5
Errors
‘Err’
message
This is only displayed when in run mode and there is a problem with
the relays. The most common cause is one or both of the relays ON and
OFF points are the same.
dp
not blinking
If the decimal point is not blinking the unit may have been
unintentionally left in program mode. Press the
‘M’
key repeat until
‘Fin’
is displayed the press the
‘E’
key, this will exit programme mode
Alternatively momentarily turn the power
OFF
and then back
ON.
Power Backup System
Uninterrupted systems can be implemented using a backup battery, If a backup system is
required it would be normal to specify a DC model. The normal configuration is to use
18VDC to 24VDC derived from an AC power supply and a 12VDC external battery. When
mains AC is present the Type 900 operates from the DC output from the mains AC power
supply, when the mains AC fails the Type 900 operates from the battery. It is essential to
put a diode such as a IN4001 in series with each of the +V supplies to the 900, see diagram
below. Optionally a solar panel could be used as well as a recharging system.
NOTE:
If power falls then it may be the case where the relay contacts lose their voltage
too. Backup systems are useful where supplies are from different sources or the Type 900
relays are used to drive other relays for control and indication.
