iseg VHQ 202M, VHQ 203M, VHQ 204L, VHQ 205L Operator's Manual

Spezialelektronik GmbH

iseg Spezialelektronik GmbH Email: [e-mail] Phone ++ 49 351 / 26 996 - 0
Bautzner Landstr. 23 http://www.iseg-hv.com Fax ++ 49 351 / 26 996 - 21
D - 01454 Radeberg / Rossendorf Germany

Precision High Voltage Supply VME STANDARD series

Operators Manual

Contents:

1. General information

2. Technical Data

3. VHQ Description

4. Front panel

5. Handling

6. VME Interface

7. Program example

Appendix A: Block diagram

Appendix B: Rotary switch locations

Attention!

-It is not allowed to use the unit if the covers have been
removed.

-We decline all responsibility for damages and injuries
caused by an improper use of the module. It is highly
recommended to read the operators manual before any
kind of operation.

Note

The information in this manual is subject to change without notice. We take no responsibility whatsoever for any
error in the document. We reserve the right to make changes in the product design without reservation and
without notification to the users.

Filename VHQx0x.___; version 3.00 as of 24.09.2004

Spezialelektronik GmbH

iseg Spezialelektronik GmbH Email: [e-mail] Phone ++ 49 351 / 26 996 - 0
Bautzner Landstr. 23 http://www.iseg-hv.com Fax ++ 49 351 / 26 996 - 21
D - 01454 Radeberg / Rossendorf Germany 2

1. General information

The VHQ´s are two channel high voltage supplies in 6U VME format, 164 mm deep, double width. The units
offers manual control and operation via VME bus. The use of the VME interface supports more then the manual
control functionality.
The high voltage supplies special provide high precision output voltage together with very low ripple and noise,
even under full load. Separate 10%-steps hardware switches put voltage and current limits. An INHIBIT input
protects connected sensitive devices. Additionally, the maximal output current per channel is programmable via
the interface. The high voltage outputs protected against overload and short circuit. The output polarity can be
switched over. The HV-GND is connected to the chassis and the powering GND.

2. Technical data:

VHQ two channel 202 M 203 M 204 L 205 L

Output voltage V

O

0 ... 2 kV 0 ... 3 kV 0 ... 4 kV 0 ... 5 kV

Output current per channel I

O

0 ... 3 mA 0 ... 2 mA 0 ... 1 mA 0 ... 1 mA

with option M - h

0 ... 6 mA 0 ... 4 mA 0 ... 3 mA 0 ... 2 mA

with option _104

100 µA 100 µA 100 µA 100 µA

Ripple typ. < 0,5 mV

P-P

< 0,5 mV

P-P

< 1 mV

P-P

< 2 mV

P-P

max. 2 mV

P-P

2 mV

P-P

2 mV

P-P

5 mV

P-P

Stability

∆V

O

<5 ∗ 10

-5

(idle to max. load)

∆V

O

/∆V

INPUT

<5 ∗ 10

-5

Temperature coefficient

<5 ∗ 10

-5

/K
LCD Display 4 digits with sign, switch controlled
voltage display in [V] / current display in [µA]
Resolution of measurement

Current: 1 µA, with option _104: 100 nA
Voltage: 1 V

Accuracy current measurement

±(0,05% I

O

+ 0,02% I

O max

+ 1 digit) (for one year)

Accuracy voltage measurement

±(0,05% V

O

+ 0,02% V

O max

+ 1 digit) (for one year)
Voltage CONTROL switch in upper position: 10 - turn potentiometer
control lower position (DAC): control via interface
Rate of change of hardware ramp 500 V/s (on HV-ON/ -OFF)
output voltage software ramp: 2 . . . 255 V/s
Protection - separate current and voltage limit

(hardware, rotary switch in 10%-steps)

- INHIBIT (ext. signal TTL-level,

Low = active ⇒ V

OUT

=0)

- programmable current limit (software)

Current trip reaction time < 60 ms

Power requirements V

INPUT

± 12 V ( < 850 mA, with option M - h < 1,6 A)
+ 5 V ( < 300 mA)
Packing VME #2 / 6U / 164 mm deep
Connector 96-pin VME connector according to DIN 41612
HV connector SHV-Connector at the front panel
INHIBIT connector 1-pin Lemo-hub
Operating temperature 0 ... +50 °C
Storage temperature -20 ... +60 °C

VHQ 205L

2 x 5 kV / 1 mA

Spezialelektronik GmbH

iseg Spezialelektronik GmbH Email: [e-mail] Phone ++ 49 351 / 26 996 - 0
Bautzner Landstr. 23 http://www.iseg-hv.com Fax ++ 49 351 / 26 996 - 21
D - 01454 Radeberg / Rossendorf Germany 3

3. VHQ Description

The function is described at a block diagram of the VHQ. This can be found in Appendix A.

