Labconco PURICARE Procedure Station Models 34812xx - Manual (Page 150)

Page 150 of 197
6. Next, connect the meters + DC voltage lead to pin 6 (yellow wire) and verify
there is ± 24 Volt DC ± 5 Volts DC, as shown in Figure 9-12. The presence of
24 Volt DC on this yellow wire tells the motor to start.
Figure 9-12
Measuring 24 VDC voltage
7. Next, move the meter’s + DC voltage lead to pin 5 (purple wire) [the meter’s lead
is still connected to pin 8 (brown wire)]. Note the DC voltage, since the motor’s
speed is determined by the pulse width modulated signal on this contact. A
voltage noted in step 6 signifies 100% pulse width duty cycle, while a DC voltage
of 0 volts would indicate a 0% PWM level. Depending on the particular ECM
motor, the motor speeds for the 0% PWM levels and 100% PWM levels will differ
but the 0% level represents the “night setback” blower speed and the 100% level
indicates the max speed ever required by the motor under total filter loading. The
actual DC voltage measured will be between 0 V and 24 Volts DC, and that voltage
indicates roughly the % duty cycle being sent to the motor at this time. For
example:
A total voltage of 22 VDC, and a signal voltage of 15 VDC would indicate 15 VDC
measured/22V DC @ 100% = 68% duty cycle.
Another example, would be 18 VDC/22 DC @ 100%, would correspond to an 81%
PWM signal. Refer to the QuickCharts to find the nominal PWM for new filters
based on cabinet width and sash height. Verify the PWM is near the value in the
QuickCharts.