Yaskawa Z1000U - Manual (Page 240)

u Internal EMC Filter Model Installation
Internal EMC filter models (ZUoEoooo and ZUoWoooo) are tested according to European standards IEC/EN
61800-3 2nd Environment Category C2 and comply with the EMC guidelines. Refer to Enable the Internal EMC Filter on
page 77 for details about EMC filter selection and installation.
u Installing a Motor Thermal Overload (oL) Relay on the Drive Output
Motor thermal overload relays protect the motor by disconnecting power lines to the motor due to a motor overload condition.
Install a motor thermal overload relay between the drive and motor:
• When operating multiple motors on a single AC drive.
• When using a power line bypass to operate the motor directly from the power line.
It is not necessary to install a motor thermal overload relay when operating a single motor from a single AC drive. The AC
drive has UL recognized electronic motor overload protection built into the drive software.
Note: 1. Disable the motor protection function (L1-01 = 0) when using an external motor thermal overload relay.
2. The relay should shut off main power on the input side of the main circuit when triggered.
n General Precautions when Using Thermal Overload Relays
Consider the following application precautions when using motor thermal overload relays on the output of AC drives to prevent
nuisance trips or overheat of the motor at low speeds:
• Low speed motor operation
• Use of multiple motors on a single AC drive
• Motor cable length
• Nuisance tripping resulting from high AC drive carrier frequency
Low Speed Operation and Motor Thermal oL Relays
Generally, thermal relays are applied on general-purpose motors. When general-purpose motors are driven by AC drives, the
motor current is approximately 5% to 10% greater than if driven by a commercial power supply. In addition, the cooling
capacity of a motor with a shaft-driven fan decreases when operating at low speeds. Even if the load current is within the motor
rated value, motor overheating may occur. A thermal relay cannot effectively protect the motor due to the reduction of cooling
at low speeds. For this reason, apply the UL recognized electronic thermal overload protection function built into the drive
whenever possible.
Using a Single Drive to Operate Multiple Motors
Set parameter L1-01 to 0 to disable thermal overload protection for the drive.
Note: The UL recognized electronic thermal overload function cannot be applied when operating multiple motors with a single drive.
Long Motor Cables
When a high carrier frequency and long motor cables are used, nuisance tripping of the thermal relay may occur due to increased
leakage current. To avoid this, reduce the carrier frequency or increase the tripping level of the thermal overload relay.
Nuisance Tripping Due to a High AC Drive Carrier Frequency
Current waveforms generated by high carrier frequency drives tend to increase the temperature in overload relays. It may be
necessary to increase the trip level setting when encountering nuisance triggering of the relay.
WARNING! Fire Hazard. Confirm an actual motor overload condition is not present prior to increasing the thermal oL trip setting. Check
local electrical codes before making adjustments to motor thermal overload settings. Failure to comply could result in death or serious injury.
6.5 Installing Peripheral Devices
240 YASKAWA ELECTRIC TOEP C710636 10B Z1000U HVAC MATRIX Drive User Manual