10
BG 5043 BEN / A (2016-10) PTR225_237.oi
DANGER
The Penning gauge PTR 225, PTR 225 S or PTR 237 may only be
connected to supply units or measuring instruments which meet the
requirements of mains isolated extra-low voltages (PELV) and
VDE 0100.
The Penning gauges PTR 225, PTR 225 S or PTR 237 is capable of operating off
supply voltages ranging from 14.5 V to 36 V. A supply voltage of 24 V DC is recom-
mended.
The power supply must be connected to Pin 1 (+) and Pin 2 (power supply ground).
The high voltage may be switched on either through Pin 7 using negative logic or
Pin 8 using positive logic.
In each case Pin 2 must be used as the reference potential.
Pin 7 switches the high voltage on when
•
contact is established with Pin 2 or
•
a voltage of less than 2.5 V is present with reference to Pin 2.
Pin 7 switches the high voltage off when
•
there is no contact with Pin 2 (open input) or
•
a voltage greater than 4 V is present with reference to Pin 2.
Pin 8 switches the high voltage on when
•
contact is established with Pin 1 (supply voltage) or
•
a voltage greater than 12 V is present with reference to Pin 2.
Pin 8 switches the high voltage off when
•
there is no contact with Pin 1 (open input) or
•
a voltage of less than 7 V is present with reference to Pin 2.
Operation of the PTR 225, PTR 225 S or PTR 237 in the pressure range above
10
-2
mbar will cause the accumulation of contaminations and will thus reduce
service life. For this reason, the high tension should only be switched on or off
when the pressure has dropped to the 10-2 to 10-3 mbar range.
The high tension may also be switched on or off directly by the output signal pro-
vided by a Pirani gauge TTR 91 S / TTR 96 S. Thus the Penning gauge can be
switched on or off automatically at a pressure of approximately 5·10
-3
mbar.
The PTR 225, PTR 225 S or PTR 237 supplies a defined output signal ranging
from 0.66 V to 10 V at Pin 3 with reference to Pin 5 which is signal ground. For this
also refer to Table 1 in Annex A.
Table 1 has been included to clarify the relationship between the output voltage
and the pressure.
The measurement signal provided by the Penning gauge depends on the type of
gas. The values stated in Table 1 apply to nitrogen and air. For other gases,
corresponding correction factors must be used which are available from Pfeiffer
Vacuum upon request.
3.2.1 Power Supply
3.2.2 Switching on the High
Tension
3.2.3 Measurement Signal
Output
