Licht MFC-300/T-Dry User manual

Temperature Controller
model MFC-300/T-Dry
Version for Dry Transformers
Technical Manual
Licht

Rev. A1 (30–05–12) MFC-300/T-Dry Technical Manual 1
Contents
1 Introduction 2
2 Operating principle 3
2.1 General principle 3
2.2 RTD operation 3
3 Front panel indication 5
4 Configuration 6
4.1 Parameter reset 6
5 Programmable parameters 7
5.1 Current outputs (option) 8
5.2 MODBUS protocol 9
5.3 DNP3 protocol (option) 9
5.4 Clock 10
6 Additional versions 11
A Specifications 12
B Housing diagrams 13
C Weatherproof enclosure layout 16
D Connection diagrams 17
E MODBUS registers 20

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Rev. A1 (30–05–12) MFC-300/T-Dry Technical Manual 2
1 Introduction
The MFC-300/T-Dry is a precise, highly reliable and versatile microcontrolled system for
power transformer temperature control. It is designed to read, infer, display and transmit
the temperatures of up to 6 RTDs (resistance temperature detectors), and to activate
alarm, cooling and shutdown systems whenever necessary.
Among its features, we highlight: up to 6 compensated and auto-calibrated RTD inputs
for temperature measurement, 1 isolated RS-485 line, independent relays for cooling,
alarm, trip and failure, independent set-points for cooling, alarm and trip and up to 6
current loop outputs (one for each input). Versions with up to 12 relays may be supplied
on special order.
The temperature acquisition is performed with 16-bit resolution. All DC signals are
sampled after a 50/60 Hz filter with a rejection band attenuation greater than 100 dB.
The MFC-300/T-Dry presents pairwise galvanic isolation between signal inputs, power
supply, current outputs and the RS-485 port. It features a universal 80-260 Vdc/Vac
power supply.
The MFC-300/T-Dry shares its hardware and form factor with other Licht controllers for
transformers, such as the MFC-300/R voltage regulator and the MFC-300/P parallelism
controller. All signals that enter and exit the controller are pairwise galvanically isolated,
preventing potentially damaging noise and transients from being transferred between sub-
circuits or retransmitted to other devices.
Figure 1.1 MFC-300/T-Dry Controller (96x48 version)

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Rev. A1 (30–05–12) MFC-300/T-Dry Technical Manual 3
2 Operating principle
2.1 General principle
The MFC-300/T-Dry’s main purpose is to monitor transformer temperatures and acti-
vate cooling systems whenever necessary. It features up to 6 RTD inputs, which are
automatically compensated for cable length and linearized for each sensor’s standardized
temperature response.
The standard MFC-300/T-Dry configuration for dry transformers features 4 relays, as-
sociated with cooling, alarm, trip and failure events. Each RTD has associated cooling,
alarm and trip set points. For instance, if the cooling set point associated with RTD 2 is
configured to 80 ◦Cand this RTD’s temperature exceeds this value, the MFC-300/T-Dry
activates the forced cooling relay, regardless of the states of the other RTDs.
Each relay features a hysteresis, whose purpose is to prevent intermittent activations
whenever the temperature oscilates around a configured set point. For example, if the
cooling hysteresis is configured to 2 ◦C, then in the example above the cooling relay will
only be deativated once RTD 2’s temperature drops below 80 −2 = 78 ◦C.
Relays dedicated to cooling functions may also be activated once per day at a configurable
time and remain active for a configurable duration. The daily activation of cooling pumps
or fans is desirable in cold climates in order to keep mechanical parts well lubricated and
to prevent the accumulation of dirt.
During normal operation, the temperature maximum for each RTD is registered in non-
volatile memory. These values may be reset with a user command.
The MFC-300/T-Dry can feature up to 6 current loop outputs with a 16-bit resolution
(one for each RTD measurement), and with scales configurable to 0-1, 0-5, 0-10, 0-20 or
4-20 mA.
2.2 RTD operation
The MFC-300/T-Dry continuously monitors the state of each RTD and its connection,
and automatically ignores sensors which are absent or which present abnormal behavior.
If the user wishes to install less RTDs than the maximum allowed by the equipment, the
parameter Qty. of Active RTDs should be set.
The following events are identified as RTD faults:

