Maintenance; Mechanical Settings; General; Contact Settings - GE MFAC 14 User Manual

Section 3.

MAINTENANCE

Periodic maintenance is not necessary. However, periodic inspection and test is
recommended. This should be carried out every l2 months or more often if the relay is
operated frequently or is mounted in poor environmental conditions.
3.1 Repeat secondary injection tests 2.2.4 to prove operation, with emphasis on
contact wear and condition. Mechanical settings may be checked against those
shown in Section 4.
Section 4.

MECHANICAL SETTINGS

4.1

General

Armature gap measurements should be made with the top of the feeler gauge
level with the centre line of the core.
Contact pressures are measured with a gramme gauge at the contact tips.
In general contact gaps and follow through are defined by quoting an armature gap
at which the tips should be just closed or just open.
The relay contact state is always defined with the relay in the unenergised
position, unless otherwise specified on the appropriate circuit diagram.
4.1.1 With the armature closed the clearance between the back of the armature and
the back stop should be 0.003"/0.008".
4.1.2 Nominal armature gap open: 0.060" for all types.
Set screw in armature so that armature gap when closed is approximately
0.005"/0.010".
4.2

Contact settings

4.2.1 Normal duty make contacts
With the armature closed onto a 0.011" feeler gauge the make contacts should be
closed, but should be open using a 0.013" feeler gauge.
Contact settings
Force to just close the
make contacts
Force to just lift the fixed
contact off its support
Nominal contact gap 0.060"/0.080"
4.3

Mechanical flag settings

4.3.1 Settings for self reset units
MFAC l4/34
With the armature closed on to a 0.013" feeler gauge the flag should be free to fall,
but should not fall using an 0.018" feeler gauge. Adjustment is made to the catch
spring on the flag.
2 contacts
(MFAC 34)
20/25 grams
15/20 grams
18
4 contacts
(MFAC 14)
15/20 grams
20/25 grams