm (Y 3CT 2PT) .................................................. 56
Form 5S, 35S & 45S Fitzalltm (4∆ 3CT 2PT) ............................................... 57
Form 5S, 35S & 45S Fitzalltm (4∆ 3CT) ...................................................... 58
Form 6S (36S, 46S) (Y 3CT)....................................................................... 59
Form 6S (36S, 46S) (Y 3CT 2PT) ................................................................ 60
Form 6S (36S, 46S) Fitzalltm (Y 3CT) .......................................................... 61
Form 6S (36S, 46S) Fitzalltm (Y 3CT 2PT) ................................................... 62
Form 8S (4∆3CT) ...................................................................................... 63
Form 9S (4∆ 3CT) .................................................................................... 64
Form 9S (Y 3CT)........................................................................................ 65
Form 9S (Y 3CT 3PT)................................................................................. 66
Form 35S (3∆) .......................................................................................... 67
Form 45S (4∆ 2CΤ)................................................................................... 68
Form 45S (4Y 2CT 2VT)............................................................................. 69
Appendix C
Form Configurations ...................................................................................71
Appendix D
Powering the unit .......................................................................................73
Appendix E
Customer Service ........................................................................................75
Appendix F
Recommendations...................................................................................... 77

ST-3/XT3 User’s Guide
Page • 5
List of Abbreviations
Abbreviation
Complete Term
A
Ampere
Amp
Ampere
AC
Alternating Current
CFM
Cubic feet per minute
CSV
Comma separated value
CT
Current Transformer
DSP
Digital Signal Processor
I
Current
kW
Kilowatt
Lb(s)
Pound(s)
NIST
National Institute of Standard and Technology
P
True Power
PF
Power Factor
PPE
Personal Protective Equipment
PPI
Pore per inch
PQ
Power Quality
PT
Potential Transformer (same as VT)
Q
Reactive Power
RMS
Root Mean Square
S
Apparent Power
THD
Total Harmonic Distortion
U
Voltage
V
Volt
VAR
Volt-Ampere Reactive (same as Q)
VA
Volt-Ampere (same as S)
VAC
Volt AC (same as Vrms)
VDC
Volt Direct Current
VT
Voltage Tranformer

Probewell Lab Inc.
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W
Watt (same as P)
Wh
Watthour
µWh
Micro-Watthour
µVARh
Micro-VARhour

ST-3/XT3 User’s Guide
Page • 7
Chapter 1
Introduction
The Probewell Lab ST-3/XT3 is the first socket type transformer rated
site tester with built-in WiFi technology.
ST-3/XT3 Overview
The ST-3/XT3 tester weighs only 4.5 lbs, an ideal tool for testing in the
field. Within a few minutes, a CT/PT instrument-rated installation can
be accurately tested on site by field technicians. The ST-3/XT3 can
perform Power Quality test, Real time wave form analysis, Voltage and
Current phase angle, Total Harmonic Distortion analysis, CT/PT ratio
and phase shift, Burden test and Admittance test.
The ST-3/XT3 comes in a shock resistant carrying bag with room for the
unit, cable accessories and adapters.
Included in the kit:
•ST-3/XT3
•Ten removable twist tabs
oFive installed on the ST-3/XT3
oFive spares in the pocket inside the carrying bag.
•Quick-Start guide
•User’s guide
•Factory calibration report
•Adapter for 5S, 35S and 45S installations
•Update cable

Probewell Lab Inc.
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ST-3/XT3 User’s Guide
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Chapter 2
Description
The first part of this chapter shows a detailed description of the
ST-3/XT3. The second part explains its functioning theory.
ST-3/XT3 tester
The ST-3/XT3 is cylinder-shaped, designed to be easily inserted in both
ringless and ring-type meter bases.
The ST-3/XT3 contains three current sensors up to 20 Amps to analyze
the secondary current from the meter base.
The ST-3/XT3’s rear has 6 standard fixed tabs with bypasses that can be
open for the burden testing and 6 removable twist tabs, with twist &
lock mechanism. The ST-3/XT3 obtains its power directly from these
back tabs and accepts an input voltage from 100 to 480 VAC (voltage
above 480+10% will not damage the unit, but it will not start).
The twist tabs are located at positions 5a, 11, 12, 13, 16 and 17 as
required by the meter base where the test is conducted. The twist tab
at 12 can be position at 2 different positions to hold either forms
6S/8S/9S or form 3S/4S. The twist tab at position 16 can be positioned
at 2 different positions to hold either forms 6S/8S/9S or forms 4S. The
twist tab at position 5a can be used for some 3S installation where the
jaw is at the 6 o’clock in the meter bases. See Appendix C for all back-
twist tab configurations.
The ST-3/XT3’s front has two 12 pins connectors for the primary
measurements accessories.

