TECSYSTEM NT935 WS User manual

1MN0201 REV. 0
operates with ISO9001 certified quality system
http://www.tecsystem.it
R. 1.1 16/11/20
“Translations of the original instructions”
INSTRUCTION MANUAL
NT935 WS EVO
TECSYSTEM S.r.l.
20094 Corsico (MI)
Tel.: [phone]
Fax: [phone]
ENGLISH

2
NT935 WS EVO
PAGE
1) SAFETY REQUIREMENTS
………..........................................
4
2) ACCESSORIES
…………………………………..
5
3) TECHNICAL SPECIFICATIONS
…………………………………..
6
4) FRONT PANEL
…………………………………..
8
•DISPLAY
…………………………………..
9
•OPERATING PROGRAM CONTROL
………………………………….
—
•NOTES ON SCAN AND MAN FUNCTIONS
…………………………………..
—
•LED TEST
…………………………………..
—
•ALARM RELAY TEST
…………………………………..
—
•ALARM RELAY SILENCING
…………………………………..
—
5) ASSEMBLY
…………………………………..
10
6) ELECTRICAL CONNECTIONS
…………………………………..
11
•REAR NT935 WS EVO
…………………………………..
—
•POWER SUPPLY
…………………………………..
12
•ALARMS AND VENTILATION
…………………………………..
—
•FAULT AND RESET MESSAGE SEQUENCE
…………………………………..
—
7) PROGRAMMING
…………………………………..
13
•NT935 WS EVO
…………………………………..
—
•PROGRAMMING NOTES
…………………………………..
14
•TEMPERATURE SENSORS
…………………………………..
15
•MEASUREMENT SIGNAL TRANSFER
…………………………………..
—
•TEMPERATURE SENSOR DIAGNOSTICS
…………………………………..
16
•VOTING FUNCTION
…………………………………..
—
•PROGRAMMED DATA DIAGNOSTICS
…………………………………..
—
•TEMPERATURE DIAGNOSTICS
…………………………………..
—
•COOLING FAN CONTROL
…………………………………..
17
•FAN TEST
…………………………………..
—
•INTELLIFAN FUNCTION
………………………………….
—
INTRODUCTION
INDEX
First of all we wish to thank you for choosing to use a TECSYSTEM product and recommend you read this instruction
manual carefully: You will understand the use of the equipment and therefore be able to take advantage of all its functions.
ATTENTION! THIS MANUAL IS VALID AND COMPLETE FOR THE NT935 WS EVO MODEL CONTROL UNIT.

3
NT935 WS EVO
PAGE
8) FAILSAFE FUNCTION
…………………………………..
18
9) Pt100 EXTENSION CABLE TECHNICAL
SPECIFICATIONS
…………………………………..
—
10) FCD FUNCTION
…………………………………..
19
11) NT935 WS EVO WI-FI CONNECTION
…………………………………..
—
12) TECSYSTEM WEB SERVER
…………………………………..
21
•HOME SCREEN
…………………………………..
22
•TEMPERATURE AND ALARMS SCREEN
…………………………………..
—
•SETTINGS SCREEN
…………………………………..
23
•NETWORK SETTINGS
…………………………………..
24
•OPTIONS
…………………………………..
25
•E-MAIL SETTINGS
…………………………………..
26
•TREND CHART SCREEN
…………………………………..
27
•EVENT LOG SCREEN
…………………………………..
28
•TREND CHART NOTES
…………………………………..
29
•CSV FILE EXPORT NOTES
…………………………………..
—
•PIN CODE
…………………………………..
—
•STATISTICS SCREEN
…………………………………..
30
•PERIODIC REPORT
…………………………………..
—
13) TROUBLESHOOTING
…………………………………..
31
14) WARRANTY REGULATIONS
…………………………………..
—
15) EQUIPMENT DISPOSAL
…………………………………..
32
16) USEFUL CONTACTS
…………………………………..
—