High voltage supply

A patented high efficiency resonance converter circuit, which provides a low harmonic sine voltage on the HV­transformer, is used to generate the high voltage. The high voltage is rectified using a high speed HV-rectifier,
and the polarity is selected via a high-voltage switch. A consecutive active HV-filter damps the residual ripple
and ensures low ripple and noise values as well as the stability of the output voltage. A precision voltage divider
is integrated into the HV-filter to provide the set value of the output voltage, an additional voltage divider
supplies the measuring signal for the maximum voltage control. A precision measuring and AGC amplifier
compares the actual output voltage with the set value given by the DAC (computer control) or the potentiometer
(manual control). Signals for the control of the resonance converter and the stabilizer circuit are derived from
the result of the comparison. The two-stage layout of the control circuit results in an output voltage, stabilized
with very high precision to the set point.
Separate security circuits prevent exceeding the front-panel switch settings for the current I

max

and voltage V

max

limits. A monitoring circuit prevents malfunction caused by low supply voltage.
The internal error detection logic evaluates the corresponding error signals and the external INHIBIT signal. It
allows the detection of short overcurrent due to single flashovers in addition.

Digital control unit

A micro controller handles the internal control, evaluation and calibration functions of both channels. The actual
voltages and currents are read cyclically by an ADC with connected multiplexer and processed for display on
the 4 digit LCD display. The current and voltage hardware limits are retrieved cyclically several times per
second. The reference voltage source provides a precise voltage reference for the ADC and generation of the
control signals in the manual operation mode of the unit.
The set values for the corresponding channels are generated by a 16-Bit DAC in computer controlled mode.

Filter

A special property of the unit is a tuned filtering concept, which prevents radiation of electromagnetic
interference into the unit, as well as the emittance of interference by the module. A filtering network is located
next to the connectors for the supply voltage and the converter circuits of the individual devices are also
protected by filters. The high-voltage filters are housed in individual metal enclosures to shield even minimum
interference radiation.

Spezialelektronik GmbH

iseg Spezialelektronik GmbH Email: [e-mail] Phone ++ 49 351 / 26 996 - 0
Bautzner Landstr. 23 http://www.iseg-hv.com Fax ++ 49 351 / 26 996 - 21
D - 01454 Radeberg / Rossendorf Germany 4

4. Front panel

[1] 4 digit LCD display
[2] Channel switch
[3] Measuring switch
[4] Rotary switch Voltage limit
[5] Rotary switch Current limit
[6] Error indicator
[7] 10 - turn potentiometer
[8] HV-ON switch
[9] CONTROL switch
[10] KILL switch
[11] INHIBIT input
[12] HV-ON indicator
[13] HV-output
[14] Polarity indicator

5. Handling

The state of readiness of the unit is produced at the VME connector on the flipside.
The Output polarity is selectable with help of a rotary switch on the cover side (see appendix B). The chosen

polarity is displayed by a LED on the front panel [14] and a sign on the LCD display [1].

Attention!

It is not allowed to change the polarity under power!
An undefined switch setting (not at one of the end positions) will cause no output voltage.
High voltage output is switched on with HV-ON switch [8] at the front panel. The viability is signaled by the

yellow LED [12].

Attention!

If the CONTROL switch [9] is in upper position (manual control), high voltage is generated

at HV-output [13] on the front panel with a ramp speed from 500 V/s (hardware ramp) to

the set voltage chosen via 10-turn potentiometer [7].

This is also the case, if VME control is switched over to manual control while operating.
If the CONTROL switch [9] is in lower position (DAC), high voltage will be activated only after receiving

corresponding VME commands.