Tekmar 1873-ESM Guide

Ice and Snow Detector
1873-ESM and 1875-ESM
Installation and Adjustment Instructions
1873-ESM
1875-ESM

2
Content
Scope of delivery ..........................................3
Overview.......................................................4
Terms and functions .....................................7
Installation and commissioning...................16
Connection diagrams........................... 17
Required settings.................................24
Further basic settings...........................25
User interface 1873..................................... 29
Menu: Single Unit.................................31
Menu: System...................................... 34
Menu: Multi Channel............................40
Troubleshooting.......................................... 74
Technical data.............................................83
Available accessories .................................86
Safety instructions
Always observe the attached safety instructions and
the general regulations for electrical installation
during installation and operation of the device!

3
Scope of delivery
Ice and Snow Detector
1873-ESM or
1875-ESM
Installation and Adjustment Instructions
Ice and Snow Detector
1873-ESM and 1875-ESM
Safety instructions
tekmar pencil (only 1873-ESM)
(Rubber end can be used to operate the touch
display)

4
Overview
Tekmar ice detection systems use their combi sen-
sors to measure temperature and moisture in
heated outdoor areas such as open spaces, roofs
and gutters. This means that they operate in a par-
ticularly energy-efficient way, since the heating is
only switched on when it is cold or if there is water,
ice or snow.
The 73 ice detection system is an all-round system
to be used wherever it is necessary to keep an area
free of ice and snow: It is flexible, maintenance-free
and inexpensive. It can be modularly extended to
form a multi channel system and can be used in a
cloud environment or in building management sys-
tems.
All system 73 control devices are easy to install and
commission. They are characterised by intelligent
factory settings and a straightforward commission-
ing function. The sensors and the control units can
be freely combined so that the system can be opti-
mally adapted to the operating conditions. All con-
trol units are designed for one combi sensor and
one heating circuit.
Configurations
The basic 1873 device can either be used as a
single unit or as a basis for setting up an ice
detection system with one or several channel(s)
and communication with the building management
system or the tekmar Internet Server.
A single-channel system consists of a basic device
in combination with a combi sensor and a heating
circuit. It can be extended with an Internet or
Modbus Gateway, so that remote control, monitor-
ing and maintenance can be carried out via the
central building management system or the
platform-independent user portal of tekmar's TAV
Server (“Tekmar Anlagen Verwaltung”, Tekmar
System Management).
If required, the System 73 can be expanded to a
multi channel system with up to eight sensors and
heating circuits using the 1875 extension unit. The
heating circuits can be assigned to up to four
different zones, which have a separate pre-heating
and base temperature mode and individual week
time programs as well as a holiday program. The
sensors of a zone can be coupled to one signalling
circuit in which one of the sensors activates all

Overview
5
heating circuits of the channels belonging to the
zone.
Ice and Snow Detector 1873-ESM
The Ice and Snow Detector 1873 is a single-
channel basic device that can be used for all
applications in the field of ice and snow detection.
With the 1875 extension unit and the 1880 gate-
ways, the 1873 can be expanded into multi-
functional systems with up to 8 sensors/heating
channels and connection to the internet or a build-
ing management system.
It is operated and adjusted via an illuminated touch
graphic display, which is also used to set the para-
meters of all the other devices in a system. The
multilingual menu with three-level password protec-
tion automatically adapts to the selected configura-
tion (Single Unit, System or Multi Channel).
In addition to the basic functions of the ice detection
channel, the 1873 has a zone management system
that allows the device's own channel and the ice
detection channels of the extension units to be cen-
trally controlled via optional functions in up to 4
zones.
A comprehensive alarm management checks both
the internal device functions and those of the con-
nected sensors. Furthermore, the function of the
heating relay and a downstream contactor can be
monitored.
Ice and Snow Detector 1875-ESM
The 1875 extension unit, in conjunction with a 1873
basic unit, permits the modular design of multi-
channel systems with up to 8 ice detection chan-
nels. The 1875 is operated and set via the touch
graphic display of the 1873.
The 1875 ice detection channel can be integrated
into the zone management of the 1873 and can
thus participate in all control functions within a sys-
tem. This also applies to alarm management and
the gateway functions with regard to the internet or
to the building management system.
The functions of the ice detection channel of the
1875 are identical to those of the 1873.
Sensors
The System 73 sensors use a measuring principle
based on the thermal capacity of the sensor surface
and the water on it, possibly in the form of ice or