4
NT935 WS EVO
SAFETY REQUIREMENTS
ATTENTION:
Read the manual carefully before starting to use the control unit. Keep the instructions for future reference.
Do not open the device. Touching any internal components can cause electric shock. Contact with a voltage over 50
Volts can be fatal. To reduce the risk of electric shock, do not dismantle the back of the device for any reason. Moreover
its opening would void the warranty.
Before connecting the device to the power supply, make sure that all the connections are correct. Always
disconnect the unit from the supply before any cabling modification.
Any work on the equipment must be entrusted to a qualified engineer.
Failure to comply with these instructions can cause damage, fires or electric shock, and possible serious
injuries!
POWER SUPPLY
The NT935 WS EVO can be supplied by 85 to 260 Vac-Vdc, irrespectively of polarity in Vdc.
Before using it, make sure the power cable is not damaged, knotted or pinched. Do not tamper with the power cable.
Never disconnect the unit by pulling the cable and avoid touching the pins. Do not carry out any operations of
connecting/disconnecting with wet hands. To disconnect the device, do not use objects such as levers. Immediately
disconnect the device if you smell burning or see any smoke: contact assistance.
LIQUIDS
Do not expose the equipment to splashes or drops, do not position it in places with humidity exceeding 90% and never
touch with wet or damp hands. If any liquid penetrates the control unit, disconnect it immediately and contact technical
assistance.
CLEANING
Disconnect the power cable before cleaning the control unit, use a dry cloth to dust it, without any solvent or detergents,
and compressed air.
OBJECTS
Never insert any objects into the cracks of the control unit. If this happens, disconnect the control unit and contact an
engineer.
USE RESERVED TO QUALIFIED PERSONNEL
The purchased goods are a sophisticated electronic device that is completely unsuitable to be used by non-qualified
personnel. Any work must be carried out by a specialist engineer.
ACCESSORIES
The use of non-original accessories or spare parts can damage the unit and endanger users' safety. In the event of
faults, contact technical service.
LOCATION
Install the control unit indoors, in a place protected from water splashes and from the sun’s rays. Do not place near heat
sources exceeding the parameters stated in this manual. Position on a stable surface, far away from any possible
vibrations. Position the unit as far as possible from any intense magnetic fields.
REPAIRS
Do not open the control unit. For any fault, always use qualified personnel. The opening of the control unit and/or the
removal of the series identifying label entails the automatic forfeiture of the warranty. The Warranty seal is applied to all
devices, any attempt to open the unit would break the seal and cause the consequent automatic forfeiture of the
warranty.
BATTERY
Inside the NT935 WS EVO device there is a lithium manganese dioxide battery. Do not open the control unit; the battery
used is maintenance-free. Do not expose the device to temperatures above or below the operating range (–20°C to
+60°), do not expose it to fire (risk of explosion). In case of liquid leakage from the product and possible contact with
persons (hands, eyes or other) or inhalation, contact your doctor immediately.
FUNCTIONS
To control the transformer correctly from a temperature point of view, enabling of the VOTING function is
permitted where the load distributed between the phases of the transformer is adequately balanced.
TECHNICAL INFORMATION OR REPORTING INFORMATION
Mail: [e-mail] –tel.: [phone]

5
NT935 WS EVO
The following objects are present inside the box:
Control unit
Start guide and QR code
2 blocks for panel fixing
1 Terminal 3 pitch poles 5 supply
Code: 2PL0367 - Screw tightening torque 0.5Nm
1 terminal 12 pitch poles 5 relays
Code: 2PL0361 - Screw tightening torque 0.5Nm
1 Terminal 12 poles pitch 3.81 sensors Pt100
Code: 2PL0420 - Screw tightening torque 0.25Nm
1 external Wi-Fi SMA Antenna
ACCESSORIES
ATTENTION: always install the device using the terminals included in the pack.
The use of terminals other than those included with the control unit could cause malfunctions.

6
NT935 WS EVO
TECHNICAL SPECIFICATIONS
NT935 WS EVO
POWER SUPPLY
Supply rated values
85-260 Vac-Vdc
50/60HZ
Vdc with invertible polarities
●
INPUTS
4 inputs for three-wire Pt100 RTD sensors (max section 1.5mm²)
●
Connections on removable terminal boards
●
Input channels protected against electromagnetic interference
●
Thermoresistances cable compensations
500m (1mm²)
OUTPUTS
2 alarm relays (ALARM AND TRIP) SPDT
●
1 sensor or operating failure (FAULT) relay SPST
●
2 ventilation management relays (FAN 1 and FAN 2) SPST
●
Output relays with 10A-250Vca-res COSФ=1 contacts
●
Wi-Fi Connection: protocol 802.11 b/g/n, frequency 2.4 GHz with removable external antenna
Max 100m
in open field
DIMENSIONS
100 x 100 mm DIN 43700 prof. 150 mm (including antenna - installed at 90°C - and terminal
board)
Hole 92 x 92 mm
TESTS AND PERFORMANCE
Construction in compliance with the EC - RED regulations
●
Protection from electrical interferences EN 61000-4-4
●
Dielectric strength 1500 Vac for a min. between output relays and sensors, relays and power
supply, power supply and sensors
●
Accuracy ±1% full scale value, ±1 digit
●
Ambient operating temperature from –20°C to +60°C
●
Permitted humidity 90% without condensate
●
Polycarbonate frontal film IP65
●
Housing NORYL 94 _V0
●
Absorption 7.5VA
●

7
NT935 WS EVO
TECHNICAL SPECIFICATIONS
NT935 WS EVO
Digital linearity of sensor signal
●
Self-diagnostic circuit
●
Electronic part protective treatment
Optional
Internal battery for RTC power supply
3V 220mAh
DISPLAY AND DATA MANAGEMENT
2 x 13 mm displays with 3 digits to display temperatures, messages and channels
●
3 LEDs to display the state of the alarms of the selected channel (ALARM-TRIP-FAULT)
●
4 LEDS selection of display mode (SCAN-AUTO-MAN-T-MAX)
●
2 LEDs to display the state of FAN1 and FAN2
●
Temperature control from 0°C to 240°C (*)
●
2 alarm thresholds for channels 1-2-3
●
2 alarm channels for channel 4
●
2 ON-OFF thresholds FAN 1 and FAN 2 ventilation
●
Sensor diagnostics (Fcc-Foc-Fcd)
●
Data memory diagnostics (Ech)
●
Access to programming through front keyboard
●
Automatic exit from programming, display and relay test after 1 minute of inactivity
●
Incorrect programming warning
●
Selection between channels automatic scanning, hottest channel or manual scanning
●
Storage of maximum temperatures reached by channels and alarm status
●
Front key to reset the alarms
●
Voting Function
●
Intellifan function
●
Fail Safe Function
●
WEB SERVER Wi-Fi Function
●
Internal clock keeping in STATION (NTP server) and ACCESS POINT mode
●
Automatic sending of alarm activation e-mails
●
Periodic sending of channel statistics reports
●
(*) On request, reading version -40°C to 200°C with alarm temperature control from 0°C to 200°C

