MICROPUMP, INC.
A Unit of IDEX Corporation
PO Box 8975, Vancouver, WA 98668-8975 • Phone: 360/253-2008 • Fax: 360/253-8294
MICROPUMP
LIMITED
A Subsidiary of Micropump, Inc.
2 Howard Road, Eaton Socon, St.
Neots, Cambridgeshire, PE 19 8ET England, • Phone: 011-44-1480-356600 • Fax: 011-44-
1480-
356300
Page 17 of 33
2.4.3 Motor Winding Test
2.4.3.1 Measure the resistance of each motor winding with an ohmmeter. Each
phase-to-phase should measure 53 ohms with no more than 15%
variation between windings. If any measurement is out of specification,
refer to Troubleshooting.
TROUBLE
POSSIBLE CAUSES
CORRECTION
(a) Unit fails to shut off at 23
psi (1.59 bar)
(a1) Pressure switch
assembly out of
adjustment or bad.
Check and adjust pressure
switch assembly or replace
defective parts as required.
Check and adjust pressure
regulator.
(b) Unit fails to shut off
between 4 to 8 psi (.28 to .56
bar).
(b1) Pressure switch out of
adjustment or bad.
Check and adjust. Replace
defective parts as required.
(c) Back flow through pump
with system pressure below
30 psi (2.07 bar)
(c1) Over - pressure re-lease
setting out of adjustment.
(c2) Over-pressure release
setting parts worn.
Check and adjust setting.
Check and replace worn parts.
(d) Unit decouples
(d1) Drive magnet mis-
adjusted
(d2) Drive magnet rubbing on
cup.
(d3) Friction on impeller gears.
(d4) Friction in pump
assembly bushings.
(d5) Driven magnet rubbing on
cup.
Check and adjust.
Check and adjust. Replace
defective parts as required.
Check and replace as
required.
Check and replace as
required.
Check and adjust. Replace
defective parts as required.
(e) Circuit breaker trips.
(e1) Incorrect electrical
connections.
(e2) Insulation breakdown in
motor.
Check and correct as required
Check and replace motor and
drive housing with pressure
switch.
(f) Motor runs slowly
(f1) Bad winding.
(f2) Drive Magnet rubbing on
cup.
Check and replace motor and
drive housing with pressure
switch.
Check and adjust. Replace
defective parts as required.
(g) Incorrect winding
resistance.
(g1) Short or open in one or
more legs.
Check and replace motor and
drive housing with pressure
switch.
2.5 Troubleshooting