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Rev. A1 (30–05–12) MFC-300/T-Dry Technical Manual 4
.Measured temperature below 0 ◦Cor above 255 ◦C.
.Temperature variation rate exceeding 20 ◦C/s.
.Detection of inconsistencies in the measurement circuit.
Any of the events above triggers the activation of the RTD fault relay, the activation of
the cooling relay and the inhibition of future relay operations associated with the faulty
RTD. Once the originating fault is resolved (for example, by replacing a damaged RTD),
the system returns to normal operation after a 30 second delay.

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3 Front panel indication
During normal operation, the MFC-300/T-Dry alternates between displaying each chan-
nel’s value. The type of indication can be chosen between Temperature and Resistance.
In the Temperature display, the presented values are those measured by the RTDs, com-
pensated for each sensor’s intrinsic nonlinearity and cable resistances. The Resistance
option presents the physical RTD resistances read by the MFC-300/T-Dry in Ω, (without
the cable resistances).
The indication type can be temporarily altered by pressing the ↑and ↓keys.
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MULTI FUNCTION CONTROLLER
MFC-300/T/6
R 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 R 9 R 10 R 11 R 12 R 13 R 14
C
P
RTD 1: 63.0 C
RTD 2: 86.4 C
Figure 3.1 Front Panel

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4 Configuration
The MFC-300/T-Dry features 4 keys to access its functions. The procedure to configure
any parameter is as follows:
1. Press the Pkey to enter the parameters menu.
2. Enter the currently configured 4 letter password one letter at a time, using the ↑
and ↓keys to select each letter and Pto advance between letters. The default
password is AAAA.
3. Using the ↑and ↓keys, choose the desired parameter.
4. Press Pto confirm the parameter’s selection.
5. Choose the desired value with the ↑and ↓keys.
6. Confirm pressing P.
By holding down the ↑or ↓keys it is possible to advance through the options faster.
The configuration sequence can be cancelled at any time by pressing C.
4.1 Parameter reset
The MFC-300/T-Dry can be reset to factory settings. This procedure also resets its
password to AAAA. To do so, power up the device while pressing C.

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Rev. A1 (30–05–12) MFC-300/T-Dry Technical Manual 7
5 Programmable parameters
The MFC-300/T-Dry was developed to provide the user with the greatest possible flex-
iblity, such that all supervision and configuration can be executed on-site through the
keyboard or remotely via the RS-485 link.
We define all user-configurable parameters as follows.
Parameter:Fan Set Point [1-6]
Options: 0 to 255 ◦C, in increments of 1 ◦C.
Description: Temperature set point for activating the cooling relay associated with each
RTD.
Parameter:Alarm Set Point [1-6]
Options: 0 to 255 ◦C, in increments of 1 ◦C.
Description: Temperature set point for activating the alarm relay associated with each
RTD.
Parameter:Trip Set Point [1-6]
Options: 0 to 255 ◦C, in increments of 1 ◦C.
Description: Temperature set point for activating the trip relay associated with each
RTD.
Parameter:Indication Type
Options: Temperature, Resistance.
Description: Type of values indicated on the MFC-300/T-Dry’s front panel.
Parameter:Number of Active RTDs
Options: 1 to 6.
Description: Quantity of installed RTDs.
Parameter:Fan Hysteresis
Options: 1 to 255 ◦C, in increments of 1 ◦C.
Description: Temperature hysteresis for the deactivation of the cooling relay.
Parameter:Alarm Hysteresis
Options: 1 to 255 ◦C, in increments of 1 ◦C.
Description: Temperature hysteresis for the deactivation of the alarm relay.