8
NT935 WS EVO
1)
3-digit temperature display
12)
Enter/Reset button
2)
Control unit series
13)
Programming/Setting key
3)
TRIP (red) LED
14)
Led/relay test key
4)
ALARM signalling (yellow) LED
15)
WI- FI (green) LED
5)
FAULT (red) LED
16)
3-digit channel display
6)
FAN 1 (yellow) LED
17)
T-max mode selection (red) LED
7)
FAN 2 (yellow) LED
18)
Man mode selection (yellow) LED
8)
Display mode selection key
19)
Auto mode selection (green) LED
9)
Fixing blocks
20)
Scan mode selection (yellow) LED
10)
UP key
21)
Fixing blocks
11)
DOWN key
1
2
3
4
5
6
7
8
9
10
11
12
14
13
15
16
17
18
19
20
1MN0201 REV.0
21
FRONT PANEL

9
NT935 WS EVO
DISPLAY
The first display is dedicated to temperatures.
The second display to the monitored channel.
When the device is switched on or after a reset, the NT935 control unit model, the type of probes, the temperature range, the
VER "00" indication (firmware version) and the device identification code WS EVO (web server) option appear on the display.
Pressing the MODE key, the display modes can be set:
•SCAN: the control unit shows in scanning (every 2 seconds) all the enabled (°C) and disabled (NO) channels.
•AUTO: the control unit displays the hottest channel automatically.
•MAN: manual reading of the channel temperature using the up/down keys
•T.MAX: The display shows the maximum temperature of the channel selected with the cursor keys. In the event of a fault,
the Tmax value is replaced with the type of fault stored (fcc-foc). Turning on the Trip-Alarm-Fault LED warns of any events
that have occurred. The recordings are always successive to the moment in which the T.Max is reset (by pressing RESET).
OPERATING PROGRAM CONTROL
To control the protection levels programmed, press the PRG key twice to access the VIS programme. Repeatedly pressing
the PRG key, you can scroll through all the previously loaded values in sequence.
After 1 minute's keyboard inactivity, the programming display procedure is automatically abandoned.
To stop the display, press the ENT key.
NOTES ON SCAN AND MAN FUNCTIONS
During the SCAN and MAN modes, the operation of the NT935 can be displayed.
1) RUN cPU:
This message appears upon ignition of the device.
2) Ech Err:
This message appears when damage in the EEPROM memory is detected.
Pressing Reset will cancel the message and restore the originaldefault parameters, listed in the programming paragraph
on pages 13-14. Return the control unit to TECSYSTEM for repairs.
3) CAL Err:
This message appears when damage is found in the measurement circuit.
The temperature values displayed might be incorrect. Return the control unit to TECSYSTEM for repairs.
4) Pt Err:
This message appears when it is detectedthat one or more PT100 sensors are not working correctly, FOC, FCC and
FCD indications in the temperature sensor diagnostics paragraph on page 16.
In case of Err the FAULT relay will be de-energised.
The above messages will be displayed following the 1-2-3-4 priority stated.
In any display mode in case of faulty sensor failure (fcc, foc or fcd) the control unit will automatically set up in SCAN mode
(PRIVILEGED SCAN) allowing immediately displaying of the fault condition on the relative CHn channel (the Mode key is
disabled).
LED TEST
We suggest carrying out the control unit LED test regularly.
For this operation, press the TEST key briefly; all the displays turn on for 2 seconds.
If one of the LEDS does not work, please return the control unit to TECSYSTEM for repair.
ALARM RELAY TEST
This function allows you to carry out a test of the relay operation without having to use further devices. To start the test
procedure, press and hold the TEST button for approximately 5 seconds: the TST indication appears for 2 seconds confirming
entry into the Relays Test mode.
L The LED that is lit shows the relay to be tested; use the cursors to select the desired relay.
Press the SET and RESET keys to energise and de-energise the relay to be tested; the display will show ON-OFF.
After 1 minute's keyboard inactivity, the RELAY TEST procedure will be automatically abandoned.
To stop the RELAY TEST procedure, press the TEST key.
Alternatively it is possible to use the PT100 model simulator: SIM PT100.
ATTENTION: accessing at the relay test mode will temporarily disable the failsafe function, the relays with function
enabled switch (ALARM-TRIP-FAULT).
ALARM RELAY SILENCING
To silence the ALARM signal, press the RESET key: the relay will de-energise and the ALARM LED, which is on steady, will
start to flash. Silencing is automatically disabled when the temperature goes below the ALARM threshold.

