Over speed

Over speed of the motor has been the most frequent cause for winch breakdowns. Therefore it is of utmost importance to protect the motor against overspending.

Over speed occurs when the load on the wire/chain surpasses what the motor can pull/hold and the drum starts uncontrolled to pay out.

The winch is protected against over speed in the following way:

1.When pay out speed exceeds 100 %. Full water-brake in stead of 50% electrical brake. Automatic return to 50% electrical brake and 50 % water brake when speed less than 100 %.

2.When pay out speed exceeds 105 %. Band brake is applied with 50 % Opens automatically when pay out speed less than 100 %.

3.When pay out speed exceeds 110 %. Band brake is applied 100 %.

4.When pay out speed exceeds 120 %. Shut down. The disc brake is applied and the motor remains electrical braked until balance or break down of the winch.

Water brake

The water brake is installed as a supplement to the motor brake in order to prevent “over speed” of the motors.

Due to the characteristics of the water brake it will work as a brake amplifier when the braking power of the electrical motor starts to give in.

The winch motor has great braking effect at low rpm whereas the water brake has very little effect. With higher rpm the braking effect of the water brake increases and the total outcome of the characteristics is very great.

Electrical brake (Resistor banks)

Resistor banks have been installed to absorb the current generated during pay out. Part of the current will be supplied to the circuit-reducing load on shaft generators but in situations with too small consumption to absorb the generated current it has to be “burnt off” in the resistor banks.

The shaft generators are protected from return current and can not receive current from the main switchboard.

The resistor banks are clutches in steps according to requirement.

Band brake

The winch is equipped with a band brake that works directly at the drum. This band brake ensures that the drum is unable to rotate when the handle is in zero as well as when changing modes.

If a drum is able to rotate while changing mode it can lead to a break down. 50% of the brake force comes from springs built in to the brake cylinder and the last 50% from hydraulic pressure.

The band brake is activated via a hydraulic power pack supplying power to the hydraulic cylinder of the brake.

“Band brake mode” is used if you want to control a payout without damaging the motor with over speed.

In this mode the drum is de-clutched only being braked by the band brake. The band brake is set to maximum holding power (less 2 %) which closes the brake almost 100 %. Then the band brake can be adjusted to tension wanted.

The tension controller can be set from 0 % to 100 % where 0 % means brake fully closed and 100 % means brake fully open in which case the drum is free to rotate.

Spooling of wire

When spooling of wire it is of utmost importance that the wire is spooled correct. There is no automatic spooling device as the wires are of different types and dimensions. Furthermore care has to be exercised when spooling connections such as shackles on the drum as these can damage the wires. Care must also be exercised specially when spooling long wires as it is very important these are spooled on very tight to prevent the wire to cut into lower layers when tension increases.

The length of the wire is measured with raps on the drum and if the wire is not spooled correct the figure showing wire length on the SCADA monitor will be wrong.

“The spooling device” can be damaged if the guide rollers are not opened sufficiently when a connection is passing through. It is very important always to keep an eye on the wire and the drum.

It may be difficulty to get used to operate the winch using cameras but usually it quickly becomes natural. Cameras are located in different places in the winch garage giving opportunity to watch the desired winch drum from different angles.

Adjustment of motor torque

The torque of the motors can be adjusted (HT control). This can be utilised when working with wires of smaller dimensions which can easily be broken by the power of the motors.

The torque can be adjusted to correspond with the breaking load of the wire. It is done with a pot-meter on the winch control panel. The torque can be adjusted between 0 % and 100 %. Normally the HT controller is set at 100 %. Care must be exercised when adjusting below 100

% as the holding power is reduced and case the wire is strong enough there is a risk of over speed or other malfunction – shut down of the system.

Tension control:

To be used during chasing out of anchors.

By pressing “CT ON” once the winch is in chasing mode, and the required tension are to be set on CT-Potentiometer. During chasing out to anchor the winch will start paying out when the actual tension is more then the adjusted tension.

QUICK & Full Release

At quick release the following actions will be executed automatically.

Preparation: Quick releases (quick release push button pressed).

a)Hydraulic accumulator 1 and 2 (solenoid KY1 andKY2) on.

b)Band brake closed to 100 % and de-energise the active motor(s) in order to get the active clutch out while the belonging disk brake(s) are lifted. The quick release procedure will be continued if the winch is clutched out.

Execution quick release when clutch is out (quick release push button remains pressed):

a)Disc brake closed

b)Band brake closed to 7% when pressing the quick release button only.

c)Band brake 100%open when pressing the quick release and the full release button both.

Stop quick release (quick release push button released):

a)Band brake closed to 100% when the hydraulic pump is running or to 50% when the hydraulic pump is not running. (Spring operation only).