Overview
6
snow. This measuring principle was developed by
tekmar and has already proven itself over many
years. Only one sensor is required to measure
moisture and temperature, making installation very
simple and cost-effective.
System 73 offers two types of sensors: The 3356
sensor is ideally suited for installation in open
spaces such as roads, walkways or staircases. The
3354 sensor can be mounted, for example, in
gutters and on roof surfaces thanks to its design
with axial cable connection. Both sensors are
characterised by a compact and robust design,
which is achieved by the casing made of high-
quality, corrosion-resistant brass and the microbe-
proof, longitudinally watertight cable.
The sensors can be used for a wide variety of re-
quirements due to the comprehensive range of
accessories for their installation and mounting. This
also optimises installation and maintenance costs.
Documentation
Other relevant documentation:
Safety instructions
I-187x-ESM-Sensor-EN,
summarised extract from M-MES-Sensorik
(Installation instructions for sensors of the T,
TF-E und TF-S systems, available in German
only)
Gateway Internet 1880/(W)LAN-GWI:
Installation and Adjustment Instructions
Gateway Modbus 1880/D85-GMR/UNI:
Installation and Adjustment Instructions

7
Terms and functions
Application
The basic unit 1873 can be set to three different
complex configurations. These are called applica-
tions and are as follows:
Single Unit refers to the use of a single 1873 to
which no other devices are connected. An 1873
used as a Single Unit has an ice detection
channel, but no zone for further control options.
A System is an 1873 with zone functions, which
can be optionally extended by a communication
device to tekmar's TAV Server on the internet
(Internet Gateway) or to the building manage-
ment system (Modbus Gateway). An 1873 used
as a System has an ice detection channel and a
zone for further control options.
A Multi Channel system is a combination of an
1873 and several 1875 devices, which can be
optionally extended by a communication device
to tekmar's TAV Server on the internet (Internet
Gateway) or to the building management system
(Modbus Gateway). The system has up to 8 ice
detection channels that can be combined and
controlled in up to 4 zones.
In addition to the internal functions, the application
settings also optimise the menu so that only those
settings that are relevant for the selected applica-
tion are displayed.
Ice detection channel
An ice detection channel is a unit consisting of a
heating circuit with its output relay, a combi sensor
and the associated evaluation logic. The 1873 and
the 1875 each have an ice detection channel. By
combining an1873 and up to seven 1875 devices,
multi channel systems with up to eight ice detection
channels can be set up.
Functions of an ice detection channel:
control and monitoring of one sensor and one
heating circuit
continuous temperature monitoring in the heated
area
activation of the moisture measurement if the
temperature falls below the activation tempera-
ture
start of the minimum heating time if the moisture
threshold is exceeded on the sensor (alterna-
tively triggered by an external signal at the con-
trol input)

Terms and functions
8
deactivation of the heating if the temperature
falls below the switch-off temperature (lower
temperature limit)
monitoring of the heating circuit output for inter-
ruptions in the heating circuit and internal faults
of the relay
optional base temperature mode in order to pre-
heat an open space in the "System" or "Multi
Channel" configuration
In a multi channel configuration, the 1875's ice de-
tection channels are automatically registered with
the 1873's zone management within minutes after
power-on.
All registered channels are alternately displayed in
the idle display and listed with their channel number
in the list of registered channels. If a registered
channel is not available for too long, it is marked as
"offline" and an alarm is triggered.
If a channel was known in the zone management
once, it is permanently stored. If an 1875 is re-
moved from the configuration, it must be explicitly
deleted from zone management via a menu func-
tion.
Operating mode
The basic operation of an ice detection channel can
be selected via the operating mode.
Temp. Moisture
This is the normal operating mode of an ice de-
tection channel. In this mode the temperature
must first fall below the activation point, and a
sufficiently high moisture measurement then
activates the heating circuit. If channel coupling
is used, the moisture measurement of another
sensor in the zone may also activate the heating
circuit.
T Moi+BaseTemp
With regard to temperature and moisture
measurement, the channel operates as
in normal operation, but activates the base
temperature mode if the base temperature is not
reached.
Temperature
In the temperature mode, only the tem-
perature is measured but not the mois-
ture. The heating will be active if the
temperature of the heating area is below the ac-
tivation temperature.