10
NT935 WS EVO
Secure the appliance firmly by means of the supplied fixing blocks.
Connect the Wi-Fi antenna only after suitably fixing the device.
1)
Control unit
2)
Panel hole dimensions (+0.8 mm tolerance)
3)
Identification label
1)
Control unit
3)
Fixing screws
2)
Fixing blocks
4)
Cross-head screwdriver #1X100mm
ASSEMBLY
Drill a hole in the panel sheet with dimensions of 92 x 92 mm.
1
1MN0007 REV. 0
2
3
1
2
3
4
1MN0008 REV. 0

11
NT935 WS EVO
NT935 WS EVO
SCREEN RED RED WHITE
4
Note: image relay contacts in non-alarm condition, except for the FAULT relay which switches: contacts 11-12 open
(NO) contacts 11-12 closed (NC) fault condition identification. Read paragraph Alarms and Ventilation page 12 and
see image of fault contact opening.
RELAYS CONNECTION EXAMPLE
1
2
3
5
1)
Pt100 sensors (white-red-red)
4)
Access point key
2)
Power supply 85-260Vac-cc 50/60Hz.
5)
Antenna and Wi-Fi connector
3)
Relays (FAN2-FAN1-ALARM-TRIP-FAULT)
1MN0095 REV. 0
Output relay with contacts of 10A-250Vac-res COSФ=1.
COSФ=1.
STOP
SYSTEM
INDICATION
AUDIBLE AND VISUAL
ALARM CONDITION
Pt100 CONNECTION EXAMPLE
Note: before connecting the probes
to the control unit, carefully read the
paragraph measurement signal
transfer on page 15.
1MN0201 REV.0
ELECTRICAL CONNECTIONS
The Wi-Fi antenna (5) is supplied with the NT935 WS EVO
device. If necessary, the antenna connection can be extended
using a 5 mm SMA Male to Female antenna cable.
NOTE: Never start the device with the antenna
disconnected.

12
NT935 WS EVO
POWER SUPPLY
The NT935 WS EVO can be supplied by 85 to 260 Vac-Vdc, 50/60Hz irrespectively of the polarity in Vdc (terminals 40-42).
This particularity is obtained thanks to the use of a tested power supply, of new conception and realisation,
which frees the installer from any uncertainty regarding the correct Vac or Vdc power supply.
The earthing cable must always be connected to terminal 41.
When the control unit is powered directly by the secondary of the transformer to be protected, it can be burnt out by high
intensity overvoltages.
These problems occur if the main switch is closed and the transformer does not have the load (no load test).
The above is much more evident when the 220 Vac voltage is taken directly from the bars of the secondary of the transformer
and there is a fixed capacitor battery for power factor correction of the transformer itself.
If an existing control unit must be replaced with a new one, to guarantee its correct and safe operation, the
sensor/relay/supply connecting terminals must be replaced with the new terminals supplied.
ALARMS AND VENTILATION
Carry out the electrical connections on the removable terminal blocks only after disconnecting them from the unit.
When the control unit is in one of the following modes, it does not perform any thermal monitoring, moreover the relays will
all be disabled, the fault contact switches and the fault LED will flash.
•Vis. Programming display.
•PRG programming.
•Relay test.
The ALARM and TRIP relays only switch when the set temperature thresholds are exceeded.
The FAULT (fault)contact, programmed in active failsafemode (default YES), opens (11-12) when the appliance is powered,
only if during the access phase the control unit does not detect anomalies, and keeps the switching until when one of the
following events occurs:
•Data memory fault (Ech message).
•Pt100 sensor fault (FCC short-circuited sensor, FOC interrupted sensor or Fcd quick temperature increase)
•CAL damage to the measurement circuit.
•Insufficient supply voltage.
•During the power on reset after programming (PRG), displaying the data (VIS) and relay test.
The FAULT failsafe mode can be disabled FAULT failsafe "NO" see programming step 34-35 page 14.
NOTE: in order to avoid unwanted system outages, do not connect the FAULT relay to the transformer tripping circuit.
FAULT AND RESET MESSAGE SEQUENCE
Find below the sequence of fault messages and RESET function condition.
1) ECH
2) CAL
3) FCD
4) ERR PT
The FAN1 and FAN2 contacts can be used to control the cooling fans, or they can be inserted in the conditioning system of the
transformer room, see paragraph cooling fan control on page 17.
NOTE: always disconnect the unit before performing any electrical connections.
11 12
FAULT 11-12 NC: ALARM FAULT OR POWER OFF
FAULT 11-12 NO: POWER ON OR NO FAULT
11 12
FAULT CONTACT (failsafe active)
eeprom fault
measurement circuit fault
Temp. increase rapid fault
FCC or FOC sensor fault
erasable message
erasable message
resettable condition
non-resettable condition
To protect the control unit against line overvoltages, the PT-73-220 electronic arrester, designed by TECSYSTEM S.r.l.
for this specific purpose, is recommended. Alternatively, it is advisable to use 110 V AC supply voltages or, even better,
110 VDC.

