Technical Support

F.A.Q.S.

How do I contact ZDS Customer Service?
You can contact ZDS directly or refer to your specialist wholesaler or local distributor.

What can I do with ZDS submersibles pumps?
ZDS submersibles pumps are designed to be used in following applications:

Where are the ZDS products manufactured?
All ZDS products are designed and produced in Padova, Italy.

What is the total delivery head?
The dynamic total delivery head is also referred to as the "delivery head" or simply as the "total delivery head". The delivery head is equal to the pressure measured at the discharge port minus the inlet pressure applied at the suction port. The delivery head is generally specified in m. Generally speaking, the delivery head is represented together with the flow rate in the form of the QH curve.

What is a performance curve and what is its importance?
The pump's input power is the pump's power requirement under the present operating conditions. The rated motor output, including the operating factor, must be equal to or greater than the pump's power requirement. If the pump's power requirement is greater than the rated output of the motor, the motor is drawing more current than intended. This leads to overheating of the motor, and potentially damages it.

Why do I have to follow the instructions to install ZDS products?
It is absolutely recommended. The installation and operating instructions of ZDS products contain basic instructions which must be followed in connection with the installation, operation, and maintenance of the system. Moreover, they must be read by the installer and the relevant personnel/owner prior to installation and commissioning. In addition, they must be available to personnel on site at all times.

In which position can ZDS pumps operate?
ZDS pumps  can operate in vertical or horizontal position. When the pump is installed horizontally, the delivery outlet shall be upfaced and the inlet of the pump must always be completely submerged in the water. For your convenience, ZDS has designed a special KIOS Kit accessory for horizontal installation in water tanks.

What types of liquid can I pump with a ZDS pump?
Clean water, free of solids and abrasives, non-viscous, non-aggressive, non-crystallised and chemically neutral.

How do I install the underwater supply cable of ZDS motor?
It is recommended that the cable plug is clean and dry, before installing the underwater supply cable on the motor. For ease of installation, the rubber parts of the cable plug should be coated with a non-conductive silicone paste. The screws that hold the cable in place should be tightened and secured with threadlock.

Can a ZDS three-phase pump be connected to a single-phase power supply?
No, it can't. A ZDS three-phase pump has to be connected to a three-phase power supply. It is exactly the same for a ZDS single-phase pump that has to be connected to a single-phase power supply.

Can a ZDS hydraulic part operate at 60 Hz?
ZDS hydraulic part is designed to operate at 50 Hz, but can also operate at 60 Hz. In this case, the motor will absorb much more power; therefore it will be necessary to install a more powerful motor.

Can ZDS motors and sumbersible pumps operate at 60 Hz?
No, ZDS motors and submersible pumps are designed to operate at 50 Hz, n- 2850 min-1.

Can ZDS products operate with a frequency converter?
The only ZDS products that can operate with a frequency converter, according to current regulations are: the OT three-phase motor and the O3 single-phase PSC motor, when not equipped with ZDS DRP device. The technical information set out in the operating instructions and datasheet should be referred to in each individual case.

Are ZDS motors equipped with soft-start system?
Plug&GO® and H2E motor come with an integrated soft-start functionality to reduce start-up current.

How many starts/hour are allowed without compromising the service life of the ZDS pump?
The maximum number of starts per hour is 150, equally distributed.

Is there Glycol inside ZDS products?
In order to protect against frost damage during transport and storage, Plug&GO pump, H2E and H2 motors are filled by a water/glycol mixture. Glycol substance is classified as not toxic and into water hazard class ‘1’ (WGK 1 = slightly hazardous to water). Please check if the regulations of your district-level water require the motor fluid to be completely glycol-free before installing the pump.

Why is it important to prevent dry-running?
A pump which runs dry has a higher risk to break as internal components of pump and motor could be damaged. For this reason, ZDS offers many electronic devices to protect the pump against dry-running. Plug&GO pumps and H2E complete solution already comes with a built-in dry-running protection system. DRP device integrated in the supply cable can be installed on ZDS or Franklin motors. It is recommended to select the correct pump considering the delivery provided from the well, in order not to install an oversized pump for that system. The actual conditions prevailing in the application in question must therefore always be reconciled with the information provided in the operating instructions or the datasheet before initial start-up of the pump.

