GHM-Messtechnik GREISINGER GMH 285 User manual

H69.0.01.6C-02
GHM Messtechnik GmbH • Standort Greisinger
Hans-Sachs-Str. 26 • D-93128 Regenstauf
+49 (0) 9402 / 9383-0 +49 (0) 9402 / 9383-33 [email protected]
as of version V1.0 GMH 285 / GMH 285-BNC
Operating Manual Pt1000 Precision Thermometer
For exchangeable probes, with alarm
WEEE-Reg.-Nr. DE 93889386
GMH 285
GMH 285-BNC
GMH-GREISINGER
GMH-GREISINGER

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
Index
1DESIGNATED USE....................................................................................................................................2
2GENERAL NOTE .......................................................................................................................................2
3SAFETY REQUIREMENTS......................................................................................................................3
4DISPLAY AND CONTROL ELEMENTS................................................................................................3
4.1 DISPLAY ELEMENTS .................................................................................................................................3
4.2 CONTROL ELEMENTS................................................................................................................................3
4.3 CONNECTIONS..........................................................................................................................................3
4.4 POP-UP CLIP .............................................................................................................................................4
5START OF OPERATION ..........................................................................................................................4
6SOME BASICS OF PT 1000 PRECISION TEMPERATURE MEASUREMENT..............................5
7CONFIGURATION OF THE DEVICE....................................................................................................6
8ADJUSTMENT............................................................................................................................................7
9ERROR AND SYSTEM MESSAGES......................................................................................................7
10 ACCURACY INSPECTION: ADJUSTMENT /UPDATE SERVICE................................................7
11 DISPOSAL NOTES..................................................................................................................................8
12 TECHNICAL DATA................................................................................................................................8
1 Designated Use
The device is measuring temperature in °C or °F.
A suitable Pt1000 temperature probe has to be connected for operation.
The safety requirements (see below) have to be observed.
The device must be used only according to its intended purpose and under suitable conditions.
Use the device carefully and according to its technical data (do not throw it, strike it, …).
2 General Note
Read this document carefully and get used to the operation of the device before you use it. Keep
this document within reach for consulting in case of doubt.
If the device is stored at temperatures above 50°C the battery has to be removed from the device.
NOTE: We recommend taking out battery if device is not used for a longer period of time.
Risk of leakage!

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3 Safety Requirements
This device has been designed and tested in accordance with the safety regulations for electronic devices.
However, its trouble-free operation and reliability cannot be guaranteed unless the standard safety measures
and special safety advises given in this manual will be adhered to when using the device.
1. Trouble-free operation and reliability of the device can only be guaranteed if the device is not subjected to
any other climatic conditions than those stated under "Specification".
If the device is transported from a cold to a warm environment condensation may cause in a failure of the
function. In such a case make sure the device temperature has adjusted to the ambient temperature
before trying a new start-up.
2. WARNING: If there is a risk whatsoever involved in running it, the device has to be switched off
immediately and to be marked accordingly to avoid re-starting.
Operator safety may be a risk if:
- there is visible damage to the device
- the device is not working as specified
- the device has been stored under unsuitable conditions for a longer time.
In case of doubt, please return device to manufacturer for repair or maintenance.
3. WARNING: Do not use these products as safety or emergency stop devices or in any other application
where failure of the product could result in personal injury or material damage.
Failure to comply with these instructions could result in death or serious injury and material
damage.
4 Display and Control Elements
4.1 Display elements
main display standard
Display of the current temperature
arrow up
arrow down
HLD
BAT
Display of maximum temperature
Display of minimum temperature
Display of Hold-value
BAT-Warning: pls. change battery
4.2 Control elements
key 1:
on/off key, press shortly: reactivate Backlight
key 2:
Mode
press shortly: minimum value
press again: maximum value
press again: return to standard display
press for 2 sec.: reset minimum and maximum values
key 3:
Hold:
press shortly: The current value is ‚frozen‘
(hold-function), ‘HLD’ is displayed
4.3 Connections
interface: connection for galv. Isolated interface adapter
(accessory: GRS 3100, GRS3105 or USB3100)
BNC-socket (GMH 285-BNC)
or 3.5mm audio socket (GMH 285):
Connection for Pt1000 temperature probe

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4.4 Pop-up clip
Handling:
•Pull at label “open” in order to swing open the pop-up clip.
•Pull at label “open” again to swing open the pop-up clip further.
Pop-up clip closed
Pop-up clip at position 90°
Pop-up clip at position 180°
Function:
• The device with a closed pop-up clip can be plainly laid onto a table or attached to a belt, etc.
• The device with pop-up clip at position 90° can be set up on a table, etc.
• The device with pop-up clip at position 180° can be suspended from a screw or the magnetic holder
GMH 1300.
Device attached to a belt
Device set up on a table
Device suspended from
magnetic holder
GMH 1300
5 Start of Operation
Switch the device on with the key . After segment test the device displays some information to
its configuration:
![ !F selected display unit (p.r.t. chapter 8)
0FFS if there is a offset adjustment (p.r.t. chapter 8)
S[AL if there is a slope adjustment (p.r.t. chapter 8)
P.OFF if the automatic-off-function is activated (p.r.t chapter 6)
The device starts measurement afterwards.