13
NT935 WS EVO
PITCH
PRESS
EFFECT
PRESS
NOTES
1
Press and hold the PRG button until the
display shows SET PRG
2
Select PRG SET to proceed with programming or PRG 1
to load the default values
PRG 1 default data
3
The ALARM threshold for (CH 1-2-3) is displayed.
Set the desired threshold, the Alarm LED flashes
Default 90°C
4
The TRIP threshold for (CH 1-2-3) appears and the Trip
LED flashes.
5
Set the desired threshold
Default 119°C
6
The display shows FAN 1 (CH 1-2-3)
LED Fan1 flashes.
Default YES
7
Select YES/NO/INT
If INT is selected
read function notes page 17 .
8
The display shows (CH4)
Enabling CH4
9
Select YES or NO
with YES the CH4 is enabled
with NO the CH4 is disabled
10
The ALARM threshold for (CH4) appears and the Alarm
LED flashes.
If CH4=NO jump to step 16,
Default NO
11
Set the desired threshold
Default 120°C
12
The TRIP threshold for (CH4) is displayed.
The TRIP LED flashes
13
Set the desired threshold
Default 140°C
14
The display shows FAN 2 for CH4
Default Yes
15
Select YES/NO
16
The display shows ON (CH 1-2-3),
the FAN1 LED flashes
Default 70°C
17
Set the desired threshold FAN1 ON
Selecting FAN 1 NO skip to
step 21 selecting INT the
LEDs of FAN1 and FAN2
flash
18
The display shows OFF (CH 1-2-3),
the FAN1 LED flashes
Default 60°C
19
Set the desired threshold FAN1 OFF
PROGRAMMING
NT935 WS EVO

14
NT935 WS EVO
20
The display shows ON (CH4),
the FAN 2 LED flashes
Default 45°C
21
Set the desired threshold FAN2 ON
If FAN 2 NO is selected skip to
step 24
22
The display shows OFF (CH4)
the FAN2 LED flashes
Default 35°C
23
Set the desired threshold FAN2 OFF
24
HFN (NO) is displayed
The FAN1-FAN2 LEDs flash
Fan cyclic test
for 5 min. every “n” hours
25
Set the desired number of hours
Default NO = function
disabled
26
FCD (NO) is displayed
Fault for quick temperature
increase (°C/sec)
27
Set the desired value
(FCD info on page 19)
Default NO
(function excluded)
28
VOT (NO) is displayed
(VOTING info on page 16)
29
Select YES or NO
Default NO
(function excluded)
30
FLS (ALARM) is displayed
Blinking ALARM LED
(info FAIL SAFE on page 18)
31
Select YES or NO
Default NO
32
FLS (TRIP) is displayed
Blinking TRIP LED
33
Select YES or NO
Default NO
34
FLS (FAULT) is displayed
Blinking FAULT LED
35
Select YES or NO
Default YES
36
END is displayed
End of programming
37
Press ENT to save the set data
and exit programming
incorrect programming of the
LED values indicated (note 6)
38
Return to step 1
PROGRAMMING NOTES
1) The MODE key allows reversing the programming steps according to the sequence 28-26-8-1
2) The TEST key allows exiting programming without saving the modified data.
3) After 1 minute's keyboard inactivity programming is abandoned without saving the data.
4) During programming the control unit does not control/protect the monitored machine.
5) At the end of programming the control unit is restarted and the FAULT relay is disabled until the unit is fully restarted.
6) If pressing ENT, “Err” appears, it means that one of the following mistakes has been made:
ERR ALL. = ALARM ≥ TRIP
ERR FAN = FAN-OFF ≥ FAN-ON. (FAN1 OR FAN2)
ERR INT = INT FAN-OFF ≥ FAN-ON (FAN1) DELTA <10°C
The device automatically prepares itself for the programming step of the error committed
NOTE: EVERY TIME THE CONTROL UNIT PROGRAMMING, WITH CONFIRMATION OF DATA SAVING, THE
VALUES STORED IN T-MAX ARE RESET AT THE TIME OF STORING.

