Frequently Asked Questions (Faq) - Danfoss AK-PC 551 Technical Brochure

Frequently asked questions (FAQ)

Question Solution
How to connect The analogue outputs AO3 and AO4 of the AK-PC 551 pack
variable speed drive controller is galvanic separated from the other inputs and outputs
(VSD)? of the controller� So if the AK-PC 551 controller is ordered for 24Vac
supply voltage, you can use the same 24Vac transformer for power
supply of the controller and for supply of the analogue outputs�
It is recommended to use a double isolated transformer (Class II) as
this type does not need to be connected to protective earth on the
secondary side� This will prevent any ground loops between the
AK-PC 551 pack controller and the variable speed drive connected
to AO3 or AO4�
How to connect the The Pulse Width Modulated valve (PWM) of a digital scroll
PWM valve of a digital compressor must be connected to one of the solid state relays
scroll compressor? (SSR) of AK-PC 551 - which are the outputs DO5 or DO6� The PWM
valve function cannot be selected for any of the other digital
outputs�
The PWM valve of the digital scroll compressor works in such a
way that when voltage is supplied to the valve, the digital scroll
compressor is unloaded and when no voltage is supplied to the
valve, the digital scroll compressor is loaded�
When the PWM valve signal is selected for DO5 or DO6, the
polarity of the output signal is by default inverted and thereby
the PWM valve of the digital scroll compressor can be connected
directly to the AK-PC 551 without any intermediate relays�
22 Technical brochure RC8CF102 © Danfoss 08-2014
Example: Variable speed drive connected
to AO3
Example: Wiring of PWM valve of digital
scroll compressor to DO5/DO6 of AK-PC
551
AK-PC 551