Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C Frame) - Classic Control - Manual (Page 424)

6-80 Component Definition and Maintenance
7000L-UM300I-EN-P – June 2013 7000 “C” Frame
Maintaining Coolant Ratio
Mixing pure ethylene glycol and de-ionized water produces the
coolant used as the cooling medium in the liquid-cooled PowerFlex
7000L Medium Voltage “C” Frame drive. During operation, the
concentration of pure ethylene glycol and de-ionized water may
change due to fluid leakage or evaporation; therefore, the freezing
point of the coolant may not be correct. The following instruction
detail the steps required to record and correct the freezing point of the
coolant mixture.
Required items:
 Glycol and battery tester (Part No. 80025-862-01)
 De-ionized water, 19-litre (5-gallon) container
(Part # 80025-784-60)
 Pure ethylene glycol, 19-litre (5-gallon) container
(Part # 80025-784-61)
1. Measure and record the reservoir coolant freeze point using the
Glycol and Battery Tester.
2. If the freezing point of the coolant is at -45°C (-50°F) ±2°C,
correction is not required.
3. If correction is required, then follow the remaining steps.
4. Water freezes at 0°C (32°F) and pure ethylene freezes at -13°C
(8.6°F), but mixtures of the two freeze at lower temperatures.
For example, a 50/50 mixture by weight of ethylene glycol and
water freezes at -36°C (-33°F). The addition of ethylene glycol
to the mixture will lower the freezing point. Adjust the freeze
temperature of the coolant mixture to -45°C (-50°F) using this
method.
5. Add either substance in small quantities and measure the
freezing temperature after each addition until desired freezing
temperature is achieved.
I M P O R T A N T I M P O R T A N T It is better to have more water than glycol in the
mixture because water is a better thermal
conductor than glycol.
There are two possible causes of water loss in the drive:
Evaporation – Up to 99.5% of liquid lost to evaporation is water
because of the chemical properties of the substances in the mixture.
Leaks – Glycol and water are lost proportionally depending on the
concentration of the substances in the mixture. For example, if the
mixture is 60% glycol and 40% water, then any leakage will contain
the same proportions of the liquids.
Pump Maintenance and
Replacement (cont.)