Are ZDS pumps dry-running protected?
Plug&GO pump, H2E complete solution, complete solution with Master panel, motors equipped with DRP, have integrated dry-running protection that does not require a corresponding level sensor.In case of water shortage, the system automatically stops the pump. The system restarts the pump observing a programmed time.

What are ZDS pumps working limits?
The pump must be within the technical and environmental limits given in instruction manuals and technical catalogues.

What are ZDS pumps working tolerances on the performance?
The performance of ZDS electric pumps provided is in accordance with UNI EN ISO 9906 Appendix A for pumps produced in series.

What happens if the pump is operating too far to the left on the curve?
If the pump is operating too far to left on the curve, this means that the pump is delivering high pressure but at a flow rate that is low or non-existent. High pressure inside the pump stresses the impeller unit and thus increases pressure on the motor bearings. In the extreme case, this will cause damage to the pump and motor. If the flow rate is below the minimum flow rate required for the pump, the pumped medium may also overheat and damage the pump. For this reason, the pump must always be operated inside the lower and upper flow rate bounds. Ideally, the pump should be operated as close as possible to the point of optimal efficiency in order to ensure a long service life and in order to minimise energy consumption.

What happens if the pump is operating too far to the right on the curve?
When a pump operates too far to the right on the curve, the pump is delivering a flow rate greater than that for which it was designed. In other words: the pump is too small for the volume flow needed by the system. Operating the pump in this range may cause damage to the pump and the motor. The pump must always be operated within the lower and upper flow rate bounds. Ideally, the pump should be operated as close as possible to the point of optimal efficiency in order to ensure a long service life and in order to minimise energy consumption.

What is downforce, and what causes it?
Downforce is a downwardly directed force acting on the pump's impeller/shaft unit during operation. Most pumps and motors are designed so that a downforce must always be present during operation. However, downforces that are too high may also lead to problems, if for instance the pump is operating at a duty point with a low flow rate and thus high delivery pressure. In the event of continuous operation in this range, the motor's axial bearing may be damaged. Furthermore, the pump and motor may overheat due to the absence of sufficient cooling flow. In order to prevent these problems from occurring, the pump must be operated within the specified flow rate range. The curves for ZDS submersible pumps represent the permitted flow rate range in the form of a solid line, with the impermissible operating range shown as a dashed line.

What is water hammering, and what causes it?
Water hammer is a pressure surge caused by a rapid change of water velocity in a piping system. Water hammer is often accompanied by a sound comparable to a hammer hitting a pipe, hence the name. In water well systems, water hammer is typically caused when:

  1. the check valve installed in the drop pipe nearest the pump is more than 9 m above the standing water level, or
  2. the check valve installed in the drop pipe leaks while the next check valve above holds.

In both situations a partial vacuum is created in the drop pipe. On the next pump start, water moving at very high velocity fills the vacuum and strikes the closed check valve and the stationary water in the pipe above it, causing a pressure surge and hydraulic shock. This shock can split pipes, break joints and damage the pump and/or motor. When discovered, the system should be shut down and the pump installer contacted to correct the problem.

What is a water-cooled motor?
In this motor design, all rotating parts (shaft, rotor) are located within the can in the pumped liquid. Cooling and lubrication is provided by the pumped liquid.

Why is the ZDS pump making noise?
The pump is noisy because:

What could be the cause of the tripping of circuit breakers on the motor starter or of the fuses?
Circuit breakers and fuses could trip for various reasons:  incorrectly designed circuit breaker or fuses, too low a setting for the motor-protective circuit breaker, undervoltage, asymmetric three-phase current, short circuit on the motor, incorrect wiring or faulty electrical connections, worn or blocked pump, defective capacitor for single-phase motors, motor-protective circuit breaker exposed to a higher ambient temperature than the motor. However, the pump may also be undersized for the application in question, and may be operating in excess of its nominal flow rate. In this case, try to partially close the shut-off valve on the pressure side in order to throttle the flow rate until the motor current returns to within the acceptable limits.