15
NT935 WS EVO
All "NT" series control units have linearity of the sensor signal, with a maximum error of 1% of full scale value.
NOTE: the use of cables not complying with the above could cause possible reading anomalies. It is always
important to take into account that any interference on the signal lines might cause anomalies on the Pt100
inputs (CH1-CH2-CH3-CH4.) or on the sensors themselves.
ATTENTION:
We recommend you check the device's programming before starting the device.
The default parameters set by TECSYSTEM might not match your requirements.
Programming the device is the end user's responsibility. The settings of the alarm thresholds and enabling of the
functions described in this manual must be checked (by a specialist engineer) according to the application and
features of the system the control unit is installed on.
TEMPERATURE SENSORS
Each Pt100 thermometric sensor has a white conductor and two red ones (CEI 75.8 standards).
The CH2 channel must always refer to the central column of the transformer.
The CH4 channel must refer either tothe transformer core, orto the Pt100 roomsensor whenever it is necessary tothermostat
the transformer room using the NT935 WS EVO control unit.
MEASUREMENT SIGNAL TRANSFER
All the Pt100 measurement signal transfer cables must strictly comply with the following rules:
1. Every Pt100 must be connected with a three-wire cable with a minimum section of 0.35mm² and a maximum of 1 mm².
2. The extension cable must be screened with tinned copper braid with an 80% cover
3. Conductors must be twisted, maximum recommended step 60mm
4. The cable screening must only be earthed with a termination, preferably on the control unit side.
5. The sensors' signal transfer cable must not be near electrical cables, either low or medium-high voltage.
6. The Pt100 cable and the signal transfer cable must be laid in a straight line, without any winding.
7. Any caps used to butt conductors must be crimped properly to avoid false contacts.
NOTE: to install the sensors and signal transferring cable correctly, read the SCS/PT100 SENSORS installation note
manual.
What may happen when installation rules are not complied with.
1)The electrical field propagating from the power line of another circuit couples capacitively with the conductors (in particular
with unscreened cables). The effect of this coupling creates a signal that overlaps the signal transmitted by the nearby
conductors, causing incorrect readings.
2) The variations in magnetic flux in the power lines may induce an electromotive force on the signal transferring cables (in
particular non-twisted cables), that, being a closed circuit, generates a current. This interference current, multiplied by the
circuit resistance, gives a voltage value that overlaps the signal to be transmitted, distorting the sensor measurement.
3) False contacts can alter the signal with the consequent variation in the temperature detected.
In specific cases, when the rules for connecting the Pt100 sensors are not complied with, the following anomalies can occur
between the SCS box and the temperature control unit:
a) incorrect temperature readings, alarms or anomalous tripping
b) mechanical/electrical fault of the Pt100 sensors
c) damage to the Pt100 inputs of the control unit.
TECSYSTEM S.r.l. has designed its own special cable to transfer the measurement signals, CEI-compliant, with all the
protection requirements provided for mod. CT-ES

16
NT935 WS EVO
TEMPERATURE SENSOR DIAGNOSTICS
In case of failure or exceeded full scale value of one of the thermometric sensors installed on the machine to be protected,
the FAULT relay opens immediately with the relative warning of faulty sensor on the corresponding channel.
Fcc indicates sensor in short circuit or exceeding the minimum full scale value of the control unit -8°C (for version 0° ÷
240°C) and -48°C (for version -40°C ÷ 200°C)
Foc indicates sensor interrupted or exceeding the maximum full scale value of the control unit 243°C (for version
0°÷240°C) and 203°C (for version -40°C÷200°C)
To eliminate the message and to restore the Fault contact opening, check the connections of the Pt100 and replace the
faulty sensor if necessary. In case the minimum/maximum full scale value has been reached, make sure that the
environmental conditions correspond to what is indicated by the control unit.
Note: exceeding the minimum/maximum full scale can also be caused by possible disturbances on the sensor lines, in this
case the following are recommended:
Check correct installation of the sensors and especially of the extension cable (as indicated in the paragraph
MEASUREMENT SIGNALS TRANSFER).
Activation of the functions: VOTING (shown below) or FCD (on page 19) in relation to the system conditions.
CAL message display: the indication appears when the measurement circuit is damaged. The temperature values displayed
might be incorrect. Return the control unit to TECSYSTEM for repairs.
VOTING FUNCTION
The votingfunction derives from theredundancy conceptthatconsists induplicating thecomponents ofa system to increase
their reliability.
How does VOTING work?
Using the redundancy principle, we use the sensors installed on the three phases U-V-W to monitor the transformer's
operation, and at the same time to ascertain the sensors are working correctly, discriminating against any false alarms
(generated by installation errors).
By activating the VOTING "YES" function, the control unit compares the temperature values recorded on the monitored
CH1-CH2-CH3 channels and enables the switching of the (TRIP) disconnect contact only if the TRIP threshold has been
exceeded on at least two channels over the same period T.
By selecting VOTING “NO” the function will be disabled.
Note: if Voting "Yes” is programmed, the switching of the ALARM contact will signal exceeding of the alarm threshold on
each individual channel.
To enable the Voting function, read the programming section on pages 13-14.
Attention: To control the transformer correctly from a temperature point of view, enabling the VOTING function
is allowed where the load distributed between the phases of the transformer is adequately balanced. In addition,
any conditions of FAULT: FCC-FOC-FCD on two or more channels, with active voting, can determine the TRIP
contact inhibition.
PROGRAMMED DATA DIAGNOSTICS
In case of failure of the internal memory or corruption of programmed data, just after switching on, Ech appears with the
relevant Fault contact signal.
In this case, for safety reasons, the default parameters are loaded automatically (see programming table on pages 13-14).
Eliminate the Ech indication by pressing RESET and run programming to enter the desired values.
Finally switch the unit off and back on to check the memory works correctly, if it is damaged Ech will be displayed again
(send the control unit to TECSYSTEM srl for repairs).
TEMPERATURE DIAGNOSTICS
When one of the thermometers detects a temperature higher than 1 ° C with respect to the pre-set value as the alarm limit,
after approximately 5 seconds the ALARM relay switches and the channel ALARM LED (CHn)switches on.
When the trip temperature limit is exceeded, after approximately 5 seconds the TRIP relay switches and the channel TRIP
LED (CHn) switches on.
As soon as the recorded temperature returns to values equal to or lower than the limit set for the ALARM and TRIP relays
switching, these relays de-energise and the corresponding LEDs switch off.
The values of ALARM andTRIP are kept in the internal memories: they can be recalledby entering theVis modes (displaying
programmed parameters) and modifiable in the PRG mode (programming).

