Field Wiring; Motor Protection - Grundfos CR Series Installation And Operation Manual

Electrical
WARNING
THE SAFE OPERATION OF THIS PUMP REQUIRES THAT IT BE GROUNDED IN ACCORDANCE WITH THE NATIONAL ELECTRICAL CODE AND LOCAL
GOVERNING CODES OR REGULATIONS. CONNECT THE GROUND WIRE TO THE GROUNDING SCREW IN THE TERMINAL BOX AND THEN TO
ACCEPTABLE
THE
All electrical work should be performed by a qualified electrician in accordance with the latest edition of the National Electrical Code, local codes and
regulations.
Motor
Grundfos CR pumps are supplied with heavy-duty 2-pole (3600 RPM nominal), ODP or TEFC, NEMA C frame motors selected to our rigid
specifications. Motors with other enclosure types and for other voltages and frequencies are available on a special-order basis. CRN-SF pumps are
supplied with an IEC (metric) type motor with a reverse thrust bearing. If you are replacing the pumping unit, but are using a motor
previously used on another CR pump, be sure to read the "Motor Replacement" section on page 10 for proper adjustment of the coupling height.
Position of Terminal Box
The motor terminal box can be turned to any of four positions in 90° steps. To rotate the terminal
box, remove the four bolts securing the motor to the pump but do not remove the shaft coupling;
turn the motor to the desired location; replace and securely tighten the four bolts. See Figure 4.

Field Wiring

Wire sizes should be based on the current carrying properties of a conductor as required by the
latest edition of the National Electrical Code or local regulations. Direct on line (D.O.L.) starting is
approved due to the extremely fast run-up time of the motor and the low moment of inertia of
pump and motor. If D.O.L. starting is not acceptable and reduced starting current is required, an
auto transformer, resistant starter or soft start should be used. It is suggested that a fused
disconnect be used for each pump where service and standby pumps are installed.

Motor Protection

1. Single-Phase Motors:
With the exception of 7 1/2 and 10 HP motors which require external protection, single-phase CR pumps are equipped with multi-voltage,
squirrel-cage induction motors with built-in thermal protection.
2. Three-Phase Motors
CR pumps with three-phase motors must be used with the proper size and type of motor-starter to ensure the motor is protected against
damage from low voltage, phase failure, current imbalance and overloads. A properly sized starter with manual reset and ambient-
compensated extra quick trip in all three legs should be used. The overload should be sized and adjusted to the full-load current rating of the motor.
Under no circumstances should the overloads be set to a higher value than the full load current shown on the motor nameplate. This will void the
warranty. Overloads for auto transformers and resistant starters should be sized in accordance with the recommendations of the manufacturer.
Three phase MLE motors (CRE-Pumps) require only fuses as a circuit breaker. They do not require a motor starter. Check for phase imbalance
(worksheet is provided on page 15).
NOTE: Standard allowable phase imbalance difference is 5%.
3. CRN-SF
The CRN-SF is typically operated in series with a feed pump. Because the maximum allowable inlet pressure of the CRN-SF increases from 73 psi
(when pump is off and during start-up) to 365 psi (during operation), a control device must be used to start the CRN-SF pump one second before
the feed pump starts. Similarly, the CRN-SF must stop one second after the feed pump stops.
GROUNDING POINT.
Motor Terminal Box Positions
(Top View)
Figure 4
7