Terms and functions
9
Emergency mode
In addition to the automatic activation of
the emergency mode, it can also be
activated manually in the event of malfunctions
around the system. Also refer to the explana-
tions under "Emergency mode" on page 11.
Off
The ice detection channel is switched off.
Activation temperature (upper temperature limit)
If the temperature of the combi sensor - and thus of
the heated area - falls below the defined activation
temperature, the moisture measurement will be ac-
tivated and, if necessary, the heating circuit will be
switched on. If the temperature rises above the
activation temperature, an activated heating circuit
will be switched off and the moisture measurement
will be deactivated.
Moisture threshold
The moisture threshold can be used to adjust the
sensor's sensitivity with regard to the detection of
water, ice or snow on the sensor. The moisture
threshold can be set within a range of 0.5 to 9.5.
Low values mean high sensitivity.
The basic setting for the moisture threshold should
be 1 to 2 points above the dry value indicated on
the sensor. If no information is available on the
sensor, a test measurement can be triggered via
the menu when the sensor is dry and the deter-
mined value can be used as the dry value.
If the system switches the heating system on too
early, i.e. if there is very little moisture or the sensor
is dry, the moisture threshold should be increased.
If the system switches on the heating system too
late, the moisture threshold should be reduced.
Note: If the moisture threshold is too low, the
heating system may be permanently
activated during times when the temperature is be-
low the activation temperature. This can lead to an
increased energy consumption. In general: the
lower the moisture threshold, the higher the energy
consumption.
Moisture measurement
Below the activation temperature, the moisture
measurement is repeated at regular intervals until a
moisture value above the moisture threshold is de-
tected or until the activation temperature is
exceeded again. If moisture is detected, the heating

Terms and functions
10
circuit switches on for the minimum heating time
and the moisture measurement is suspended. Only
after the minimum heating time has elapsed is the
moisture determined again at regular intervals. De-
pending on the result of the moisture measurement,
the heating circuit remains switched on or is
deactivated.
The system automatically optimises the duration of
a measuring cycle depending on the sensor type
and temperature.
Switch-off temperature (lower temperature limit)
In addition to the activation temperature, there is
also a lower temperature limit (the switch-off tem-
perature), below which the moisture measurement
and, if necessary, the heating are deactivated
again.
At very low outside temperatures, dripping conden-
sation no longer occurs in roof areas and snowfall is
no longer to be expected in open spaces. (If snow
falls, it will be dry, light and not slippery. Since in
this case the heating capacity is often not sufficient
to completely defrost the surface and it would only
be partially thawed instead, the risk of slipperiness
would be rather increased by switching on the heat-
ing system.)
Minimum heating time
If moisture above the moisture threshold is detected
after the temperature has fallen below the activation
temperature, the minimum heating time starts,
which ensures that the heated area is definitely de-
frosted. During the minimum heating time, no
further moisture measurement takes place.
An external button on input A, which is switched to
L, can be used to manually activate the defined
minimum heating time. When the button is pressed
once, the heating is switched on for the duration of
the minimum heating time.
Follow up time
After the monitored area has thawed and dried with
the help of the heating, i.e. when the combi sensor
no longer detects moisture, a follow up time can be
activated. In the event that the combi sensor cannot
be optimally positioned, the follow up time can be
used to ensure that any ice and snow residues are
also defrosted, e.g. in shaded areas.

Terms and functions
11
Base temperature mode
With the base temperature mode for an ice detec-
tion channel, the ground of an outdoor system can
be kept at an adjustable base temperature at low
outside temperatures (2-point control). This is use-
ful to shorten the time it takes for very slow heating
systems to reach a defrost and drying temperature
in case of moisture. The base temperature mode is
only possible in the "System" or “Multi Channel"
configuration and can be activated individually for
each ice detection channel via the "T 
Moi+BaseTemp" operating mode.
Note: To switch off the base temperature
mode in case of rising temperatures, it is
necessary to install an additional weather sensor or
to connect the system via the Internet Gateway to
the TAV Server to provide a weather forecast.
The lower temperature limit can be used to deacti-
vate the base temperature mode in case of very low
temperatures. At very low temperatures, the surface
might not be completely heated, so that the thawed
ice could freeze again, increasing the risk of
slipperiness.
Note: Depending on the weather conditions,
the base temperature mode can lead to very high
energy consumption.
Emergency mode
In the emergency mode the heating circuit output is
activated with a PWM (pulse width modulation) be-
haviour, in which the basic time and the duty cycle
can be set. The emergency mode can either be
activated manually via the operating mode or auto-
matically if there is a temperature error in the combi
sensor.
In case of an error in the combi sensor additionally
an alarm will be triggered. If only the moisture unit
is affected by the sensor error, the emergency
mode will only be activated if the temperature is
below the activation temperature. If the temperature
unit is also defective, the emergency mode will be
activated independently of the outdoor temperature,
but only if this has been explicitly enabled in the
menu.
Note: The emergency mode should only be
activated if the alarm can be registered cen-
trally. An unnoticed emergency mode can possibly
lead to extreme energy consumption.

