Alpha III Series Data Sheet

Description
The Alpha III series of precision laboratory high voltage supplies includes three models to cover the range of voltages up to 30 kV at power levels up to 45 Watts. Operating from standard mains power, these units provide a well stabilised, low ripple output with good static and dynamic load regulation. The high voltage sections are fully encapsulated, and the reversible plug-in voltage multiplier enables a single unit to generate positive or negative output polarity as required, the polarity selected being indicated by a front panel lamp. Front panel controls and voltage and current meters are fitted, with a switch to select local or remote control, but an option is to have a plain front panel with remote control only. A further option is that of computer control via an RS232 serial link; with this option, software is supplied on disk to operate under MS-DOS. The units incorporate comprehensive protection, with switch selectable LIMIT or TRIP function, the limit or trip levels being set by front panel controls or remotely. A Brandenburg type 37 moulded output socket is fitted, and a 2 m long output cable is supplied, fitted with a mating connector. The power supplies may be used on the bench or rack mounted (height 3U).

Description

The Alpha III series of precision laboratory high voltage supplies includes three models to cover the range of voltages up to 30 kV at power levels up to 45 Watts. Operating from standard mains power, these units provide a well stabilised, low ripple output with good static and dynamic load regulation. The high voltage sections are fully encapsulated, and the reversible plug-in voltage multiplier enables a single unit to generate positive or negative output polarity as required, the polarity selected being indicated by a front panel lamp. Front panel controls and voltage and current meters are fitted, with a switch to select local or remote control, but an option is to have a plain front panel with remote control only. A further option is that of computer control via an RS232 serial link; with this option, software is supplied on disk to operate under MS-DOS.
The units incorporate comprehensive protection, with switch selectable LIMIT or TRIP function, the limit or trip levels being set by front panel controls or remotely. A Brandenburg type 37 moulded output socket is fitted, and a 2 m long output cable is supplied, fitted with a mating connector. The power supplies may be used on the bench or rack mounted (height 3U).

Output Voltage Range	Output Current	Output Ripple	Front Panel Switches/Meters	RS232 Interface	Order Code
20V to 5kV	0 to 10mA	1.5V	Yes	No	3507
20V to 5kV	0 to 10mA	1.5V	Yes	Yes	3507-01
25V to 15kV	0 to 3.0mA	1.5V	Yes	No	3707
25V to 15kV	0 to 3.0mA	1.5V	Yes	Yes	3707-01
30V to 30kV	0 to 1.5mA	3.0V	Yes	No	3807
30V to 30kV	0 to 1.5mA	3.0V	Yes	Yes	3807-01
All versions have rear panel selector to select nominal input voltage: 100V, 120V, 220V or 240V at 50/60Hz

Output Voltage Range

Output Current

Output Ripple

Front Panel Switches/Meters

RS232 Interface

Order Code

20V to 5kV

0 to 10mA

1.5V

Yes

3507

20V to 5kV

0 to 10mA

1.5V

Yes

3507-01

25V to 15kV

0 to 3.0mA

1.5V

Yes

3707

25V to 15kV

0 to 3.0mA

1.5V

Yes

3707-01

30V to 30kV

0 to 1.5mA

3.0V

Yes

3807

30V to 30kV

0 to 1.5mA

3.0V

Yes

3807-01

All versions have rear panel selector to select nominal input voltage: 100V, 120V, 220V or 240V at 50/60Hz

