Danfoss AK-CH 650 User Manual

92 Capacity controller RS8ER302 © Danfoss 2016-02 AK-CH 650
Pump control
The controller can control and monitor one or two pumps that
circulate the brine.
If two pumps are used, and operating time equalisation is se-
lected, the controller can also perform a changeover between the
two pumps if operating alarms occur.
Activity in the case of operating alarm
Pump selection is performed using the following setting:
0: Both pumps are stopped
1: Pump 1 is started up
2: Pump 2 is started up
3: Both pumps are started up
4: Automatic changeover between the pumps is permitted. Start
before stop.
5: Automatic changeover between the pumps is permitted. Stop
before start.
(This function is used when both pumps are controlled in shifts by
the same frequency converter.)
Automatic changeover between the pumps (only for setting = 4
and 5)
Using this setting there can be alternation between the two
pumps so that a type of operating time equalisation is achieved.
The period between the pump changeovers can be set as "Pump-
Cycle". On changeover to the second pump, the rst one will
remain in operation for the "PumpDel" time. It will then stop.
At stop before start "PumpDel" will be the break time for changeo-
ver.
Pump monitoring
The controller monitors pump operation via one or two safety
input.
At one signal the setting "Common" is selected, and the signal
can originate from a pressure dierence pressure switch or a ow
switch.
At two signals the setting "Individual" is selected. The two signals
must then be received at two digital inputs. The signals may be
retrieved from the two motor protectors.
Here too, set an alarm delay time that applies during startup and
on pump changeover.
The delay time is to ensure that on startup/pump changeover, no
error is signalled for a pump before brine ow has been estab-
lished.
The special case of operating time equalisation
If the pumps are running with automatic operating time equalisa-
tion, the controller can perform a changeover of the pumps in a
case where there is no ow.
Depending on whether pump changeover neutralises the alarm
situation or not, the following occurs:
1) Pump changeover neutralises the alarm situation before the
alarm delay expires.
If pump changeover neutralises the alarm situation, the non-
faulty pump, now in operation, will run until the normal cycle
time has expired. After that, there is changeover again to the
"faulty pump", as it is assumed to have been repaired. At the
same time, the alarm situation is reset (the alarm is acknowl-
edged).
If the faulty pump has not been repaired, this will still trigger
an alarm and still result in changeover to the pump that is not
faulty. This is repeated until conditions are returned to normal.
2) Pump changeover does not neutralise the alarm situation
before the alarm delay expires.
If the alarm, on the other hand, is active after pump changeover,
the controller will also emit an alarm for the second pump. At
the same time, both pump outputs are activated in an attempt
to create enough ow for the alarm situation to be neutralised.
From now on, the controller will have both pump outputs
activated until the normal cycle time has expired, after which
the alarm situation is reset and pump changeover to one pump
is performed again.
Separate alarm priorities can be set for drop out of one pump and
for drop out of both pumps. See the Alarms and Messages section.
Alarm handling
Pump alarms are suppressed/acknowledged when normal pump
changeover is performed after the cycle time has expired.
Pump alarms can also be suppressed by setting pump selection
to the "faulty" pump - if the ow switch is OK, the alarm will be
acknowledged/suppressed as a result.
Start before stop
Stop before start

Danfoss AK-CH 650 Specifications

General

Brand	Danfoss
Model	AK-CH 650
Category	Controller
Language	English