Probewell Lab Inc.
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Front/Rear View of the ST-3/XT3
Fig. 2.1
Fig. 2.1 shows the removable twist tabs, they can be moved without the
use of tools. The above illustration shows only the twist tab positioned
at 11-13 and 16-17.
Nominative Plate that includes
the serial number and WiFi
Access Point QR Code
Nominative Plate that includes
the serial number and WiFi
Access Point QR Code
5x small removable
Twist tabs

ST-3/XT3 User’s Guide
Page • 11
Side View of the ST-3/XT3
Fig. 2.2
Fig. 2.2 LED Status: Solid green means the device is ready, blinking green
means there is an active test and blinking red if there is a system error.

Probewell Lab Inc.
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Identification
Brief Description
Current Tabs
Connect the ST-3/XT3 tester to the front jaws of
the meter base.
Removable Twist
Tabs
These tabs can be easily installed at position 5a, 11,
12, 13, 16 and 17 as required by the meter base
where the test is conducted. See Appendix C.
Form Selector
In position 3S/4S, the unit is powered from the tab
at position 12 and the current tab at position 2. In
position 6S/8S/9S, the unit is powered from the tab
at position 11 and the current tab at position 2.
Note: if the 5S adapter is used, the form selector
must be set to 6S/8S/9S position
Circuit Breakers
Protection for the ST-3/XT3. Two 1A circuit
breakers which can easily be reset by pressing a
spring-loaded button.
Power Switch
ST-3/XT3 main power on/off switch.
Connectors
There are two 12 pins connector located on the
front of the ST-3/XT3 for accessories. The one
identified as CT is to connect
primary current
measurements accessory
. The second connector
identified as PT is to connect the primary voltage
measurements accessory when PT is used.
RS 232 I/O Port
This connector is used only for updating the
firmware of the ST-3/XT3.
Air Vent
(1)
Warm air exit. A 5 CFM miniature fan forces air
circulation inside the unit.
Air Inlet
(1)
Cool air input. Filtered through 45PPI polyurethane
foam filter.
(1)
Do not block air circulation. Keep away from direct heat or flame.

ST-3/XT3 User’s Guide
Page • 13
Functioning Theory
The ST-3/XT3 accurately measures and analyzes CT/PT meter
installations. You can easily test the Power Quality (PQ), real time
waveform analysis, phasors, Total Harmonic Distortion (THD), CT/PT
ratio, CT Burden and Admittance.
Embedded within its core, is a high-performance multiphase energy
metering circuitry enabling a full RMS and line cycle measurement of
both secondary and primary currents and voltages.
With the ST-3/XT3 installed and the bypass removed (in the meter
base), the CT is never open as the ST-3/XT3 always keeps the closed
loop on the secondary.
The ST-3/XT3 can display instantaneous RMS reading for voltage and
current. The hardware within can get an averaged RMS over 12 cycles
at 60 Hz and we could also run a moving average over a bigger set of
RMS readings to reduce the effect of load fluctuations.
Power Quality
The power quality function gives you all the information collected by
the ST-3/XT3 at the meter base, such as voltages on each phase (U),
current for each phase (I), real power in Watt (P), reactive power in VAR
(Q), apparent power in VA (S), phase angle for the voltage and current
of each phase, power factor, THD in both voltage and current and the
frequency.
This test can be conducted with or without primary measurement
accessories.
Phasors
This vectorially graphical function give you the angles between each
phase in current and voltage in relation to the voltage of Phase A.