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Parameter:Trip Hysteresis
Options: 1 to 255 ◦C, in increments of 1 ◦C.
Description: Temperature hysteresis for the deactivation of the trip relay.
Parameter:Fan Delay
Options: 0.1 to 25.5 minutes, in increments of 0.1 minute.
Description: Delay for the activation of the cooling relay.
Parameter:Alarm Delay
Options: 0.1 to 25.5 minutes, in increments of 0.1 minute.
Description: Delay for the activation of the alarm relay.
Parameter:Trip Delay
Options: 0.1 to 25.5 minutes, in increments of 0.1 minute.
Description: Delay for the activation of the trip relay.
Parameter:Daily Cooling (Start)
Options: 00:00 to 23:59, in increments of 1 minute.
Description: Time of day at which all cooling relays are forcefully activated. Use this
option to ensure the adequate lubrication of fans and pumps in cold climates.
Parameter:Daily Cooling (Duration)
Options: Disabled, or 1 to 999 minutes, in increments of 1 minute.
Description: Duration of the forced cooling cycle.
5.1 Current outputs (option)
Parameter:Output Scale
Options: 0-1, 0-5, 0-10, 0-20, 4-20 mA
Description: Refers to the various configurable current loop scales.
Parameter:TFS
Options: 0 to 255 ◦C, in increments of 1 ◦C.
Description: Full scale for the RTD temperatures. For example, if TFS = 150 ◦Cand
Output Scale = 4-20 mA, the displayed temperature will be 0 ◦Cfor 4.0 mA and 150 ◦Cfor
20.0 mA.

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5.2 MODBUS protocol
Parameter:Baud Rate
Options: 9600, 19200, 38400, 57600, 115200 bps.
Description: baud rate for the RS-485 link.
Parameter:Format
Options: 8N1, 8E1, 8O1, 8N2.
Description: symbol transmission format, where:
◦8N1: 8 data bits, no parity, 1 stop bit.
◦8E1: 8 data bits, even parity, 1 stop bit.
◦8O1: 8 data bits, odd parity, 1 stop bit.
◦8N2: 8 data bits, no parity, 2 stop bits.
Parameter:Address
Options: 1 to 247.
Description: MODBUS address for the MFC-300/T-Dry.
5.3 DNP3 protocol (option)
Parameter:Baud Rate
Options: 9600, 19200, 38400, 57600, 115200 bps.
Description: baud rate for the RS-485 link.
Parameter:Format
Options: 8N1, 8E1, 8O1, 8N2.
Description: symbol transmission format, where:
◦8N1: 8 data bits, no parity, 1 stop bit.
◦8E1: 8 data bits, even parity, 1 stop bit.
◦8O1: 8 data bits, odd parity, 1 stop bit.
◦8N2: 8 data bits, no parity, 2 stop bits.
Parameter:Address
Options: 0x0000 to 0xFFEF.
Description: DNP3 outstation address in hexadecimal notation.
Parameter:Application Layer Confirmation
Options: Only when transmitting events or multi-fragment responses, Always.

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Description: Selects when the MFC-300/T-Dry outstation should request application
layer confirmations.
Parameter:Maximum Inter-Octet Gap
Options: 2 to 100 ms.
Description: The DNP3 specification states that frames should not have inter-octet gaps.
In accordance, the MFC-300/T-Dry never inserts inter-octet gaps when transmitting data.
However, we allow the option to tolerate gaps in incoming transmissions. Frames featuring
inter-octet gaps larger than the Maximum Inter-Octet Gap will be quietly dropped.
Parameter:Backoff Delay (Fixed)
Options: 1 to 100 ms.
Description: See description for Backoff Delay (Random).
Parameter:Backoff Delay (Random)
Options: 1 to 100 ms.
Description: The MFC-300/T-Dry is designed for multi-drop scenarios where more than
one outstation may transmit over the same line. To handle collision avoidance, a backoff
scheme is implemented. Before transmitting, the MFC-300/T-Dry always waits for the
line to become idle. Once that happens, it waits for Tdelay =Tf ixed +Trandom ms, where
Tfixed is the fixed backoff delay and Trandom is a random value, uniformly distributed
between 0 and the random backoff delay parameter. If after Tdelay ms the line is still idle,
then the MFC-300/T-Dry begins transmission.
Parameter:Insert Inter-frame Gap
Options: Never, Always.
Description: The DNP3 specification states that no inter-frame gaps are required. How-
ever, some masters have been observed to drop frames when no inter-frame gaps are pro-
vided. This option allows communicating with such non-compliant devices. We discourage
its use, given that the forced inter-frame gap implies a forced backoff-delay.
5.4 Clock
Parameter:Date/Time
Options: HH:MM:SS DD/MM/YYYY
Description: sets the local date and time.