What might be the cause of the tripping of the circuit breake or fuses?
Circuit breakers and fuses could trip for numerous reasons: incorrectly designed circuit breaker or fuses, too low a setting for the motor-protective circuit breaker, undervoltage, asymmetric three-phase current, a short circuit on the motor, incorrect wiring or faulty electrical connections.

What is the maximum sand content of pumped water?
The maximum sand content of the water may not exceed 120 g/m<sup>3</sup>. A greater sand content reduces the service life (due to abrasion of the internal components) of the pump and increases the risk of pump blockages.

What is a cooling jacket?
A cooling jacket, is a system that ensures there is always sufficient water flow across the motor surface in order to cool the motor. In a typical well installation, the pump is surrounded by the walls of the well. The motor is installed below the pump. Because the pump draws in water from below, the water flows along the well walls and over the surface of the motor, cooling the motor in so doing. If the pump is installed in wide wells, open water, tanks, there will be no well walls to guide the water flow over the surface of the motor, thus necessitating a cooling jacket. ZDS Kios Kit is highly recomended, in this cases, to guarantee the correct cooling flow.

What is the minimum flow rate required for ZDS submersible pumps?
While operating the pump, an uninterrupted minimum flow rate of minimum 8 cm/sec is required in order to sufficiently cool down the pump and the motor.

What minimum fill level is required to properly operate the ZDS pump?
ZDS motors are designed to be cooled down by the surrounding pumped water (minimum cooling flow for ZDS motor is 8 cm/sec). In order that the motors to be adequately cooled, ZDS pumps must always be completely submerged in the pumped water during operation. If the minimum cooling flow is not guaranteed we recomend to use ZDS Kios Kit or a cooling jacket.

What leads to overheating of motors?
This can be caused by a number of reasons:
too much sand or impurity in the pumped liquid, the pump working in shut-off, undervoltage or overvoltage, asymmetrical three-phase current, diminishing insulation resistance, too many starts/stops, flow rate too high or too low, high resistance to rotation due to damaged pump, high viscosity or density of the pumped liquid, clogged or blocked pump. Most of these problems can be avoid thanks to ZDS electronic devices which protect pump and motors from possible damages.

What should be done if the pump motor's current exceeds full load current?
There are several reasons why the permitted full load current could be exceeded when operating the pump: undervoltage, current imbalance in three-phase motors, motor has a short circuit, incorrect wiring or faulty electrical connections, viscosity or density of the pumped medium too high, or the pump is worn or blocked. However, the pump may also be undersized for the application in question, and may be operating in excess of its nominal flow rate. In this case, try to partially close the shut-off valve on the pressure side in order to throttle the flow rate until the motor current returns to the acceptable limits.

How will the ZDS motor react to voltage fluctuations?
Nominal voltage can be read on the nameplate with these variations:
-10%/+6% among of the nominal voltage of each model. The motor protects itself by shutting off below and above these limits, with automatic restart when the voltage gets within them again.

How reliable is the capacitor built in to the 2-wire motors?
The capacitor is guaranteed for a minimum of 30'000 hours of operation. Over the last 3-years, ZDS had a failure rate of less than 0,2% due to the capacitor built-in the 2-wire motors.

How do you select the correct control panel for a ZDS submersible pump?
The correct control panel must be selected according to motor type (oil-cooled or water-cooled), supply mode (single-phase, three-phase), voltage type (220-230V, 380-415V), motors' power (kW).

Where can I find information to troubleshoot ZDS products?
The operating instructions provided with every ZDS product contain relevant troubleshooting information. These instructions describe not only installation, operation and maintenance, but also include a dedicated section to assist in troubleshooting general problems that arise during use.
In case you can't find the answer you are looking for, please contact ZDS customer service or your local distributor.