Electrical Specification
AC supply input	100V selected 90V to 110V ac, 48 to 62Hz 120V selected 110V to 130V ac, 48 to 62Hz 220V selected 210V to 230V ac, 48 to 62Hz 240V selected 230V to 250V ac, 48 to 62Hz
Input power at full load	70 VA approx. (80 VA if RS232 interface board fitted)
Output voltage range	see Ordering Information
Output polarity	Positive or negative, depending on the position of the HV multiplier module fitted to the rear panel.
Output current range	see Ordering Information
Control of output	(1) If LOCAL is selected, front panel controls are effective. These are: HV on/off switch, Trip/Limit switch, Voltage (coarse), Voltage (fine) and Current controls. See below for details of control operation. Local control is not available on -02 and -03 versions. (2) If REMOTE is selected, control inputs to rear panel REMOTE connector are effective. All control functions are the same as under LOCAL control. (3) Links may be made on the REMOTE connector to enable some functions to be controlled from the front panel and others remotely. For this mode, REMOTE must be selected. (4) On -01 and -03 versions, REMOTE control may be effected via the RS232 serial link.
Output ripple	see Ordering Information
Line regulation	10 ppm (max.) for ņ10% mains voltage change
Load regulation	(static) 20 ppm (max.) for zero to full load (dynamic) see typical trace
Output drift	20 ppm (max.) in any 15 min. period (after45 min. warm-up)
Temperature coefficient	50 ppm per deg.C (max.)
Protection	(1)Protected against overloads or short circuits by TRIP/LIMIT options (see below) (2) Protected against output overvoltage by pre-set voltage limit potentiometer on rear panel
Front Panel Meters	Not fitted to -02 and -03 versions
Analogue voltmeter	Reads from zero to the maximum output voltage (see Ordering Information)
Analogue current meter	Reads from zero to the maximum output current (see Ordering Information)
Operation of Front Panel Controls (with LOCAL selected)	Not fitted to -02 and -03 versions
Mains ON/OFF switch	When switched ON, indicator lamp is lit and control circuits are activated. HV output circuits are not activated until HV ON/OFF push button is pressed.
Polarity indicator lamps	When mains switch is ON, the + or - indicator lamp lights to show the output polarity, depending on the position in which the HV multiplier module is fitted to the rear panel.
HV ON/OFF push button	Pressing this switch toggles the HV output circuits ON and OFF. When ON, the HV indicator lamp is lit.
TRIP/LIMIT switch	To use the TRIP function, connections must be made to the appropriate pins of the rear panel REMOTE connector, in order to select either constant-voltage operation with a pre-set current trip level, or constant-current operation with a pre-set voltage trip level. In either mode, if the unit trips out it may be reset by pressing the HV ON/OFF button twice. When LIMIT is selected, the power supply operates either in constant-voltage or constant-current mode, depending on the load impedance, with automatic crossover from one mode to the other. The level of voltage or current is as set by the appropriate controls (local or remote). In constant-voltage mode, an over-riding voltage limit is set by a potentiometer on the rear panel.
Voltage controls	VOLTAGE COARSE and FINE potentiometers set the output voltage in constant-voltage mode
Current control	CURRENT potentiometer sets the output current in constant-current mode
Remote Control Operation (REMOTE selected)	All remote connections are made to the REMOTE connector on the rear panel (15 way "D" type, male pins).
HV ON/OFF	TTL and CMOS compatible. HV is OFF if this input is HIGH (> +1.5V) or open circuit. HV is ON if this input is LOW (< +1.0V)
Voltage control input	Analogue input voltage 0 to +10V dc controls output voltage from zero to maximum when in constant-voltage mode, or sets voltage limit when in constant-current mode
Current control input	Analogue input voltage 0 to +10V dc controls output current from zero to maximum when in constant-current mode, or sets current limit when in constant-voltage mode
Voltage/Current Trip	Selector pins to be hard wired or connected to an external switch
Voltage monitor output	Output voltage 0 to +10V dc represents zero to maximum voltage. Accuracy +/-1%
Current monitor output	Output voltage 0 to +10V dc represents zero to maximum current. Accuracy +/-1%
Buffered ref output	+10.0V dc +/-1%, capable of sourcing up to 10mA
Front panel control voltages	The voltages from the front panel Voltage and Current control potentiometers are brought out to connector pins. By linking these to the control input pins, one or more of the front panel controls may be used when in REMOTE mode.
Computer Remote Control via RS232C Serial Link (-01 and -03 versions)	All remote functions may be actuated from a computer operating under MS-DOS, using the serial link and software supplied with the unit. All digital interface connections are opto-isolated.
Interface specification	Conforms to RS232C
Data rate	Selectable over the range 75 to 19200 bits/sec
Word length	Selectable: 7 or 8 bits
Parity checking	Selectable: odd, even or none

Electrical Specification

AC supply input

100V selected 90V to 110V ac, 48 to 62Hz
120V selected 110V to 130V ac, 48 to 62Hz
220V selected 210V to 230V ac, 48 to 62Hz
240V selected 230V to 250V ac, 48 to 62Hz

Input power at full load

70 VA approx. (80 VA if RS232 interface board fitted)

Output voltage range

see Ordering Information

Output polarity

Positive or negative, depending on the position of the HV multiplier module fitted to the rear panel.

Output current range

see Ordering Information

Control of output

(1) If LOCAL is selected, front panel controls are effective. These are: HV on/off switch, Trip/Limit switch, Voltage (coarse), Voltage (fine) and Current controls. See below for details of control operation. Local control is not available on -02 and -03 versions.
(2) If REMOTE is selected, control inputs to rear panel REMOTE connector are effective. All control functions are the same as under LOCAL control.
(3) Links may be made on the REMOTE connector to enable some functions to be controlled from the front panel and others remotely. For this mode, REMOTE must be selected.
(4) On -01 and -03 versions, REMOTE control may be effected via the RS232 serial link.