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6 Some Basics Of Pt 1000 Precision Temperature Measurement
Probe Precision/Device Precision
The device is very precise (please refer to technical data). To be able to use this high precision, the
connected temperature probe has to be as precise as possible, too. The following precision classes
are available as a standard at reasonable prices (Platinum resistor thermometers according to
EN60751):
Class Error ranges
B ± (0,3 + 0,005 • | Temperature |)
A ± (0,15 + 0,002 • | Temperature |)
AA (=1/3 DIN B) ± (0,1 + 0,0017 • | Temperature |)
Error over range –50...150°C
For applications demanding higher precision than given by this classes we suggest to adjust the
device to the used probe or to get a calibration certificate for the device combined with the probe.
Attention: if an adjusted or calibrated probe is replaced, also the adjustment or calibration certificate has to
be renewed to maintain the referring overall precision! Be careful when buying third party
temperature probes: Besides the standard EN60751 there are some other obsolete or unusual
standards on the market. If such a probe has to be connected, the user sensor curve (have a
look to the referring chapter) can be used to adjust the instrument!
2-Wire-Measurement
The GMH 285 uses 2 wire measurement, this means, cable and contact resistances may affect measurement precision.
For usual cables up to some meters the cable resistance is negligible. Keep contact clean and free from oxidation to
avoid contact effects.
Allowable temperature Range Of Probes
Pt100 Sensors are defined over a wide temperature range. Depending on probe materials and sort of sensor (e.g.
hybrid sensors, wire wound resistors...) the allowable temperature ranges have to be considered. Exceeding the ranges
at least causes a wrong measurement, it may even damage the probe permanently!
Often it also has to be considered, that the temperature range is just valid for the probe tube, (plastic-) handles can’t
stand the same high temperatures. Therefore the tube length should be selected long enough, that temperature keeps
low at the handle.
Self Heating
The measurement current of the instrument is just 0.3mA. Because of this comparably low current practically now self
heating effect has to be considered, even at air with low movement the self heating is <= 0.01°C.
Cooling by Evaporation
When measuring air temperature the probe has to be dry. Otherwise the cooling due to the evaporation causes too low
measurement.
Heat loss caused by probe construction:
Especially when measuring temperatures which deviate very much from the ambient temperature, measurement errors
often occur if the heat loss caused by the probe is not considered. When measuring fluids therefore the probe should be
emerged sufficiently deep and be stirred continuously. When measuring gases the probe should also emerge as deep
as possible in the gas to be measured (e.g. when measuring in channel/pipes) and the gas should flow around the
probe at sufficient flow.
Measuring Surface Temperature
If temperature of the surface of an object has to be measured, one should pay attention especially when measuring hot
(or very cold) surfaces, that the ambient air cools (or heats) the surface. Additionally the object will be cooled (or
heated) by the probe or the probe can have a better heat flow to the ambient temperature as to the objects surface.
Therefore specially designed surface probes should be used. The measurement precision depends mainly on he
construction of the probe and of the physics of the surface itself. If selecting a probe try to choose one with low mass
and heat flow from sensor to handle. Thermally conductive paste can increase the precision in some cases.
0
0,2
0,4
0,6
0,8
1
1,2
-50 -30 -10 10 30 50 70 90 110 130 150
Fehler [°C]
T [°C]
Fehler Gerät und Temperaturfühler
B
1/3
B

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7 Configuration of the Device
Follow these instructions to configure the functions of the device:
Switch device off.
Switch the device on and press during the segment test, until the display shows the first
parameter “P.OFF”
Set parameter with = up or = down.
Jump to the next parameter by pressing .
Parameter
Value
Information
Key
Keys
P.OFF
Auto Power-Off (turn-off delay) factory setting: 20 min.
1 …120
Auto Power-Off (turn-off delay) in minutes. If no key is pressed for the time
adjusted here, the device is automatically switched off (adjustable 1 … 120 min)
OFF
Auto power-off is deactivated (continuous operation)
UN,T
Display unit factory setting: °C
°C
Measuring value displayed in °Celsius
°F
Measuring value displayed in °Fahrenheit
AL
Alarm setting factory setting: oFF
OFF
no alarm monitoring
ON
alarm monitoring via display, interface and sound (Buzzer)
NO.SO
alarm monitoring via display, interface, no sound (Buzzer)
AL.LO
Alarm setting: Min factory setting: -5.0°C
-200.0 …
AL.K,
Min alarm limit, highest possible value: Max Alarm limit
AL.K,
Alarm setting: Max factory setting: -5.0°C
AL.LO …
400.0
Max alarm limit, lowest possible value: Min Alarm limit
ADR.
Base Address factory setting: 01
0 1 …9 1
Base address for serial interface communication
L,TE
Backlight -auto-off factory setting: 10 sec.
OFF
No backlight
5 …120
Backlight turns automatically off after 5 …120 s (battery saving)
ON
Backlight always on as long as device is switched on
AUTO
HLD
Auto Hold-Function factory setting:: oFF
ON
Auto Hold activated: automatic holding of the measured value, as soon as it is
stabilized.
OFF
Auto Hold deactivated: Value is frozen on keypress (hold)
INIT
Restore factory settings
NO
Parameters are not changed to factory settings.
YES
ATTENTION: All parameter are changed to factory settings.
Press again to store changed settings, the device restarts (segment test).
NOTE: If there is no key pressed within the menu mode within 2 minutes, the configuration will be
cancelled, the entered settings are lost!