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6 Additional versions
Figure 6.1 MFC-300/T-Dry Controller (96x96 version)
Figure 6.2 MFC-300/T-Dry Controller (with weatherproof enclosure)

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A Specifications
Power Supply Isolated, 80-260 Vac/Vdc.
Power Consumption 8W
Operating Temperature -10 to 70 ◦C(LCD display)
-40 to 70 ◦C(VFD display)
Enclosure Rating IP20 (96x48 and 96x96 formats)
IP65 (with weatherproof enclosure)
Mounting Options Panel-mounted
Dimensions 96 x 96 x 190 mm or
96 x 48 x 190 mm
Weight 550 g
DC Inputs Types: RTD, current loop, voltage
Error/Non-linearity: 0.2% + 0.1% /10 ◦C
Current Outputs Scales: 0-1, 0-5, 0-10, 0-20, 4-20 mA
Error/Non-linearity: 0.2% + 0.1% /10 ◦C
Galvanic Isolation
(60 Hz, 1 min.)
Outputs 2.0 kV
Communication 2.0 kV
Communication RS-485 - MODBUS RTU or DNP3
9600, 19200, 38400, 57600, 115200 bps
8N1, 8E1, 8O1, 8N2
Displays 2 lines, 16 characters each (5 mm).
LCD with backlight or VFD.
Relays 10 A@ 250 Vac, 0.5 A@ 125 Vdc
Galvanic Isolation: 2.0 kV, 60 Hz, 1 min.

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B Housing diagrams

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C Weatherproof enclosure layout

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D Connection diagrams

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Important considerations
The installation of electronic devices in substations should conform with the recommen-
dations given by recent international standards. The most recent and detailed guide for
installations is IEC 61000-5-2:1997, which was based on decades of laboratory and field
research. We summarize below some of the guidelines contained in IEC 61000-5-2:1997.
For further reading, we recommend the articles and application notes available on our
web site.
a. Shielded cables must be used for connecting RTDs, current loop outputs, RS-485
links and the auxiliary supply.
b. Cables must be segregated in trays, ducts or conduits according to their functions.
In particular, power cables must never be routed in the proximity of signal cables,
even if these are shielded. The minimum distances which must be observed are
described in IEC 61000-5-2:1997 and in articles available on-line at this product’s
web page.
c. The electrical continuity of cables, ducts, trays and conduits must be preserved up
to frequencies in the order of MHz, over all their extension, including curves and
junctions. In order to guarantee this continuity, joints and bonds should present
electrical contact along each cable, duct or tray’s transversal section. In particular,
trays should be bonded with seam-welded joints (best), U-brackets with multiple
fixings (ok) and never with wires.
d. Shielded cables should present no gaps in their screens along their lengths. 360◦bond-
ing should be performed instead.
e. Should there be unshielded sections (for example, near terminal block connections),
these should be short as possible.
f. Trays, ducts and conduits must be electrically continuous, and must be grounded
at both ends. In this configuration, trays, ducts and conduits provide shielding
and also perform as parallel earth conductors.
g. Shielded cables should also have their screens bonded at both ends. It is extremely
important that the tray, duct or conduit which contains each cable is also grounded
at both ends, allowing it to perform as a parallel earth conductor. In the absence
of a parallel earth condutor, the cable screens will be exposed to extremely high
currents which will severely compromise their operation.
h. RS-485 pairs must be terminated at both ends by 120 Ωresistors.

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i. RS-485 devices must be connected in a bus topology. No other network topology
(tree, star, ring, etc.) is acceptable.
j. Dry contact inputs (if applicable) must free of potentials.