Probewell Lab Inc.
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Waveform analysis
This graphical function that gives you a time-based sinewave
representation of the voltage and current on the meter base. You can
also isolate each phase to see the relation between the voltage and
current. The view displays 2 cycles of the current and voltage.
Total Harmonic Distortion (THD)
This bar graphical display gives you the relation between the
fundamental frequency and all the harmonics up to the 22nd harmonics.
CT/PT Ratio and Phase shift
You must have accessory to conduct this test.
This test is to ensure that the ratio between the input current and the
output current are the same as indicated on the transformers being
tested. It is performed with the accessories provided with the ST-3/XT3.
Example: if the name plate is 400:5 the nominal input current is 400 A
and the output at the secondary is 5 A. For example, if the ST-3/XT3
reads a primary input current of 399 and an output at the secondary of
4.98A, this gives a ratio of 400:5.
The test can also give the phase relationship between the primary and
secondary.
CT burden
Current transformer burdens are typically expressed in VA. The burden
test is performed to verify that the CT can supply a known current into
a known burden while maintaining its stated accuracy. A burden test is
typically performed at full rated secondary current value (ex. 5A or 1A).
By applying a precision resistance in series with the CT secondary, the
ST-3/XT3 verifies that the current sample and analyze the deviation in
accordance with the value without resistance.

ST-3/XT3 User’s Guide
Page • 15
All the phases (A, B, C) are done sequentially until it reaches the Max
burden value selected in the application software - Probewell Connect.
This test can be done with or without CT accessory, but best result will
be reach with CT accessory since the primary/secondary will be tracked
in real-time. Without CT accessory, the test takes a snapshot of the
secondary current as its baseline.
Admittance
By injecting a small audio of 1500 kHz into the CT secondary, then
measuring the induced current of the audio frequency to determine the
admittance value.
Analog filtering and programmable gain are used to get the best
dynamic range for the DSP to compute the admittance @ 60Hz. While
CT burden needs secondary current to achieve its purpose, the
admittance needs small or no current (max 0.5A) on the secondary side.
If the current is higher than 0.5A, the test will not be conducted.
All the phases are done sequentially.
This test can be done with or without accessory.

Probewell Lab Inc.
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Accessories
The ST-3/XT3 comes with several optional accessories for primary
measurements.
ST-3/FLEX-CT
The ST-3/FLEX-CT current probes are Rogowski coils, they are an electrical
device for measuring the primary current of a CT. It consists of a helical coil of
wire with the lead from one end returning through the center of the coil to the
other end, so that both connections are at the same end of the coil. The probe
can be easily placed around the wire going through the CT and be secure with
a latch.
The ST-3/FLEX-CT is used for comparing primary to secondary current, with
auto-detection and electronically compensated with an accuracy of 0.5% and a
current range up to 2500A for the ST-3/FLEX-CT2500 and up to 5000A for the
ST-3/FLEX-CT5000. The window size is 10.67'' (271mm), the cable is 15 feet
long.
ST-3/PT600
The ST-3/PT600 is electrical devices that converts high voltage reading and
send it as a lower voltage to be read by the tester. The probes can be easily
installed with crocodile clamps to the terminal of the primary voltage of the
potential transformer (PT).
The three phases primary line voltage clamps, no neutral 1, comes with auto-
detection and is electronically compensated with an accuracy 0.1% and a
voltage range up to 600V. Three color-coded 4mm banana jack, dolphin
clamps are included. The cable is 15 feet long.
1The neutral is taken from the ST-3/XT3

ST-3/XT3 User’s Guide
Page • 17
ST-3/ALW
The ST-3/ALW is the interface to a SensorLink®’s AMP LiteWire.
ST-3/VLW
The ST-3/VLW is the interface to a SensorLink®’s VOLT LiteWire.
ST-3/EXT
The extension cable is used when the primary CT or PT is far from the meter
installation. They are compatible with ST-3/FLEX2500, ST-3/FLEX5000 and ST-
3/PT600 accessory.
•ST-3/EXT50 is 50 feet.
•ST-3/EXT100 is 100 feet.
When using one of these extensions on primary current or primary voltage
accessory previously described, the performance of the accessory will be
derated, see Specifications section.

Probewell Lab Inc.
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ST-3/XT3 User’s Guide
Page • 19
Chapter 3
Operations
CAUTION
The use of ST-3/XT3 is strictly reserved to personnel authorized to
manipulate CT rated meter installations. For safety reasons, certified
PPE such as safety glasses and rubber gloves are strongly
recommended but are not provided with the ST-3/XT3.
The operation of removing and inserting a meter from its meter base
under power exposes live electric terminals. Be careful. Do no stick
your hands or any metal objects into the open meter base. You could
suffer bodily burns, electric shocks and even electrocution.
It is imperative you follow your company safety procedures.
Do not open the CT secondary loop!
Opening the CT secondary may cause damage to the
current transformer and/or operating personnel.