Sime MURELLE HR 50 R, Installation And Servicing Instructions, Page: 42 / 60

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5 FAULT FINDING
If an electrical fault occurs on the appli-
ance the preliminary electrical system
checks must be carried out first.
When any service or replacement of elec-
trical components which has required
the breaking and re-making of electrical
connections has taken place, the follow-
ing tests must be repeated:
– earth continuity;
– short circuit;
– polarity;
– resistance to earth.
5.1 EARTH CONTINUITY CHECk
Appliances must be electrically discon-
nected, meter set on Ω (ohm) x 1 scale
and adjust zero if necessary. Tests leads
from any appliance earth point (e.g.
inside control box) see wiring diagrams
(section 7) to earth pin on plug.
Resistance should be less than 1 Ω
(ohm). If the resistance is greater than 1
Ω (ohm) check all earth wires for conti-
nuity and all contacts are clean and tight.
If the resistance to earth is still greater
than 1 Ω (ohm) then this should be inves-
tigated futher.
5.2 SHORT CIRCUIT CHECk
Switches turned FULL ON - meter set on
Ω (ohms) x 1 scale. Test leads from L to
N on appliance terminal block, if meter
reads 0 then there is a short circuit.
Meter set on Ω (ohm) x 100 scale. Repeat
it with leads from L to E. If meter reads
less than infinity (∞) there is a fault.
NOTE: Should it be found that the fuse
has failed but no fault is indicated, a
detailed continuity check (i.e. by discon-
necting and checking each component)
is required to trace the faulty compo-
nent. It is possible that a fault could
occur as a result of local burning/arc-
ing but no fault could be found under
test. However, a detailed visual inspec-
tion should reveal evidence of burning
around the fault.
5.3 pOLARITY CHECk
Appliance reconnected to mains supply
and meter set on 300 V ac scale. Test at
appliance terminal block.
– Test leads from L to N meter reads
approx.: 240 V ac.
– Test leads from L to E “ ” meter
reads approx. 240 V ac.
– Test leads from N to E “ ” meter
reads from 0 to 15 V ac.
5.4 RESISTANCE TO EARTH CHECk
Appliance must be disconnected from
main supply and meter on Ω (ohm) x 100
scale.
All switches including thermostat on test
leads from L to E - if meter reads other
than infinity (∞) there is a fault which
should be isolated.
A detailed continuity check is required to
trace the faulty component.
ImpORTANT:
These series of checks are the first
electrical checks to be carried out
during a fault finding procedure. On
completion of the service/fault finding
task which has required the breaking
and remaking of electrical connections
then the checks 5.1 Earth continuity,
5.3 polarity and 5.4 Resistance to earth
must be repeated.