22
4.2.2.6. Dry Contacts (Optional Hardware)
Free contact relay connection cables shall have a cross-section of 1.5 mm
2
.
Maximum allowed resistive contact currents for several voltages are given on the table below:
Maximum contact current for resistive load
Each relay has both a normally open (NO) and a normally closed (NC) contact. One end of these
contacts is common. Normal states of the relay contacts are shown on the figure at the beginning
of the “communications” section.
Relay functions are described below:
Contacts change position if the rms value or frequency of the
mains voltage is beyond their limits.
Contacts change position if the UPS is working in the bypass
mode
BUVR (Battery under voltage relay)
Contacts change position if the battery voltages are critically
low to feed the load and the load power is about to be
interrupted
SBFR (secure bus failure relay)
Contacts change position, if the output voltage disappears
Maximum voltage to be applied to the relay contacts is 42V AC rms (sinus) or 60 Vdc.
Maximum contact current depends on the applied voltage and the load characteristic. Both
maximum voltage and maximum contact current corresponding to the applied voltage shall
not be exceeded.