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NT935 WS EVO
COOLING FAN CONTROL
The NT935 WS EVOcontrol unitis fitted with two FAN contacts (FAN1 and FAN2) and, if programmed correctly, can control
the fans switching ON and OFF to cool the transformer.
The FAN1 and FAN2 contacts can manage cooling of the transformer and the room where it is installed: the cabin.
By connecting FAN1 to the tangential ventilation system (the two bars on the transformer) and FAN2 to the extractor, you
will improve the air flow in the cabin; moreover, the cabin temperature will no longer need to be managed by a thermostat
outside the system.
The fans can be controlled in two different ways:
• Using the temperatures sensed by the sensors on the three columns (FAN1)
CHF 1.2.3
(e.g.. ON at 70°C - OFF at 60°C)
• Through an additional sensor (CH4/YES) dedicated to the ambient temperature inside the transformer room (FAN2).
CHF 4
(e.g.. ON at 45°C - OFF at 35°C)
The ON and OFF values are programmable according to the device range. The FAN ON must always be at least 1°C higher
than FAN OFF (recommended ΔT FAN ON_OFF +10°C).
The FAN 1/ 2 LED lights up when the temperature exceeds 1°C the FAN ON threshold, the corresponding relay switches,
and turns off when the temperature goes below 1°C the FAN OFF threshold, the corresponding relay switches.
.
FAN TEST
It is possible, by programming (HFn), to make sure that the fans are operated for 5 minutes every xxx” hours, regardless of
the temperature values of the columns or the environment (e.g.: with HFn = 001 the fans are activated for 5 minutes every
hour).
This function is designed to periodically check the operation of the fans and of their control equipment.
Setting NO, this function is inhibited.
To enable the HFN function, read the programming section on pages 13-14.
INTELLIFAN FUNCTION
What is it for:
The Intellifan function is used to reduce the thermal shock on the transformer by partially bringingforward (one bar at a time)
activation of the tangential ventilation system.
The reduction in the transformer's thermal shock will extend the life of the transformer and of the ventilation system itself.
By enabling the FAN1 "INT" function, the control unit will alternate the activation (each 30 minutes) of the FAN1 and FAN2
contacts, anticipating the activation ofthe ventilation system at the intermediate value included between FAN1 ON and FAN1
OFF.
ES. FAN1 ON = 70°C and FAN1 OFF = 60°C ACTIVATION FAN INT. = 65°C
Before enabling the function, check that the connection of the two ventilation bars is distributed in such a way that the RH
bar is connected to the FAN2 relay, pins 1-2, and the LH bar is connected to FAN1, pins 3-4.
By selecting FAN1 "NO or YES", the function will be disabled.
once the FAN1 threshold is exceeded, the control unit will activate both bars.
To enable the INTELLIFAN function, read the programming section on pages 13-14.
For correct operation of the INTELLIFAN function it is advisable to respect ΔT 10°C between FAN1 ON and FAN1
OFF. The connection to the VRT series devices, where Intellifan is enabled, must be made between the contacts
FAN1 - COM-EN1 and FAN2 - COM-EN2.
IMPORTANT INFORMATION
Before carrying out the isolation test of the electrical panel the control unit is installed on, disconnect it together
with the sensors from the power supply to prevent it from being seriously damaged.

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NT935 WS EVO
TECHNICAL SPECIFICATIONS OF THE EXTENSION CABLE
FOR Pt100
1. Cable 20 x AWG 20/19 Cu/Sn
2. Section 0.55 mm²
3. Flame-protection insulation PVC105
4. Standards CEI 20.35 IEC 332.1
5. Maximum operating temperature: 90°C
6. Configuration: 4 triples of three twisted and coloured conductors
7. Screen on Cu/Sn
8. Fireproof PVC sheath
9. Outer diameter 12 mm
10. Standard configuration in 100 m coils
The NT935 WS control unit has the selection n.o (normally open contact) / n.c (normally closed contact) for the ALARM, TRIP
and FAULT relays, programming steps from 30 to 35 page 14. Selecting the YES/NOsetting introduces the Fail Safe and No
Fail Safe functions.
ALARM AND TRIP
By setting NO (NO Fail safe) the normally open contacts are in positions 5-7 Alarm and 8-10 Trip, they switch only when the
pre-set temperature limits are reached.
By setting YES (Fail safe), the normally closed contacts are in positions 5-7 Alarm and 8-10 Trip, they switch only when the
pre-set temperature limits are reached or as a result of no voltage.
FAULT
By setting YES (Failsafe), contact 11-12 is positioned as normally open, switches (closed) when a fault condition is identified;
see paragraph on alarms and ventilation on page 12.
Setting NO (NO Fail safe) the contact 11-12 is positioned as normally closed, switches (open) when a fault condition is
identified; see paragraph on alarms and ventilation on page 12.
If the fail safe function is disabled on the fault contact, the control unit will no longer be able to signal the fault due to power
failure. In this case it is advisable to enable the Fail safe on the ALARM contact for the afore-mentioned indication.
NOTE: when the control unit is in one of the modes indicated below, it does not perform any thermal monitoring, moreover
the relays will all be disabled the FAULT LED will flash.
• Vis. display programming.
• PRG programming.
• Test of the relays.
The FAIL SAFE function is temporarily disabled and the FAULT relay switches.
ATTENTION: accessing at the relay test mode will temporarily disable the failsafe function, the relays with function
enabled switch (ALARM-TRIP-FAULT).
FAIL SAFE FUNCTION

