Yaskawa Z1000 AC Drive HVAC - Manual (Page 248)

<2> Maximum Time Delay fuse is 175% of drive input current rating. This covers any Class CC, J or T class fuse.
<3> Maximum Non-time Delay fuse is 300% of drive input current rating. This covers any CC, J or T class fuse.
<4> When using semiconductor fuses, Bussman FWP are required for UL compliance.
<5> Class L fuse is also approved for this rating.
u Attachment for External Heatsink Mounting
An external attachment can be used to project the heatsink outside of an enclosure to ensure that there is sufficient air circulation
around the heatsink.
Contact a Yaskawa sales representative or Yaskawa directly for more information on this attachment.
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:
1. Low speed motor operation
2. Use of multiple motors on a single AC drive
3. Motor cable length
4. 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. Motor overheating may occur even when
the load current is within the motor rated value. 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.
UL recognized electronic thermal overload function of the drive: Speed-dependent heat characteristics are simulated using
data from standard motors and force-ventilated motors. The motor is protected from overload using this function.
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 PWM 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
248 YASKAWA ELECTRIC TOEP YAIZ1U 03A YASKAWA AC Drive – Z1000 User Manual