Terms and functions
12
Zone
One or more ice detection channels can be
assigned to a zone, which then have extended
control options. When configured as a system, the
1873's ice detection channel is automatically
assigned to the only zone. The assignment of the
channels to the zones within a multi channel system
can be freely defined.
Zone management functions:
free assignment of an ice detection channel to
one of the 4 zones, function options can be
activated separately for each zone
pre-heating mode with air temperature sensor
for pre-heating all heating areas in a zone
channel coupling in order to interconnect all
sensors in a zone
week program to automatically set the operating
mode
common holiday program for all zones
Week programs
Each zone has its own week program. In a week
program a time control can be used to change the
control mode of the zone automatically in a daily
and weekly rhythm. A maximum of 16 switching
points can be defined for each week program.
Available control modes:
Channel: All ice detection channels in the zone
operate solely on the basis of their set operating
mode.
Channel + preHeat: Additionally a pre-heating
mode is activated for all heating circuits of the
ice detection channels.
Off: All ice detection channels are switched off.
An additional holiday program, which affects all
week programs, allows you to override the set week
programs for a period of time, e.g. company holi-
days.
The time underlying the week programs must be set
manually (summer/winter time changeover is auto-
matic), provided the system is not connected to the
internet via the Internet Gateway.
Channel coupling
If several ice detection channels are assigned to a
zone, the channel coupling can be used to activate
an action grouping for all channels. When channel
coupling is used, all heating circuits of this zone are
activated as soon as one of the combi sensors of

Terms and functions
13
the zone reports a temperature below the activation
temperature together with a moisture value above
its moisture threshold.
Pre-heating mode
The pre-heating mode, like the base temperature
mode, allows heating of an open area even before
moisture is detected. In contrast to the base tem-
perature mode, however, the pre-heating mode
operates with PWM performance control based on
the measured or predicted outdoor temperature.
The pre-heating mode is a zone function that af-
fects all assigned ice detection channels of the
zone. Note: The base temperature mode of a
channel has priority over the pre-heating
mode. If both pre-heating and base temperature
mode are set for a channel, the pre-heating mode is
automatically inactive.
The pre-heating mode operates within the parame-
ter limits "start temperature" and "end temperature",
which represent the upper and lower temperature
limits. Both values are pre-defined with useful
values, but can be adapted to local conditions if
required.
The PWM performance at the start temperature is
defined via the "start value”. The performance at
the end temperature is always 100%. The heating
capacity is adjusted linearly between the start and
end temperature.
The lower temperature limit is used to deactivate
the base temperature mode in case of very low
temperatures. At very low temperatures, the surface
might not be completely heated so that the thawed
ice could freeze again, increasing the risk of
slipperiness.
Note:
Pre-heating is activated via the week program of
the zone by setting the "Channel + preHeat" control
mode.
If the system is run in the „Multi Channel“ applica-
tion also option "Time control" of the respective
zone has to be activated. In the "System"
application the time control is always active.
For the pre-heating mode either a weather sensor
or - even better, because it is connected to the
weather forecast - an Internet Gateway with
connection to the TAV Server must be available to
determine the air temperature.

