Howard SVR1 Regulator - Manual (Page 15)

Switch-Pad™ SVR-1 Step Voltage Regulator
Document No. 2.4.114
Revision: 03
Issued: March, 2012
15 Copyright © 2012 Howard Industries, Inc.
before beginning untanking procedures.
• Remove the control cable from the terminal block
enclosure and, if necessary, the control box from
the tank.
• Loosen the cover band and remove it from the
regulator.
• The regulator can now be removed from the main
tank using the cover lifting eyes (Figure 11).
2. Check to verify all hardware and connections are
tight.
3. Check the condition of wire insulation, looking for any
cracks or other deterioration.
4. Inspect the tap changer’s arcing contacts to verify
operational condition. Since numerous factors affect
a contact’s wear rate, no single criteria can be used
to predict a contact’s remaining life and the need to
replace it. Refer to “Maintenance Instructions, TC-1
and TC-2 Load Tap Changer” (Document 2.4.58) and
follow the recommended procedure for inspection
and maintenance of the load tap changer switch
mechanism.
5. Reinstall the regulator’s internal assembly using the
reverse procedure. After the inspection is completed,
the regulator can be safely returned to service
according to the procedure discussed on pages 10
and 11.
VACUUM OIl FIll PROCESS
This procedure applies if the oil level in the regulator has
been lowered to a level that exposes part or all of the
coils to air or the internal assembly has been removed
from the tank.
1. Every container or tote of transformer oil used in
the filling process should be visually inspected and
tested for water or other possible contaminants
before proceeding with the filling process.
2. If the coils are out of oil for more than four hours,
the coils must be baked for at least 24 hours at a
temperature of 100°C (212°F) prior to re-tanking
the internal assembly. The tap changer must not be
exposed to a temperature above 110°C (230°F).
The unit should not be re-baked more than two
times.
3. Connect the vacuum pump suction line to the
pressure-vacuum fitting near the top of the tank.
MAINTENANCE (Continued)
FIGURE 11:
4. Connect the oil fill line to the tank at the bottom drain
valve connection.
5. Start the vacuum pump.
6. When the vacuum level inside the tank reaches 2000
microns (2 Torr) start timing. When this vacuum level
has been maintained for a minimum of 1 hour the oil-
filling may be started.
7. Continue to fill the unit until the oil level fills the sight
glass (25°C oil level).
8. After the oil filling has been completed, continue to
hold the vacuum level for 1 additional hour.
9. If vacuum oil filling is not possible, the re-tanked
internal assembly should be allowed to soak in oil for
at least five days before energizing.
COOlING FANS
Cooling fans (when present) have sealed bearings and do
not require maintenance.