Twickenham Scientific Instruments Ltd.

The Helium Depth Indicator - Specifications and options

Physical

Size: 144w x 72h x 200d.

Weight: 1.5 kg.

Case is bench or panel mounting.

Front panel

Display: 8 Character large (9 mm) backlit Liquid Crystal Display.

Switches: 3 momentary make switches to control functions.

Back panel

Power input:
Mains: 95 - 250V ac via switched fused IEC mains input.

Auxiliary: 24V dc via power jack socket.

Probe input: One 7 pin connector.

Analogue output & External Inhibit: In shared 6 way Weidmuller connector.

Analogue output is either

4-20mA (A),
Analogue voltage - settable for mV/mm output (V),
Analogue voltage 0 - 10V output (T)

and one of these are supplied on all HDI units. All options are short circuit protected.

External Inhibit. Opto-isolated input, triggered by 5 - 20V or 3 - 15mA at terminals.

Serial port
Connector: Standard DB9-F connector.

Functional Parameters

Resolution: 1mm.

Linearity: 1 LSD (Least Significant Digit).

Accuracy: 0.5% +/- 1 LSD.

Compliance voltage: 55 +/- 5V.

Maximum active length per channel: 2000mm.

Options

Control and alarm (C) option

Two independent control signals are provided by no-volt relay contacts, rated at 24V 0.5A ac or dc. Alarm signal provided by an open collector output, 50mA maximum. Set points and channel assignment via the front panel controls.

Connector: DB9-M connector on the back panel.

Two probe input (2) option

Provides a second standard 7 pin probe input socket on the back panel, and a second probe cable. Allows two helium and/or nitrogen probes to be connected at the same time.

Fischer connector probe input (F) option

Provides the facility to connect one or two probes via one or two Fischer connector(s) instead of one (or two) standard 7 pin connector(s). This option is particularly suited for wire ended helium probes installed within a cryostat, and where the customer provides the external wiring, or for probes with the 7F connector option. The mating connector is supplied, probe cables can be supplied as an extra accessory..

Connector: 103 series, 7 pin Fischer.

Lemo connector probe input (L) option

Provides the facility to connect one or two probes via one Lemo connector instead of one (or two) standard 7 pin connector(s). This option is particularly suited for wire ended helium probes installed within a cryostat, and where the customer provides the external wiring. The mating connector is supplied, but no probe cables.

Connector: 1B series, 8 pin Lemo.

Second analogue output (Z) option

For units with either the 2 or L options, the Z option provides a second analogue output corresponding to the reading from the second probe. When this option is selected, the External Inhibit is not available, as the second output is fed from the second pair of pins in the shared MOLEX connector. Both analogue outputs are of the same type, that is A, V or T.

Supply Options

These options specify the removal of an item normally supplied, and the substitution, where appropriate of an alternative.

Connector only options

In some cases, the system already has all the wiring extant, and that only the suitable connector is required for installation to the HDI, rather than the standard 4m probe cable. (Likewise with the Lemo and Fischer connector probe input option). These are:

P The standard probe cable is replaced by the 7 pin male connector and hood.
N Neither probe cable or 7 pin connector are supplied for the probe input connector.

If the 2 option is also required for the system:

2P One probe cable and one 7 pin male connector and hood.

2P2 Two 7 pin male connectors and hoods; no probe cables.