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NT935 WS EVO
The NT series equipment boasts an innovative control function combined with the dynamic status of the Pt100 sensor.
Activating FCD, the control unit analyses the increase in temperature ∆T (*) recorded in a second (°C/sec).
Enabling the function, the user can select the value (ΔT) from a minimum of 1°C/sec up to a maximum of 30°C/sec. If the
measured value is higher than the value set by the user, the control unit inhibits any activation of the ALARM and TRIP
alarms and activates the switching of the FAULT relay (11-12), signalling on the display "fault for Fcd".
e.g. setting the function to 5°C, the fault switching for FCD will only be activated if the control unit detects an increase ΔT
higher than 5°C in one second on the monitored system.
Setting "no" the FCD function is disabled.
When a channel is in Fault for FCD, the relative alarm and trip signals are inhibited on the single channel; therefore only
the anomaly of excessively rapid increase of the temperature is signalled.
Press Reset to cancel the FCD signals of all the channels and reset the relay fault.
Possible applications of FCD
Identification of a possible induced interference on the Pt100 sensor line
If the installation instructions are not complied with (see page 15), any interference on the Pt100 sensor line can cause
false readings or anomalous alarms.
Setting the FCD function in a temperature range of between 1°C and 10°C (5°C recommended), the effects caused by
false readings can be suppressed and the alarm relay activation can be prevented, as shown above.
Corrective actions: check the installation of the sensor extensioncable is in line with the instructions given in the paragraph
on the measurement signal transfer on page 15.
Identification of a sensor fault or faulty connection
In case of a faulty connection or sensor fault, a quick positive or negative variation in temperature might occur, leading to
the system tripping or the alarms of the monitored system to be triggered.
In this specific case we recommend the FCD function to be set in a temperature range of between 10°C and 20°C.
Corrective actions: check the terminals the sensor is connected to are tightened and replace the faulty sensor, if required.
Identification of the electrical motor rotor block
In case of temperature control of the electrical motors, the quick temperature increase might be due to a blocked rotor.
In this specific case, it is advisable to set the FCD function in a temperature range of between 20°C and 30°C.This setting
is recommended in order to avoid activation of the FCD function during the motor starting phase, i.e. where the increase
ΔT/sec. has a very rapid variation.
(*) The ΔT value shows the temperature range for each second.
NOTE: it is advisable not to enable the FCD function with VOTING active.
FCD FUNCTION
NT935 WS EVO WI-FI CONNECTION
The NT935 WS EVO control unit has a built-in WEB SERVER that is accessible via Wi-Fi connection.
What is needed to access the NT935 WS EVO control unit?
To access the web server a device with a Wi-Fi connection and an Internet browser is needed.
How to connect on the first start? “Access Point” mode
Power the control unit by keeping the button on the back pressed
for approximately 5 seconds.
NOTE: Access point key
The access point key allows the user to temporarily access the web server in the
"Access Point" mode, forcing operation with the IP address 192.168.8.8.
How it works:
With the control unit off, keep the access point button pressed, then power the
device and release the button after approximately 5 seconds

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NT935 WS EVO
Launch the search for Wi-Fi networks from your device (PC, Smartphone or Tablet).
NOTE: the name of the network to connect to consists of: TECSYSTEM followed by the serial number S/N of the device and
the year of production (20 = 2020), valuesshown on the identification label of the product purchased.
Select the TECSYSTEM (S/N + YEAR) network.
Click on CONNECT
The TECSYSTEM network requires the insertion of a digital network key: TECSYSTEM in the network key window, repeat
the operation in the network key confirmation window.
Click on CONNECT
Once the connection is established, your device will indicate Connected TECSYSTEM.
NOTE: Connecting to the NT935 WS network will result in automatic disconnection from other networks; for devices such as
Smartphones or Tablets it may be necessary to disable the data connection.
Having connected to the TECSYSTEM network (S/N + YEAR) open your browser program and type in the address
192.168.8.8, that follows on page 21.
TECSYSTEM (S/N + YEAR)
TECSYSTEM (S/N + YEAR)
TECSYSTEM (S/N + YEAR)
TECSYSTEM…