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10. Continue to fill in coolant until a base pressure of 100...150 kPa is achieved.
11. Open the bleed valve of the pump to allow any air out.
12. Re-check the pressure and add coolant if necessary.
13. Start the coolant pump. Let any air remaining in the system out through the
14. After one to two minutes, stop the pump or block the coolant flow with a valve.
15. Re-check the pressure and add coolant if necessary.
16. Repeat steps 13 to 15 a few times until all air is let out of the cooling circuit.
Draining the internal cooling circuit
The internal cooling circuit can be drained through the drain valves in each cubicle.
The power modules in any cubicle can be drained without draining the whole internal
cooling circuit.
WARNING! High-pressure warm coolant may be present in the internal cooling
circuit. No work on the cooling circuit is allowed until the pressure is lowered down
by stopping the pumps and draining coolant.
1. Lead the bleed and drain hoses to buckets or other suitable containers. Extend
the standard hoses if necessary.
Note: Draining propylene glycol into the sewer system is not allowed.
2. Open the bleed valves to let air displace the liquid.
3. If required, dry the piping with compressed oil-free air of less than 6 bar.
4. If the drive is to be stored in temperatures below 0 °C (32 °F),
• dry the cooling circuit with air
• fill the cooling circuit with a mixture of water, corrosion inhibitor and DOW
Propylene Glycol according to
• drain the cooling circuit again.
Adding inhibitor
Add inhibitor in the internal circuit every second year. The amount to be added is
0.5% of the total coolant quantity in the circuit. Use e.g. Cortec VpCI-649 (by Cortec
Corporation, www.cortecvci.com).
Internal cooling circuit
bleed valve at the cooling unit.
Listen for a humming sound and/or feel the piping for vibration to find out if there
is still air left in the circuit.
Freeze protection and corrosion inhibition
below.
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