Output ripple

see Ordering Information

Line regulation

10 ppm (max.) for ņ10% mains voltage change

Load regulation

(static) 20 ppm (max.) for zero to full load
(dynamic) see typical trace

Output drift

20 ppm (max.) in any 15 min. period (after45 min. warm-up)

Temperature coefficient

50 ppm per deg.C (max.)

Protection

(1)Protected against overloads or short circuits by TRIP/LIMIT options (see below)
(2) Protected against output overvoltage by pre-set voltage limit potentiometer on rear panel

Front Panel Meters

Not fitted to -02 and -03 versions

Analogue voltmeter

Reads from zero to the maximum output voltage (see Ordering Information)

Analogue current meter

Reads from zero to the maximum output current (see Ordering Information)

Operation of Front Panel Controls (with LOCAL selected)

Not fitted to -02 and -03 versions

Mains ON/OFF switch

When switched ON, indicator lamp is lit and control circuits are activated. HV output circuits are not activated until HV ON/OFF push button is pressed.

Polarity indicator lamps

When mains switch is ON, the + or - indicator lamp lights to show the output polarity, depending on the position in which the HV multiplier module is fitted to the rear panel.

HV ON/OFF push button

Pressing this switch toggles the HV output circuits ON and OFF. When ON, the HV indicator lamp is lit.

TRIP/LIMIT switch

To use the TRIP function, connections must be made to the appropriate pins of the rear panel REMOTE connector, in order to select either constant-voltage operation with a pre-set current trip level, or constant-current operation with a pre-set voltage trip level. In either mode, if the unit trips out it may be reset by pressing the HV ON/OFF button twice.

When LIMIT is selected, the power supply operates either in constant-voltage or constant-current mode, depending on the load impedance, with automatic crossover from one mode to the other. The level of voltage or current is as set by the appropriate controls (local or remote). In constant-voltage mode, an over-riding voltage limit is set by a potentiometer on the rear panel.

Voltage controls

VOLTAGE COARSE and FINE potentiometers set the output voltage in constant-voltage mode

Current control

CURRENT potentiometer sets the output current in constant-current mode

Remote Control Operation (REMOTE selected)

All remote connections are made to the REMOTE connector on the rear panel (15 way "D" type, male pins).

HV ON/OFF

TTL and CMOS compatible. HV is OFF if this input is HIGH (> +1.5V) or open circuit. HV is ON if this input is LOW (< +1.0V)

Voltage control input

Analogue input voltage 0 to +10V dc controls output voltage from zero to maximum when in constant-voltage mode, or sets voltage limit when in constant-current mode

Current control input

Analogue input voltage 0 to +10V dc controls output current from zero to maximum when in constant-current mode, or sets current limit when in constant-voltage mode

Voltage/Current Trip

Selector pins to be hard wired or connected to an external switch

Voltage monitor output

Output voltage 0 to +10V dc represents zero to maximum voltage. Accuracy +/-1%

Current monitor output

Output voltage 0 to +10V dc represents zero to maximum current. Accuracy +/-1%

Buffered ref output

+10.0V dc +/-1%, capable of sourcing up to 10mA

Front panel control voltages

The voltages from the front panel Voltage and Current control potentiometers are brought out to connector pins. By linking these to the control input pins, one or more of the front panel controls may be used when in REMOTE mode.

Computer Remote Control via RS232C Serial Link (-01 and -03 versions)

All remote functions may be actuated from a computer operating under MS-DOS, using the serial link and software supplied with the unit. All digital interface connections are opto-isolated.

Interface specification

Conforms to RS232C

Data rate

Selectable over the range 75 to 19200 bits/sec

Word length

Selectable: 7 or 8 bits

Parity checking

Selectable: odd, even or none

Environmental Specification
Operating temperature range	0 to +50 deg.C
Storage temperature range	-20 to +70 deg.C
All high voltage assemblies are fully encapsulated for protection against high humidity

Electrical Specification
Dimensions	482mm (w) x 133mm (h) x 305mm (d)
Weight	10kg approx.
Connections	Mains: CEE22 male connector with built-in voltage selector, fuses and RFI suppressor. A 2m long 3-core mains lead with moulded-on CEE22 female connector is supplied. Earth: Screw terminal, internally linked to chassis HV output: Brandenburg Type 37 moulded socket. A 2m long output cable with mating connector is supplied. HV return: Screw terminal, internally linked to chassis Remote: 15 way "D" type (male pin) RS232: 9 way "D type (male pin) For pin connections, see User Manual