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8 Adjustment
The instrument can be adjusted, assuming that: Reliable references are available, such as ice-
water regulated precision water baths or similar.
:
Displayed value °C =(measured value °C - OFFS) * (1 + slope correction / 100 )
Displayed value °F =(measured value °F - 32 °F - OFFS) * (1 + slope correction / 100 )
Follow these instructions to adjust the device:
Switch the device on.
Press and together until the first parameter “0FFS” is displayed.
Set parameter with = up or = down
Jump to the next parameter by pressing .
Parameter
Value
Information
Key
Keys
OFFSET correction factory setting: oFF = 0.0°C
OFF
No offset correction
-5.0 …5.0 °C
or
-9.0…9.0 °F
Value of offset correction
Slope correction factory setting: oFF= 0%
OFF
No slope correction
-5.00 …5.00
Value of slope correction in %
Press again to store changed settings, the device restarts (segment test).
NOTE: If there is no key pressed within the menu mode within 2 minutes, the configuration will
be cancelled, the entered settings are lost!
9 Error and System Messages
----
No temperature probe connected
Or at GMH 285 BNC: cable/sensor broken
Or at GMH 285: cable/sensor shorted
ERR. 1
Value exceeding measuring range, value too high or cable/sensor broken
ERR. 2
Value exceeding measuring range, value too low or cable/sensor shorted
ERR. 7
System error –the device has detected a system error (device defective or not within
working temperature)
The blinking bAt display indicates low battery voltage, device will continue to work for a
short time.
The battery is consumed and has to be changed. Measurements are no longer
possible.
10 Accuracy Inspection: Adjustment /Update Service
You can send the device to the manufacture or retailer for adjustment and inspection.
Moreover the manufacturer can do the latest software update. This ensures that future
improvements are provided to owners of older devices in a cost-saving way. You can display the
current software version if you do not release the on/off button after you switched the device on, but
hold it for more than 5 seconds. (i.e. “r. 1.0”)

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11 Disposal Notes
Dispense exhausted batteries at destined gathering places.
This device must not be disposed as ‘residual waste’
To dispose this device, please send it directly to us (adequately stamped).
We will dispose it appropriately and environmentally friendly.
12 Technical Data
Measurement
Resistive temperature measuring Pt1000
GMH 285-BNC: BNC socket
GMH 285: 3.5mm audio socket
Range
-200,0°C to 400,0°C / -200,0°F to 752,0°F
Resolution
0.1°C / 0.1°F
Accuracy
-100.0 … 200.0°C: +/-0.1°C +/-1 digits
else: +/-0,1 % of measured value +/-1 digits
Frequency
2 measurements per second
Display
4 ½ digits LCD (13 mm) with additional segments
Hold function
Press button to freeze current value.
or Auto hold: a stable value will automatically be captured with “HLD”
Min/Max memory
Highest and lowest values after switching on are memorized
Alarm
Freely configurable min/max alarm via buzzer, display and interface
Adjustment
Menue: offset/scale, factory settings are recoverable
Working temperature
-25 to 50°C
Storage temperature
-25 to 70°C
Power supply
9V battery, type: IEC 6F22 (included in scope of supply), external d.c. connector
Power consumption
< 0.20 mA (battery life time: more than 1500 hours for alkaline battery)
Backlight: <5mA, will be automatically switched of at “BAT”-warning
battery state display
“bAt” displayed in main display, if battery used up,
warning symbol: “BAT” for weak battery
Auto off-function
Device will be automatically switched off if not operated for longer time
(adjustable from 1..120 min)
Housing
impact-resistant ABS plastic housing
Protection class
Front side IP65
Dimensions
without BNC connector 142 x 71 x 26 mm (L x B x H) BNC connector at the
devices front end: approx. 13 mm long
Weight
Approx. 170 g incl. battery
EMC
The device corresponds to the essential protection ratings established in the
Regulations of the Council for the Approximation of Legislation for the member
countries regarding electromagnetic compatibility (2004/108/EG), additional error:
< 1% FS