HP 6633B - Manual (Page 25)

Installation - 3
25
Under normal operation, the dc source senses the output voltage at the output terminals on the back
of the unit. External sense terminals are available on the back of the unit that allow the output
voltages to be sensed at the load, compensating for impedance losses in the load wiring. You
cannot remote sense at the optional front panel binding posts.
The output terminal block of the unit is shipped configured for local sensing, with the +S terminal
jumpered to +, and the
−
S terminal jumpered to
−
. Remove these jumpers when making your sense
wire connections. The terminal block screws are 6-32 X 3/8 inch.
Sense Leads
The sense leads are part of the dc source's feedback path and must be kept at a low resistance (less
than several ohms) to maintain optimal performance. Connect the sense leads carefully so that they
do not become open-circuited. If the sense leads are left unconnected or become open during
operation, the dc source will regulate at the output terminals, resulting in a 3% to 5% increase in
output over the programmed value. Shorting the sense leads trips the OVP circuit.
NOTE: It is good engineering practice to twist and shield all signal wires to and from the
sense connectors. Connect the shield at the dc source end only. Do not use the
shield as one of the sensing conductors.
+S + - -S
+ 240 VDC MAX TO
-
+
- twisted or
shielded pair
LOAD
remove
sense
jumpers
Figure 3-3. Remote Sense Connections
The overvoltage protection circuit senses voltage near the output terminals, not at the load.
Therefore the signal sensed by the OVP circuit can be significantly higher than the actual voltage