WATTrouter M - user manual
How to fit and setup the device
Page 37 from 79
the part of surplus energy will be still delivered to public grid as in the case of the default function of
WATTrouter controller, without prepend mode.
Example 2:
A boiler and 2 other heating elements:
- the boiler connected to SSR No. 1, 1st priority, connected power 2 kW, maximum power 2 kW,
- 1st heating coil connected to SSR No. 2, 2nd priority, connected power 2 kW, maximum power 2 kW,
- 2nd heating coil connected to relay No. 1, 3rd priority, connected power 2 kW,
a)
Prepend value set to
0
: In this case the 2nd coil will never be prepended and after 4kW
surplus is reached and consumed by boiler and 1st coil the controller will wait until the
available surplus is 6kW. Then it connects 2nd coil. In the meantime surplus flows to public
grid.
b)
Prepend value set to
1
: In order to prioritize the 2nd coil, we will take into account only the
load power of the 1st coil, which means that the boiler will always have first priority. So after
PV-surplus reaches 4 kW the 2nd coil will be connected (prepended) before the 1st coil.
c)
Prepend value set to
2 and higher
: In order to prioritize the 2nd coil, we will take into
account the sum of load powers of the boiler and 1st coil. So after surplus reaches 2 kW the
2nd coil will be connected (prepended) before boiler and 1st coil.
Note:
The Prepend function does not affect relay output priorities. For example, if the relay 2 is set to
the nearest lower priority than the relay 1 but has a higher Prepend value than the relay 1, the relay 2
will not be prepended before the relay 1. Therefore, in this case, higher Prepend value for relay 2 than
for relay 1 is not meaningful, so don’t set it.
Minimum power – for proportional outputs when PWM function is used this value gives the minimum
power for the connected load. The output will not be activated unless available surplus energy
exceeds this threshold. Nonzero value can be useful e.g. for proportional control of inverter air
conditioner or heating pump. These devices usually don’t run with less than 1/3 of nominal power. For
more information about controlling air conditioners or heating pumps proportionally see
manufacturer’s web site.
PWM-I – for proportional outputs when PWM function is used then this value is equal to the I-
component value of the PID-regulator assigned to this output. The value can be selected between 1
and 1000. Select value according to the dynamics of the connected system (battery charger, heating
pump etc.). Start with a small value (1 to 10) and gradually increase the value if the system dynamics is
slow. For values less than 100 the dynamics is rather slow so that the system allows switching outputs
with lower priorities, to cover available surplus energy. If the Minimum power field is nonzero the
control will start after 3 minutes. In the meantime minimum power is held – aimed for softstart of air
conditioners or heating pumps.
Caution: In case of a too big PWM-I value the system may become unstable and this status may
damage the connected device, when there is no built-in protection in the device!
PWM range – (since firmware version 3.0) these values can be used to limit physical PWM or 0-10V
output to given subrange. For example, if we need a signal that is 1-10V (1V corresponds to zero
power, 10V corresponds to full power) then we set 10-100%. Similarly if we need a signal that is 2-5V
(2V corresponds to zero power, 5V corresponds to full power) then we set 20-50%. The output within
this range is linear and even for the smallest possible subrange (10% of the full range, so eg. 10-20% ie.
1-2V) is fine enough and has minimum resolution of 100 levels (for smallest subrange of 1V it means
the resolution is 10mV).
