iseg NHR 20 20, Technical Documentation Manual

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4. Options
4.1 VCT – voltage correction by temperature
This option allows a temperature dependent correction of the output voltage. The temperatures are measured with a
distinct sensor for each channel. An user-adjustable VCT-coefficient allows to specify a linear relationship between the
measured temperature and the output voltage. As an option one sensor per module can be
orded .
4.1.1. Technical data
Sensor type EPCOS B57867S0502F140
Temperature range -40 … 80°C
Accuracy of temperature measurement ±0.5 K (0 … 60°C)
Resolution of temperature measurement 1 mK (0 … 60°C)
Temperature update rate 15 updates/min
Table 7: Technical data VCT sensor
4.1.2. Operation
The connector of the temperature sensor must be plugged in the slot of the corresponding channel on the VCT-connector
at the rear panel of the HV-module.
A programmable VCT-coefficient for each channel defines the rate and the direction of the voltage correction. The
temperatures, measured at the sensors can be read out from the module.
At the time a HV-channel is switched on or the output voltage is set by the user, the module registers the
temperature (T
ref
) of the corresponding sensor and the set voltage as reference values.
If the temperature (T) at the sensor changes, the output voltage is automatically adjusted according to the formula:
V = V
ref
+ a • (T − T
ref
) (a…VCT-coefficient)
Example: A channel is set to 60V. At the time it is switched on a temperature of 25°C is measured. The VCT-coefficient is
set to +1V/K. If the temperature now increases to 26°C the output voltage will increase to 61V. (For channels with a
negative output voltage the voltage changes from –60V to –61V).
A VCT-coefficient of -1V/K would decrease the voltage to 59V.
Notes:
•
During operation the values for V
set
are adjusted. If a channel is switched off the adjusted set value will be kept, not the
original value set by the user.
•
If the VCT-coefficient if modified during operation, V
ref
and T
ref
are reset to the present values to prevent a sudden
voltage change.
•
If the temperature sensor is dis- and reconnected during operation,
V
ref
and T
ref
are reset to the present values to
prevent a sudden voltage change.
•
The temperature dependent voltage correction can be deactivated by setting the VCT-coefficient to 0 or by
disconnecting the temperature sensor. If this is done during operation, the channel will keep the actual voltage set.
•
If the temperature sensor is disconnected a temperature of -273.15°C is shown for that channel.
•
The VCT data points are described in the reference manual CAN EDCP Programmers-Guide (see appendix ) and in the
manual iseg Hardware Abstraction Layer (see appendix ) .
NHR – NIM standard High Voltage Power Supply | Last changed on: 25.11.2019 |
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