Arbiter Systems 1088A, Operation Manual

Page: 183 / 279

C.15 Option 19: Model 1088B Fault Relay 163
Special Note
In some applications, the fault relay may be required to switch into a capacitive load. An example
would be an input to a substation DFR or SER, in which a capacitor is placed across the input
terminals for surge or noise suppression (see schematic below).
Figure C.19: Option 19 Relay Circuit without Resistor
Note that if the relay contacts are closed, a substantial momentary current will flow into the 0.1 uf
capacitor. This could damage or degrade the contacts of the relay. This problem may be alleviated
by adding a 100 ohm, 0.5 watt resistor in series with the relay, thereby limiting the charging current
to the capacitor (see below).
Figure C.20: Option 19 Relay Circuit with Resistor
This resistor is not normally installed at the factory, due to the range of different applications in
which Option 19 may be used, and the fact that in many applications, no resistor is needed or
desired.
The modification can be implemented by adding a resistor to the Option 19 circuit board inside of
the Model 1088B. The following steps describe the procedure necessary for installing the resistor.