English
18
WILO SE 05/2012
6
Description and function
6.1 Description of the pump
The pump (Fig. 1A RKA/RKC model, Fig. 1B PWM model) consists of a hydraulic
system, a glandless pump motor with a permanent magnet rotor, and an elec-
tronic control module with an integrated frequency converter. The control
module can have either a operating knob (self regulated pump RKA/RKC model)
or speed control by an external PWM signal (PWM model). Both models are
equipped with a LED display in order to display the pump operating status (see
paragraph 10).
6.2 Functions
All functions can be set, activated or deactivated by using the operating knob or
by an externally controlled PWM signal.
Settings via operating knob
Variable differential pressure
(
Δ
p-v):
The differential-pressure setpoint H is increased linearly over the permitted
volume flow range between ½H and H (Fig. 3a). The differential pressure gen-
erated by the pump is adjusted to the corresponding differential-pressure set-
point. This control mode is especially useful in heating systems with radiators,
since the flow noises at the thermostatic valves are reduced.
Constant differential pressure (
Δ
p-c):
The differential-pressure setpoint H is kept constant over the permitted volume
flow range at the set differential-pressure setpoint up to the maximum pump
curve (Fig. 3b). Wilo recommends this control mode for underfloor-heating cir-
cuits or older heating systems with large-sized pipes as well as for all applica-
tions with no changeable pipe system curve, e.g. boiler charge pumps.
Venting function (RKA model):
During automatic venting function (10min) the Pump runs alternately with high
and low speeds to help air bubble from the pump to agglomerate and to lead
direct to the venting valve of the installation.
Constant speed I, II, III (RKC model)
The pump is operating continuously with the preset speed (Fig. 3c)
External control via a PWM signal (PWM model)
The actual/setpoint level assessment required for control is referred to a remote
controller. The remote controller sends a PWM signal as an actuating variable to
the Pump.
The PWM signal generator gives a periodic order of pulses to the pump (the duty
cycle), according to DIN IEC 60469-1. The actuating variable is determined by
the ratio between pulse duration and the pulse period. The duty cycle is defined
as a ratio without dimension, with a value of 0 … 1 % or 0 … 100 %. See PWM
signal logic 1 (heating) fig. 3d and PWM signal logic 2 (solar) fig. 3e.
om_yonos_para_oem__4523676_01__1205_de_en_fr.book Page 18 Tuesday, May 22, 2012 1:49 PM
