Remote Sensing | B&K 1794 guide

4.4Positive or negative voltage can be obtained from this supply by grounding either one of the output terminals or one end of the load. Always use two leads to connect load to the supply, regardless of where the setup is grounded. This will eliminate any possibility of the output current return paths through the power source ground which would damage the line cord plug. This supply can also be operated upto ±300V DC above ground, if neither output terminal is grounded.

4.5REMOTE SENSING :

Warning : Do not Operate the Unit in 'REMOTE SENSE' mode without ensuring proper 'REMOTE/ 4 TERMINAL' Connections. Serious Damage to Unit or Equipment under test could result.

Remote sensing is used to maintain good regulation at the load and reduce the degradation of regulation which could occur due to the voltage drop in the leads betweeen the power supply and the load. Remote sensing is accomplished by connnecting the load to remote sense terminals on the front panel. The leads from the sensing( +S and -S) terminals to the load will carry much less current than the load leads and it is not required that these leads be as heavy as the load leads. However, they must be twisted or shielded to minimize noise pickup.

For reasonable lengths of load leads, remote sensing greatly improves the performance of the supply. However, if the load is located at a considerable distance from the supply, added precautions must be observed to obtain satisfactory operation. Notice that the voltage in the load leads subtracts directly from the available output voltage and also reduces the amplitude of the feedback error signals that are developed within the unit. Because of these factors, it is recommended that the drop in each load lead does not exceed 0.5Volts.

NOTE : Due to the voltage drop in load leads, it may be necessary to

readjust the current limit in the remote sensing mode.

Observance of the precautions in para. 4.8 and 4.9 will result in a low dc output impedance at the load. However, another factor that must be considered is the inductance of long leads.This causes a high ac impedance and could affect the stability of the feed back loop seriously enough to cause oscillations. If this is the case, it is recommended that the following actions be taken:

a)Adjust R6 to remove oscillations, or to achieve best possible transient response for given long load lead configuration.

b)If performing adjustment in step (a) above does not remove oscillation, disconn-ect output capacitor C3 ( L1791-FP-CNT-0603 PCB ) and connect a capacitor having similar characteristics (approximately the same capaci tance, the same voltage rating or greater, and having good high frequency characteristics) directly across load using short leads.

Readjust R6 as in step (a) above after making this change.