Page. 22 of 29
March 2016
Edition 1
PLANAR
4) Check the performance of the speed measurement channel. To do this, connect
the contacts of blue and black wires (Figure 12), and measure the pulse frequency on the
green wire with a digital tester. When the AB is gaining speed, the pulse frequency
should increase. Open the contact. The AB will start to slow down, and the pulse rate
will begin to decline. If any of these conditions is not met, the AB is faulty.
Fig.12–Control signal (PWM) connections in motor testing.
In case of failure of the electric motor or the impeller (the impeller touches the
volute), it is necessary
to replace the whole air blower with a new one
.
If the fault persists with the new AB, check the CU.
5.7 Functions, Removal and Replacement of Control Unit.
CU provides control of the heater, together with the controller.
CU performs the following functions:
а) initial assessment (check of readiness for work) of the heater components at
startup;
b) assessment of how the heater components function during operation;
c) heater startup;
d) heater shutdown:
-
on command from the controller;
-
in case of failure of one of the controlled components;
-
when the controlled parameters go beyond the permissible limits
(temperature, voltage);
-
in case of flameout in the combustion chamber.
When a malfunction of the CU is detected, make sure that connecting cables, wires
and connectors of the heater have no faults. Check the controller. Replace the CU with a
known-good CU. If after replacing the CU the heater becomes operational, the old CU is
considered inoperative and should be replaced.