VTA
H172203_1_001 189 / 234
CryoProbe Adaptation (VTA CRP)
In contrast to the room temperature probes the CryoProbes use PT100 sensors for both
regulator and safety temperature measurement. Their heater impedance is higher than that of
a room temperature probe.
Furthermore, the analog signal from the safety sensor must be wired to the CryoPlatform
which also delivers the bias current. This ‘lending-out’ of the safety sensor establishes a
redundant system for sample temperature monitoring. To prevent ground coupling, the
signals between the BSMS and the CryoPlatform are galvanically isolated. If the
CryoPlatform is switched off, the VTA is unable to measure the safety sensor and thus
inhibits sample heating.
Care must be taken when connecting the CryoPlatform: The male connector on the
CryoPlatform side exposes a voltage of about 29 V on a pin. It is almost impossible to plug
the VTA cable without shorting this pin to frame ground which can damage the CRCO and
the VTA. Always switch off the CryoPlatform when connecting the VTA CRP to its rear panel!
The VTA can be left connected to CryoPlatform and must not be disconnected when
operating a RT probe.
BCU-05 and BCU-X Adaptation (VTA BCU)
To integrate the legacy BCU gas chillers into the new temperature system an adaptor VTA is
needed. It detects the presence of such a chiller and enables remote operation.
The VTA BCU can be used for BCU05 or BCU-X (BCU-Extreme) type of cooling units and
can be connected to an auxiliary control port.
New BCU I and BCU II do not need a VTA BCU adapter. They come with an embedded VTA-
style interface and should be connected to an auxiliary control port.
Adaptation of Low Temperature Options (VTA LN2)
For sample temperature control far below room temperature two devices are available: the
LN2 Heat Exchanger and the LN2 Evaporator.
The VTA LN2 adapts both and detects the type of the connected device. It monitors the level
and safety sensors and continuously sends these values to the BSMS/2 ELCB where they
are evaluated.
For LN2 Heat Exchanger and LN2 Evaporator operation heater power is required. The heater
power is fed through the VTA and the heater safety sensor is monitored for safe operation.
For that an additional heater cable is necessary (Z116301 CABLE RD 15P 4.5M 1:1 BSMS/2
VPSB-VTA or Z116304 CABLE RD 15P 9M 1:1 BSMS/2 VPSB-VTA).
16.4.1 Protection
All external interfaces are protected against short circuits. The monitoring takes place on the
VPSB board (measurement electronics) and on the ELCB board (monitoring of low level
measurements from the VPSB board).
Monitored are:
• Heater and controller temperature
• Heater -voltage and -current
• Impedance of connected devices (e.g. heater)
• Communication between VTA and VPSB
Supervision is done via status information.
If one of the measurements is outside the tolerance, the BSVT and all connected devices will
switch off.
To Next Page
Loading...
General