Warner Electric SFC-1525 - Manual (Page 7)

7 Warner Electric • 800-825-9050 P-207 • 819-0516
Where units are used near gear boxes or transmissions
requiring frequent lubrication, means should be pro vid ed
to protect the friction surfaces from oil and grease to
pre vent serious loss of torque.
Oil and grease accidentally reaching the friction surfaces
may be removed by wiping with a rag dampened with a
suitable cleaner, which leaves no residue. In performing
this operation, do not drench the friction material.
If the friction materials have been saturated with oil or
grease, no amount of cleaning will be completely
ef fec tive. Once such a unit has been placed back in
service, heat will cause the oil to boil to the surface,
resulting in further torque loss.
Torque Loss: If a brake or clutch slips or loses torque
completely, the initial check should be the input voltage
to the field as follows:
90-Volt Series: Connect a DC voltmeter with a range of
0-100 or more directly across the field terminals. With
the power on and the potentiometer turned up, a normal
reading is 90 volts, although 85 to 95 is satisfactory. The
reading should drop as the potentiometer control is
ad just ed counterclockwise.
24-Volt Series: Use a DC voltmeter with a range of 0-30
volts or more. A normal reading is approximately 22-26
volts.
Use a DC voltmeter of approximately 0-15 volt range.
A normal reading is from 5.5 to 6.5 volts.
The above checks normally are sufficient. Further
checks may be made as follows: a low range ammeter,
when connected in series with one field lead, will
normally in di cate approximately .40 amperes for the 90
volt units, 1.0 ampere for the 24 volt, and 3.5 amperes
for the 6 volt series. These readings are with the power
on and the potentiometer control in the maximum
position.
Ohmmeter checks should be made with the power off
and the circuit open (to be certain, disconnect one lead
to the field). Average resistance for the 90 volt series is
220 ohms; for the 24 volt, 20 ohms; and for the 6 volt
series, 1.5 ohms. A very high or infinite resistance
read ing would indicate an open coil.
If the above checks indicate that the proper voltage and
current is being supplied to the magnet, mechanical
parts should be checked to assure that they are in good
op er at ing condition and properly installed.