Terms and functions
14
Note: Depending on the weather conditions,
the base temperature mode can lead to very
high energy consumption.
Weather sensor and weather forecast
For the base temperature and pre-heating mode,
the system must have information on the outside air
temperature. This requires either an outdoor
weather sensor (north side, no direct sunlight) or a
weather forecast that the system receives from
tekmar's TAV Server via the Internet Gateway. Both
sources are evaluated independently of each other
as a single value and as far as possible as a time
series. If both sources are equally available, the
weather forecast has priority for determining the
effective outdoor temperature, as it enables a pre-
dictive calculation of the heat demand.
With two parameters the calculation of the heat
demand of the open area can be adapted to the
local conditions. The "ground characteristic" takes
into account the inertia of the open area with re-
spect to changes in the ambient temperature. It
thus takes into account the past outside
temperatures for calculating the effective outside
temperature. The "heat-up characteristic" is the
speed at which the open area can be heated via the
heating circuit.
Alarm management
The alarm management of the 1873 monitors all
devices, sensors and heating circuit outputs in a
system for fault conditions. A detected error is re-
ported via the display and the alarm relay and can
be forwarded to a higher level via the Modbus
Gateway.
Functions of alarm management:
monitoring of all ice and snow detectors and
their sensors in a system
monitoring of all heating circuit outputs in a
system
alarm function can be deactivated for each zone
adjustable alarm delay
forwarding of an alarm via the alarm relay and/or
the Modbus Gateway
Alarm relay
The alarm relay is designed as a change-over con-
tact and can therefore be used for both open-circuit
and closed-circuit alarm circuits. By inverting the
alarm relay in the menu, a power failure can also be

Terms and functions
15
reported (alarm inverted and signal loop via the
normally open/change-over contact).
Due to its insulation, the alarm relay can be used
for both mains voltage and SELV circuits.
Heating circuit monitoring
The heating circuit connected to the heating circuit
relay is monitored for interruptions and the heating
relay itself for malfunctions. The heating circuit is
monitored when switched off. An interruption of the
circuit results in an alarm message.
Note 1: When using a contactor to increase the
switching capacity, only the contactor is monitored,
not the heating circuit connected to it.
Note 2: The switching output for relay R1/R2 must
be operated at 230 V to detect a switching output
error. When using a lower voltage (e.g. 24 V DC),
this function is not guaranteed and an error
message may occur.

16
Installation and commissioning
Proper use
The device must only be used for the control
of electric and water-operated heating
systems. It has to be installed in an electric
distributor (fuse box or control cabinet) and con-
nected to the existing heating system. When doing
so, it is absolutely necessary to observe all Tech-
nical data. Any different or improper use of the de-
vice may cause defects in the device and/or life-
threatening states and situations. Additionally all
guarantee claims are forfeited in such a case.
Installation procedure
Only qualified personnel (electrician or
similar qualification) may install the device.
The relevant engineering practices and the
enclosed safety instructions must be observed!
Disconnect the control cabinet before installation.
Mount the device on a 35 mm mounting rail in a
subdistribution unit or another adequate housing.
Wire it according to the following illustration.
Protection against contact according to protection
class II is guaranteed by the following measures:
Installation in small distribution board according to
DIN 57603/VDE 0603 (e.g. distributor of the N-
system)
or
DIN 57659/VDE 0659
The regulations according to VDE 0100 must be
observed!

Installation and commissioning 1873, 1875
17
Connection diagrams
1873-ESM
1875-ESM

Installation and commissioning 1873, 1875
18
Connection of a downstream building control
system
It is intended to connect the heating circuit to a load
contactor or directly to the relay output of the ice
and snow detector. If, however, it is connected to a
relay interface module, a reliable function cannot be
guaranteed. This unintended application does not
always work reliably.
tekmar has, with no obligation, developed and
tested a solution for a correct function, also in
connection with a recommended relay interface
module for connection to a building management
system:
When using relay interface modules with the 1873-
ESM or 1875-ESM ice and snow detector, a mal-
function of the heating circuit monitoring can occur
under certain circumstances due to the design. This
leads to a faulty evaluation of the heating circuit or
a malfunction of the connected relay interface mo-
dules. The faulty evaluation can result in an unin-
tentional alarm. However, it would be more serious
if the heating circuit(s) were unintentionally acti-
vated, which would lead to increased power con-
sumption.
This kind of relay is normally only used in case of a
downstream building management system.
For the recommended relay interface modules, pro-
per function is only ensured if a base load element
is connected in parallel with the relay interface mo-
dule. In addition, the heating circuit monitoring func-
tion (menu item Monitoring heating output acti-
ve) of all channels with a connected relay interface
module must be deactivated in this case.
Recommended components:
Relay interface module
Manu-
facturer
Article
Type
Finder
38.51 230V (Series 38)
1 x 6 A
Finder
48.52 230V (Series 48)
2 x 8 A
Finder
49.72 230V (Series 49)
2 x 8 A
Base load device
Eltako
EAN 4010312900970

Installation and commissioning 1873, 1875
19

Installation and commissioning 1873, 1875
20
Connection via TGN
When several devices in a system are connected, they all need to be connected to each other via the TGN
bus so that they can exchange data with each other.